## 1. The Varieties of Cognitive Success



There are many different kinds of cognitive success, and they differ
from one another along various dimensions. Exactly what these various
kinds of success are, and how they differ from each other, and how
they are explanatorily related to each other, and how they can be
achieved or obstructed, are all matters of controversy. This section
provides some background to these various controversies.


### 1.1 What Kinds of Things Enjoy Cognitive Success?



Cognitive successes can differ from each other by virtue of qualifying
different kinds of things. For instance, a cognitive
success--like that of making a discovery--may be the success
of a person (e.g., Marie Curie), or of a laboratory (Los Alamos), or
of a people (the Hopi), or even, perhaps, of a psychological fragment
of a person (the unconscious). But some kinds of cognitive
success--like that of having successfully cultivated a highly
discriminating palate, say--may be the success of a person, and
perhaps even of a people, but cannot be the success of a laboratory or
of a psychological fragment. And other kinds of cognitive
success--like that of being conclusively established by all the
available evidence--may be the success of a theory, but cannot be
the success of a person--or like that of being epistemically
fruitful--may be the success of a research program, or of a
particular proof-strategy, but not of a theory. Indeed, there is a
vast range of things, spanning different metaphysical categories, that
can enjoy one or another kind of cognitive success: we can evaluate
the cognitive success of a mental state (such as that of believing a
particular proposition) or of an act (such as that of drawing a
particular conclusion), or of a procedure (such as a particular
procedure for revising degrees of confidence in response to evidence,
or a particular procedure for acquiring new evidence), or of a
relation (such as the mathematical relation between an agent's
credence function in one evidential state and her credence function in
another evidential state, or the relation of trust between one person
and another).



Some of the recent controversies concerning the objects of cognitive
success concern the metaphysical relations among the cognitive
successes of various kinds of objects: Does the cognitive success of a
process involve anything over and above the cognitive success of each
state in the succession of states that comprise the execution of that
 process?[2]
 Does the cognitive success of a particular mental state, or of a
particular mental act, depend upon its relation to the larger process
in which it
 exists?[3]
 Is the cognitive success of an organization constituted merely by the
cognitive successes of its members, or is it something over and above
those individual
 successes?[4]
 Is the cognitive success of a doxastic agent completely explicable in
terms of the successes of its doxastic states, or *vice versa*?
And either way, what sorts of doxastic states are there, and with
respect to what kinds of possible success are they assessible? The
latter dispute is especially active in recent years, with some
epistemologists regarding beliefs as metaphysically reducible to high
 credences,[5]
 while others regard credences as metaphysically reducible to beliefs
about probabilities (see Byrne in Brewer & Byrne 2005), and still
others regard beliefs and credences as related but distinct phenomena
(see Kaplan 1996, Neta 2008). 



Other recent controversies concern the issue of whether it is a
metaphysically fundamental feature of the *objects* of
cognitive success that they are, in some sense, supposed to enjoy the
kind of cognitive success in question. For instance, we might think
that what it is for some group of people to constitute a
*laboratory* is that the group is, in some sense,
*supposed* to make discoveries of a certain kind: that is the
point of bringing that group into collaboration in a particular way,
even if the individuals are spread out across different continents and
their funding sources diverse. But even if a laboratory is plausibly
characterized by a norm to which it is answerable, is something
analogous true of the other objects that can enjoy cognitive success?
Is it, for instance, a metaphysically fundamental feature of a belief
that it is, in some sense, *supposed* to be
 knowledge?[6]
 Or can belief be metaphysically characterized without appeal to this
norm? Is it, for instance, a metaphysically fundamental feature of a
person that such a creature is, in some sense, *supposed* to be
 rational?[7]
 Or can persons be metaphysically characterized without appeal to this
norm? Similar disputes arise for the other objects of cognitive
success: to what extent can we understand what these objects are
without appeal to the kinds of success that they are supposed to
enjoy?



In speaking, as we have just now, of the kinds of success that objects
are "supposed" to enjoy, we have left it open in what
sense the objects of cognitive success are "supposed" to
enjoy their success: is it that their enjoyment of that success is
good? (If so, then how is it good?) Or is it rather that their
enjoyment of that success is required? (If so, then what requires it,
and why?) We turn to that general topic next.


### 1.2 Constraints and Values



Some kinds of cognitive success involve compliance with a
*constraint*, while others involve the realization or promotion
of *values*. We can contrast these two kinds of success by
contrasting the associated kinds of failure: failure to comply with a
constraint results in *impermissibility*, whereas failure to
realize some values results in
 *sub-optimality*.[8]
 Of course, if sub-optimality is always impermissible and *vice
versa*, then the *extension* of these two categories ends
up being the same, even if the two categories are not themselves the
same. But it is implausible to regard all sub-optimality as
epistemically impermissible: cognitive success does not
*require* us to be perfectly cognitively optimal in every way.
If cognitive success is ever achievable even in principle, then at
least some degree of cognitive sub-optimality must be permissible.
Achieving greater optimality than what's required for cognitive
permissibility could then be understood as cognitive
*supererogation*. If such supererogation is possible, at least
in principle, then the permissible can fall short of the optimal.



Recent controversies concern not merely the relation between
permissibility and optimality, but also the metaphysical basis of each
kind of success. In virtue of what is some state, or act, or process,
or relation, epistemically permissible? And in virtue of what is it
optimal to whatever degree it is? Epistemic consequentialists take the
answer to the former question to be determined by appeal to the answer
to the latter. For instance, one popular form of epistemic
consequentialism claims that a particular way of forming one's
beliefs about the world is epistemically permissible just in so far as
it promotes the possession of true belief and the avoidance of false
 belief.[9]
 Another form of consequentialism, consistent with but distinct from
the first, says that a "credence function" (i.e., a
function from propositions to degrees of confidence) is optimal just
in so far as it promotes a single parameter--overall
accuracy--which is measured in such a way that, the higher
one's confidence in true propositions and the lower one's
confidence in false propositions, the greater one's overall
 accuracy.[10]
 There are also some forms of epistemic consequentialism according to
which optimality involves promotion of ends that are practical rather
than simply
 alethic.[11]
 An important controversy in the recent literature concerns the
question of whether epistemic consequentialism is true (see Berker
2013, which develops a line of argument found in Firth 1978 [1998]).
Another prominent controversy is carried on among consequentialists
themselves, and concerns the question of what values are such that
their realization or promotion constitutes optimality.



We've used the term "constraint" to denote the
bounds of what is epistemically permissible. Of course, as a matter of
deontic logic, what is permissible must include at least what is
required: for a condition to be required is simply for the complement
of that condition to not be permissible. But this leaves it open
whether, in a particular domain, what is permissible includes more
than what is required. Permissivists argue that it does (see
Schoenfield 2014 for a defense of permissivism), while
anti-permissivists argue that it does not (see White 2005 and
Schultheis 2018 for arguments against permissivism).
Anti-permissivists concerning constraints on our credences are
sometimes described as holding a "uniqueness" view, but
this label can easily mislead. A philosopher who thinks that the range
of permissible credences is no wider than the range of required
credences is an anti-permissivist--but an anti-permissivist view,
so understood, is consistent with the claim that the credences we are
required to have are not point-valued but are rather interval-valued.
Such a philosopher could, for instance, claim that there is only one
credence that you are permitted to assign to the proposition that the
cat is on the mat, and this required credence is neither .6 nor .7,
but is rather the open interval (.6, .7). 


### 1.3 Substantive and Structural



Compare the following two rules:


* (MP-Narrow) If you believe that **p* is true*, and you also
believe that *if *p* is true then *q* is true*, then you ought to
believe that **q* is true*.
* (MP-Wide) You ought not be such that you believe that **p* is
true*, and believe that *if *p* is true then *q* is true*, and
not believe that **q* is true*.



The first rule, MP-Narrow, is obviously not a rule with which we ought
to comply: if *q* is obviously false, then it's not the case that
I ought to believe that **q* is true*--not even if I believe
that *p is true*, and that *if *p* is true then *q* is
true*. Nonetheless, if *q* is obviously false, then (perhaps) I
ought not both believe that *p is true* and also believe that
*if *p* is true then *q* is true*. That's because, even if
MP-Narrow is not a rule with which we ought to comply, MP-Wide may
still be such a rule. The difference between the two rules is in the
scope of the "ought": in MP-Narrow, its scope includes
only one belief (viz., the belief that *q* is true), whereas in MP-Wide,
its scope includes a combination of two beliefs (viz., that *p* is true,
and that if *p* is true then *q* is true) and one lack of belief (viz.,
that *q* is true).



This linguistic distinction between wide scope and narrow scope
"oughts" is one expression of a general metaphysical
distinction between two kinds of cognitive success. On one side of
this distinction are those kinds of cognitive success that qualify
particular objects, e.g., a particular belief, or a particular
procedure, or a particular credence function, or a particular research
program. Examples of such success include a belief's being
justified, a procedure's being rationally required, a credence
function's being optimal. In each case, some object enjoys a
particular cognitive success, and this success obtains by virtue of
various features of that object: the features in question may be
intrinsic or relational, synchronic or diachronic, biological or
phenomenological, etc. We can call such cognitive successes
"substantive".



On the other side of this distinction are those kinds of cognitive
success that qualify the relations between various things, each of
which is itself individually assessable for cognitive success: e.g.,
the relation between a set of beliefs all held by the same agent at a
particular time, or the relation between the use of a particular
procedure, on the one hand, and one's beliefs about that
procedure, on the other, or the relation between an agent's
credence function just before receiving new evidence, and her credence
function just after receiving new evidence. Examples of this latter
kind of success include an agent's beliefs at a moment all being
consistent, or the coherence between the procedures an agent uses and
her beliefs about which procedures she ought to use. In each case, a
particular cognitive success qualifies the relations among various
objects, quite independently of whether any particular one of those
objects itself enjoys substantive cognitive success. We can call such
cognitive successes "structural". Some epistemologists
have attempted to reduce substantive successes of a particular kind to
structural
 successes.[12]
 Others have attempted to reduce structural successes of some kind to
substantive ones (see, for instance, Kiesewetter 2017, Lasonen-Aarnio
forthcoming, and Lord 2018). And still others have denied that any
such reduction is possible in either direction (see, for instance,
Worsnip 2018 and Neta 2018). In recent years, this controversy has
been most active in connection with *rational permissibility*
of beliefs, or of credences. But such a controversy could, in
principle, arise concerning any of the varieties of cognitive success
that we've distinguished so far.


### 1.4. What Explains What?



Many epistemologists attempt to explain one kind of cognitive success
in terms of other kinds. For instance, Chisholm tries to explain all
cognitive success notions in terms of just one primitive notion: that
of one attitude being *more reasonable than* another, for an
agent at a time (see Chisholm 1966). Williamson, in contrast, treats
knowledge of facts as an explanatory primitive, and suggests that
other kinds of cognitive success be explained in terms of such
knowledge (see Williamson 2002). Several prominent philosophers treat
the notion of a normative reason as primitive (see Scanlon 1998). And
so on. In each case, what is at issue is which kinds of cognitive
success are explicable in terms of which other kinds of cognitive
success. Of course, whether this issue is framed as an issue
concerning *the explication of some concepts in terms of other
concepts*, or in terms of *the grounding of some properties by
other properties*, or in some other terms still, depends on the
metaphilosophical commitments of those framing the issue. 



The issue of which *kinds* of cognitive success explain which
other kinds of cognitive success is orthogonal to the issue of which
*particular* cognitive successes explain which other particular
cognitive successes. The former issue concerns whether, for instance,
the property of knowledge is to be explained in terms of the relation
of one thing being a reason for another, or whether the relation of
being a reason for is to explained in terms of knowledge. But the
latter issue concerns whether, for instance, I am justified in holding
some particular belief--say, that the cat is on the mat--in
virtue of my knowing various specific things, e.g., that my vision is
working properly under the present circumstances, and that the object
that I am looking at now is a cat, etc. This latter issue is at the
heart of various epistemological regress puzzles, and we will return
to it below. But those regress puzzles are largely independent of the
issue of metaphysical priority being discussed here.


### 1.5 What Makes It Success?



What makes it the case that something counts as a form of cognitive
*success*? For instance, why think that *knowing the capital
of Pakistan* is a cognitive success, rather than just another
cognitive state that an agent can occupy, like *having 70%
confidence that Islamabad is the capital of Pakistan*? Not every
cognitive state enjoys cognitive success. Knowing, understanding,
mastering--these are cognitive successes. But being 70% confident
in a proposition is not, in and of itself, a cognitive success, even
if that state of confidence may be partly constitutive of an
agent's cognitive success when the agent holds it in the right
circumstances and for the right reason. What makes the difference?



Recent work on this issue tends to defend one of the following three
answers to this question: contractualism, consequentialism, or
constitutivism. The contractualist says that a particular cognitive
state counts as a kind of success because the practice of so counting
it serves certain widely held practical interests. For instance,
according to Craig (1990), we describe a person as
"knowing" something as a way of signaling that her
testimony with respect to that thing is to be trusted. The
consequentialist says that a particular cognitive state counts as a
kind of success because it tends to constitute or tends to promote
some crucial benefit. According to some consequentialists, the benefit
in question is that of having true beliefs and lacking false beliefs
(see BonJour 1985, Audi 1993). According to others, it is the benefit
of having a comprehensive understanding of reality. According to
others, it is a benefit that is not narrowly epistemic, e.g., living a
good life, or being an effective agent, or spreading one's gene
pool. Finally, the constitutivist may say that a particular cognitive
state counts as a kind of success if it is the constitutive aim of
some feature of our lives to achieve that state (see Korsgaard 2009
for a defense of constitutivism concerning norms of rationality). For
instance, the constitutivist might say that knowledge is a kind of
cognitive success by virtue of being the constitutive aim of belief,
or that understanding is a kind of cognitive success by virtue of
being the constitutive aim of reasoning, or that practical wisdom is a
kind of cognitive success by virtue of being the constitutive aim of
all human activity. Of course, there are philosophers who count as
"constitutivists" by virtue of thinking, say, that
knowledge is the constitutive aim of belief--but these same
philosophers are not thereby committed to the constitutivism described
here, since they are not committed to this explanation of what
*makes* knowledge a kind of cognitive success.



Of course, it's possible that one of the three answers mentioned
above is correct for some kinds of success, while another of the three
answers is correct for other kinds of success. Consider, for instance,
the difference between the kind of success involved in having a state
that is fitting (for instance, holding a belief
*knowledgeably*), and the kind of success involved in having a
state that is valuable (for instance, holding a belief the holding of
which is *beneficial*). Perhaps the constitutivist can explain
the former kind of success better than the consequentialist can, but
the consequentialist can explain the latter kind of success better
than the constitutivist can. Of course, if and when the demands of
these different kinds of success conflict, the agent will face the
question of how to proceed. Much recent work in epistemology has
attempted to adjudicate that question, or to interrogate the
assumption of possible conflict that gives rise to it (see, for
instance, Marusic 2015, McCormick 2015, and Rinard 2017a
and 2019b).



These different ways of understanding cognitive success each give rise
to a different understanding of the range of ways in which cognitive
success can be obstructed, and so a different understanding of the
range in which agents may be harmed, and sometimes even wronged, by
such obstructions. For instance, on the contractualist view, epistemic
harms may be built into the terms of the "contract". That
is to say, such harms may be done not merely by the specific ways in
which we interpret or implement our practice of epistemic appraisal,
but rather in the fundamental features of that practice itself. For
instance, a practice that grants the status of knowledge to a belief
formed on the basis of clearly conceptualized sense perception, but
not to a belief formed on the basis of a less clearly conceptualized
sense of a personal need, is a practice that systematically discredits
beliefs formed by exercises of empathy, relative to beliefs formed in
other ordinary
 ways.[13]


### 1.6 Epistemic Harms and Epistemic Wrongs



Obstructing an agent's cognitive success constitutes an
epistemic harm. Wrongly obstructing an agent's cognitive success
constitutes an epistemic wrong. In a situation in which false
testimony would be an epistemic harm, dishonest testimony would be an
epistemic wrong. But the range of epistemic harms and epistemic wrongs
can be much broader than those involving falsehood and deception.
Insinuation, inattention, and indoctrination can all constitute
epistemic harms or epistemic wrongs: each one can obstruct, and
sometimes wrongly obstruct, an agent's cognitive success. For
instance, I can mislead you into drawing false conclusions, even if
what I say is true: for instance, when I say "the victims were
killed by an immigrant", even if what I say is literally true,
it can mislead my hearer into thinking that the killer's being
an immigrant was in some way explanatorily relevant to her crime.
Alternatively, I can harm you, and perhaps even wrong you, by getting
you to think poorly of your own capacity to grasp a subject by not
paying attention to what you think or say. And finally, I can harm
you, and perhaps even wrong you, by indoctrinating you in a view so
strongly that you lose the ability to consider alternative views.



The epistemic harms and wrongs that we've just mentioned occur
frequently in the course of daily life, and they are typically
constituted by some particular act that we perform (e.g., lending
greater credence to the word of a man over that of a woman, or using
rhetorical devices to insinuate things that one doesn't know to
be true). But some of these harms and wrongs are constituted not by
any particular act, but rather by the procedures that give rise to
those acts: for instance, when a research program in the life sciences
implicitly assumes an ideologically-driven conception of human nature
(see Longino 1990 and Anderson 2004 for fascinating case studies). And
sometimes, the harms and wrongs might even be built into our practice
of epistemic appraisal--perhaps even a tendency that is somehow
constitutive of that very practice. Suppose, for instance, that it is
constitutive of our practice of epistemic appraisal to count someone
as knowing a fact only if they possess concepts adequate to
conceptualize that fact. Whatever may be said in favor of our
practice's having such a feature, one of its effects is clear:
those individuals who are cognitively most sensitive to facts for
which adequate conceptual resources have not yet been devised (e.g.,
someone living long before Freud who is sensitive to facts about
repression, or someone living in the nineteenth century who is
sensitive to facts about sexual harassment) will find that the
deliverances of their unique cognitive sensitivities are not counted
as knowledge. And so, these same individuals will not be granted the
same authority or credibility as other individuals, even when those
latter are less cognitively sensitive to the range of facts in
question. Recent work in feminist epistemology has helped us to gain
an appreciation of just how widespread this phenomenon is (see the
seminal discussion of epistemic injustice in M. Fricker 2007, and the
development of that account in Dotson 2014).


## 2. What is Knowledge?



Knowledge is among the many kinds of cognitive success that
epistemology is interested in understanding. Because it has attracted
vastly more attention in recent epistemology than any other variety
of cognitive success, we devote the present section to considering it
in some detail. But the English word "knowledge" lumps
together various states that are distinguished in other languages: for
instance, the verb "to know" can be translated into French
either as "*connaitre*" or as
"*savoir*", and the noun "knowledge"
can be translated into Latin as either "*cognitio*"
or as "*scientia*". Exactly how to individuate the
various kinds of cognitive success is not something that can be
determined solely by appeal to the lexicon of any particular natural
language. The present section provides a brief survey of some of the
kinds of cognitive success that are indicated by the use of
"knowledge" in English, but this is not intended to signal
that these kinds of cognitive success are all species of some common
genus. Neither, however, is it intended to signal that these kinds of
cognitive success are not all species of some common genus: at least
some philosophers have taken there to be a genus, awareness, of which
the various kinds of knowledge are all species, and with respect to
which these various kinds may all be explained (see Silva 2019 for a
defense of "awareness first" epistemology).


### 2.1 Knowing Individuals



Even if you know many facts about Napoleon, it doesn't follow
that you know Napoleon. You couldn't ever have known Napoleon,
since he died long before you were born. But, despite not having ever
known Napoleon, you could still know a great many facts about
Napoleon--perhaps you know even more facts about Napoleon than
did those who knew him most intimately. This shows that knowing a
person is not the same as knowing a great many facts about the person:
the latter is not sufficient for the former. And perhaps the former is
not even sufficient for the latter, since I might know my next door
neighbor, and yet not realize that he is an undercover agent, and that
almost everything he tells me about himself is false.



Knowing a person is a matter of being acquainted with that person, and
acquaintance involves some kind of perceptual relation to the person.
What kind of perceptual relation? Clearly, not just any perceptual
relation will do: I see and hear thousands of people while walking
around a bustling city, but it doesn't follow that I am
acquainted with any of them. Must acquaintance involve an ability to
distinguish that individual from others? It depends upon what such an
ability amounts to. I am acquainted with my next door neighbor, even
though, in some sense, I cannot distinguish him from his identical
twin: if they were together I couldn't tell who was who.



Just as we can be acquainted with a person, so too can we be
acquainted with a city, a species of bird, a planet, 1960s jazz music,
Watson and Crick's research, transphobia, and so on. If
it's not clear precisely what acquaintance demands in the case
of people, it's even less clear what it demands across all of
these various cases. If there is a genus of cognitive success
expressed by the verb "to know" with a direct object, or
by the French "connaitre", we have not yet understood that
genus.


### 2.2 Knowing How



In his groundbreaking book, *The Concept of Mind*, Gilbert Ryle
argued that knowing how to do something must be different from knowing
any set of facts. No matter how many facts you might know about
swimming, say, it doesn't follow from your knowledge of these
facts that you know how to swim. And, of course, you might know how to
swim even without knowing very many facts about swimming. For Ryle,
*knowing how* is fundamentally different from *knowing
that*.



This Rylean distinction between *knowing how* and *knowing
that* has been prominently challenged, beginning in 1975 with the
publication of Carl Ginet's *Knowledge, Perception, and
Memory*. Ginet argued that knowing how to do something was simply
knowing that a particular act was a way to do that thing. This
challenge was extended and systematized by Boer and Lycan (1975),
who argued that *knowing who*, *knowing which*,
*knowing why*, *knowing where*, *knowing when*,
and *knowing how*--all of the varieties of *knowing
wh-*, as they called it--were all just different forms of
knowing that. To know who is *F*, for instance, was simply to
*know that a particular person is *F**. To know why
*p* is simply to *know that a particular thing is the reason
why *p**. And to know how to *F* was simply to *know
that a particular act is a way to *F**. This view was
elaborated in considerable detail by Stanley and Williamson 2001, and
then challenged or refined by many subsequent writers (see, for
instance, the essays in Bengson and Moffett 2011, and also Pavese 2015
and 2017).


### 2.3 Knowing Facts



Whenever a knower (*S*) knows some fact (*p*), several
conditions must obtain. A proposition that *S* doesn't even
believe cannot be, or express, a fact that *S* knows. Therefore,
knowledge requires
 belief.[14]
 False propositions cannot be, or express, facts, and so cannot be
known. Therefore, knowledge requires truth. Finally, *S*'s
being correct in believing that *p* might merely be a matter of
luck. For example, if Hal believes he has a fatal illness, not because
he was told so by his doctor, but solely because as a hypochondriac he
can't help believing it, and it turns out that in fact he has a
fatal illness, Hal's being right about this is merely
accidental: a matter of luck (bad luck, in this
 case).[15]
 Therefore, knowledge requires a third element, one that excludes the
aforementioned luck, and so that involves *S*'s belief
being, in some sense, *justifiably* or *appropriately*
held. If we take these three conditions on knowledge to be not merely
necessary but also sufficient, then: *S* knows that *p* if
and only if *p* is true and *S* justifiably believes that
*p*. According to this account, the three conditions--truth,
belief, and justification--are individually necessary and jointly
sufficient for knowledge of
 facts.[16]



Recall that the justification condition is introduced to ensure that
*S*'s belief is not true merely because of luck. But what
must justification be, if it can ensure that? It may be thought that
*S*'s belief that *p* is true not merely because of
luck when it is reasonable or rational, from *S*'s own
point of view, to take *p* to be true. Or it may be thought that
*S*'s belief is true not merely because of luck if that
belief has a high objective probability of truth, that is, if it is
formed or sustained by reliable cognitive processes or faculties. But,
as we will see in the next section, if justification is understood in
either of these ways, it cannot ensure against luck.



It turns out, as Edmund Gettier showed, that there are cases of JTB
that are not cases of knowledge. JTB, therefore, is not
*sufficient* for knowledge. Cases like that--known as
*Gettier
 cases*[17]--arise
 because neither the possession of adequate evidence, nor origination
in reliable faculties, nor the conjunction of these conditions, is
sufficient for ensuring that a belief is not true merely because of
luck. Consider the well-known case of barn-facades: Henry drives
through a rural area in which what appear to be barns are, with the
exception of just one, mere barn facades. From the road Henry is
driving on, these facades look exactly like real barns. Henry happens
to be looking at the one and only real barn in the area and believes
that there's a barn over there. So Henry's belief is true,
and furthermore his visual experience makes it reasonable, from his
point of view, to hold that belief. Finally, his belief originates in
a reliable cognitive process: normal vision of ordinary, recognizable
objects in good lighting. Yet Henry's belief is true in this
case merely because of luck: had Henry noticed one of the barn-facades
instead, his belief would have been false. There is, therefore, broad
agreement among epistemologists that Henry's belief does not
qualify as
 knowledge.[18]




To state conditions that are jointly sufficient for knowledge, what
further element must be added to JTB? This is known as the *Gettier
problem*. Some philosophers attempt to solve the Gettier problem
by adding a fourth condition to the three conditions mentioned above,
while others attempt to solve it by either replacing or refining the
justification condition. How we understand the contrast between
replacing the justification condition and refining it depends, of
course, on how we understand the justification condition itself, which
is the topic of the next section.



Some philosophers reject the Gettier problem altogether: they reject
the aspiration to understand knowledge by trying to add to JTB. Some
such philosophers try to explain knowledge in terms of virtues: they
say that to know a fact is for the truth of one's belief to
manifest epistemic virtue (see Zagzebski 1996 and Sosa 1997). Other
such philosophers try to explain knowledge by identifying it as a
genus of many familiar species: they say that knowledge is the most
general factive mental state operator (see Williamson 2002). And still
other such philosophers try to explain knowledge by explaining its
distinctive role in some other activity. According to some, to know a
fact is for that fact to be a reason for which one can do or think
 something.[19]
 According to others, to know a fact is to be entitled to assert that
fact (see Unger 1975, Williamson 2002, DeRose 2002 for defenses of
this view; see Brown 2008b and 2010 for dissent). According to still
others, to know a fact is to be entitled to use it as a premise in
reasoning (see Hawthorne & Stanley 2008 for defense of this view;
see Neta 2009 and Brown 2008a for dissent). And according to still
others, to know a fact is to be a trustworthy informant concerning
whether that fact obtains. Finally, there are those who think that the
question "what is it to know a fact?" is misconceived: the
verb "to know" does not do the work of denoting anything,
but does a different kind of work altogether, for instance, the work
of assuring one's listeners concerning some fact or other, or
the work of indicating to one's audience that a particular
person is a trustworthy informant concerning some matter (see Lawlor
2013 for an articulation of the assurance view, and Craig 1990 for an
articulation of the trustworthy informant view).


## 3. What is Justification?



Whatever precisely is involved in knowing a fact, it is widely
recognized that *some* of our cognitive successes fall short of
knowledge: an agent may, for example, conduct herself in a way that is
intellectually unimpeachable, and yet still end up thereby believing a
false proposition. Julia has every reason to believe that her birthday
is July 15: it says so on her birth certificate and all of her medical
records, and everyone in her family insists that it is July 15.
Nonetheless, if all of this evidence is the result of some
time-keeping mistake made at the time of her birth, her belief about
her birthday could be false, despite being so thoroughly justified.
Debates concerning the nature of
 justification[20]
 can be understood as debates concerning the nature of such
non-knowledge-guaranteeing cognitive successes as the one that Julia
enjoys in this
 example.[21]


### 3.1 Deontological and Non-Deontological Justification



How is the term "justification" used in ordinary language?
Here is an example: Tom asked Martha a question, and Martha responded
with a lie. Was she justified in lying? Jane thinks she was, for
Tom's question was an inappropriate one, the answer to which was
none of Tom's business. What might Jane mean when she thinks
that Martha was justified in responding with a lie? A natural answer
is this: She means that Martha was *under no obligation* to
refrain from lying. Due to the inappropriateness of Tom's
question, it wasn't Martha's *duty* to tell the
truth. This understanding of justification, commonly labeled
*deontological*, may be defined as follows: *S* is
justified in doing *x* if and only if *S* is not obliged to
refrain from doing
 *x*.[22]



If, when we apply the word justification not to actions but to
beliefs, we mean something analogous, then the following holds:




**Deontological Justification (DJ)**
  

*S* is justified in believing that *p* if and only if
*S* is not obliged to refrain from believing that
 *p*.[23]




What kind of obligations are relevant when we wish to assess whether a
*belief*, rather than an action, is justified or unjustified?
Whereas when we evaluate an action, we are interested in assessing the
action from either a moral or a prudential point of view, when it
comes to beliefs, what matters may be something
 else,[24]
 e.g., the pursuit of *truth*, or of *understanding*, or
of *knowledge*.



Exactly what, though, must we do in the pursuit of some such
distinctively epistemic aim? According to one answer, the one favored
by evidentialists, we ought to believe in accord with our
 evidence.[25]
 For this answer to be helpful, we need an account of what our
evidence consists of, and what it means to believe in accord with it.
Other philosophers might deny this evidentialist answer, but still say
that the pursuit of the distinctively epistemic aims entails that we
ought to follow the correct epistemic norms. If this answer is going
to help us figure out what obligations the distinctively epistemic
aims impose on us, we need to be given an account of what the correct
epistemic norms
 are.][26]



The deontological understanding of the concept of justification is
common to the way philosophers such as Descartes, Locke, Moore and
Chisholm have thought about justification. Recently, however, two
chief objections have been raised against conceiving of justification
deontologically. First, it has been argued that DJ presupposes that we
can have a sufficiently high degree of control over our beliefs. But
beliefs--this objection alleges--are akin not to actions but
rather things such as digestive processes, sneezes, or involuntary
blinkings of the eye. The idea is that beliefs simply arise in or
happen to us. Therefore, beliefs are not suitable for deontological
evaluation (see Alston 1985 & 1988; also, see Chrisman 2008). To
this objection, some advocates of DJ have replied that lack of control
over our beliefs is no obstacle to thinking of justification as a
deontological status (see R. Feldman 2001a). Other advocates of DJ
have argued that we enjoy no less control over our beliefs than we do
over our intentional actions (see Ryan 2003; Sosa 2015; Steup 2000,
2008, 2012, 2017; and Rinard 2019b).



According to the second objection to DJ, deontological justification
cannot suffice for an agent to have a justified belief. This claim is
typically supported by describing cases involving either a benighted,
culturally isolated society or subjects who are cognitively deficient.
Such cases involve subjects whose cognitive limitations make it the
case that they are under no obligation to refrain from believing as
they do, but whose limitations nonetheless render them incapable of
forming justified beliefs (for a response to this objection, see Steup
1999).



Those who reject DJ think of justification not deontologically, but
rather as a property that that a belief has when it is, in some sense,
sufficiently likely to be
 true.[27]
 We may, then, define justification as follows:




**Sufficient Likelihood Justification (SLJ)**
  

*S* is justified in believing that *p* if and only if
*S* believes that *p* in a way that makes it sufficiently
likely that her belief is true.




If we wish to pin down exactly what the likelihood at issue amounts
to, we will have to deal with a variety of tricky
 issues.[28]
 For now, let us just focus on the main point. Those who prefer SLJ to
DJ would say that sufficient likelihood of truth and deontological
justification can diverge: it's possible for a belief to be
deontologically justified without being sufficiently likely to be
true. This is just what cases involving benighted cultures or
cognitively deficient subjects are designed to show (for elaboration
on the non-deontological concept of justification, see Alston
1988).


### 3.2 What Justifies Belief?



What *makes* a belief that *p* justified, when it is? Whether a
belief is justified or unjustified, there is something that
*makes* it so. Let's call the things that make a belief
justified or unjustified J-factors. Which features of a belief are
J-factors?



According to "evidentialists", it is the believer's
possession of evidence for *p*. What is it, though, to possess
evidence for *p*? Some evidentialists (though not all) would say
it is to be in an experience that presents *p* as being true.
According to these evidentialists, if the coffee in your cup tastes
sweet to you, then you have evidence that the coffee is sweet. If you
feel a throbbing pain in your head, you have evidence that you have a
headache. If you have a memory of having had cereal for breakfast,
then you have evidence about what you had for breakfast. And when you
clearly "see" or "intuit" that the proposition
"If Jack had more than four cups of coffee, then Jack had more
than three cups of coffee" is true, then you have evidence for
that proposition. On this view, evidence consists of perceptual,
introspective, memorial, and intuitional experiences, and to possess
evidence is to have an experience of that kind. So according to this
"experientialist" version of evidentialism, what makes you
justified in believing that *p* is your having an experience that
represents *p* as being true (see Conee and Feldman 2008 and
McCain 2014 for defenses of such a view). Other versions of
evidentialism might identify other factors as your evidence, but would
still insist that those factors are the J-factors.



Evidentialism is often contrasted with reliabilism, which is the view
that a belief is justified by resulting from a reliable source, where
a source is reliable just in case it tends to result in mostly true
beliefs. Reliabilists, of course, can also grant that the experiences
mentioned in the previous paragraph can matter to the justification of
your beliefs. However, they deny that justification is
*essentially* a matter of having suitable experiences. Rather,
they say, those experiences matter to the justification of your
beliefs not merely by virtue of being evidence in support of those
beliefs, but more fundamentally, by virtue of being part of the
reliable source of those beliefs. Different versions of reliabilism
have been defended: some philosophers claim that what justifies a
belief is that it is produced by a process that is reliable (for
instance, see Goldman 1986), others claim that what justifies a belief
is that it is responsive to grounds that reliably covary with the
truth of that belief, other claim that what justifies a belief is that
it is formed by the virtuous exercise of a capacity, and so on.


### 3.3 Internal vs. External



Consider a science fiction scenario concerning a human brain that is
removed from its skull, kept alive in a vat of nutrient fluid, and
electrochemically stimulated to have precisely the same total series
of experiences that you have had. Call such a brain a
"BIV": a BIV would believe everything that you believe,
and would (it is often thought) be justified in believing those things
to precisely the same extent that you are justified in believing them.
Therefore, justification is determined solely by those internal
factors that you and your envatted brain doppelganger share. This view
is what has come to be called "internalism" about
 justification.[29]



Externalism is simply the denial of internalism. Externalists say that
what we want from justification is the kind of likelihood of truth
needed for knowledge, and the internal conditions that you share with
your BIV doppelganger do not generate such likelihood of truth. So
justification involves external
 conditions.[30]



Among those who think that justification is internal, there is no
unanimity on how to understand the notion of internality--i.e.,
what it is about the factors that you share with your BIV doppelganger
that makes those factors relevant to justification. We can distinguish
between two approaches. According to the first, justification is
internal because we enjoy a special kind of access to J-factors: they
are *always* recognizable on
 reflection.[31]
 Hence, assuming certain further premises (which will be mentioned
momentarily), justification itself is always recognizable on
 reflection.[32]
 According to the second approach, justification is internal because
J-factors are always mental states (see Conee and Feldman 2001).
Let's call the former *accessibility internalism* and the
latter *mentalist internalism*.



Evidentialism is typically associated with internalism of at least one
of these two varieties, and reliabilism with
 externalism.[33]
 Let us see why. Evidentialism says, at a minimum, two things:


* E1 What makes
one justified in believing *p* is nothing over and above the
evidence that one possesses.
* E2 What
evidence one possesses is fixed by one's mental
states.



By virtue of E2, evidentialism is an instance of mentalist
internalism. Whether evidentialism is also an instance of
accessibility internalism is a more complicated issue. The conjunction
of E1 and E2 by itself implies nothing about the accessibility of
justification. But mentalist internalists who endorse the first
principle below will also be committed to accessibility internalism,
and evidentialists who also endorse the second principle below will be
committed to the accessibility of justification:




**Luminosity**
  

One's own mind is cognitively luminous: Whenever one is in a
particular mental state, one can always recognize on reflection what
mental states one is in, and in particular, one can always recognize
on reflection what evidence one
 possesses.[34]



**Necessity**
  

*The principles that determine what* is evidence for what are
*a priori*
 recognizable.[35]
 Relying on *a priori* insight, one can therefore always
recognize on reflection whether, or the extent, to which a particular
body of evidence is evidence for
 *p*.[36]




Although E1 and E2 by themselves do not imply access internalism,
their conjunction with Luminosity and Necessity may imply access
 internalism.[37]



Next, let us consider why reliabilism is an externalist theory.
Reliabilism says that the justification of one's beliefs is a
function of the reliability of one's belief sources such as
memorial, perceptual and introspective states and processes. Even if
the operations of the sources are mental states, their reliability is
not itself be a mental state. Therefore, reliabilists reject mentalist
internalism. Moreover, insofar as the reliability of one's
belief sources is not itself recognizable by means of reflection, how
could reflection enable us to recognize when such justification
 obtains?[38]
 Reliabilists who take there to be no good answer to this question
also reject access
 internalism.[39]


## 4. The Structure of Knowledge and Justification



Anyone who knows anything necessarily knows many things. Our knowledge
forms a body, and that body has a structure: knowing some things
requires knowing other things. But what is this structure?
Epistemologists who think that knowledge involves justification tend
to regard the structure of our knowledge as deriving from the
structure of our justifications. We will, therefore, focus on the
latter.


### 4.1 Foundationalism



According to foundationalism, our justified beliefs are structured
like a building: they are divided into a foundation and a
superstructure, the latter resting upon the former. Beliefs belonging
to the foundation are *basic*. Beliefs belonging to the
superstructure are *nonbasic* and receive justification from
the justified beliefs in the
 foundation.[40]



Before we evaluate this foundationalist account of justification, let
us first try to spell it out more precisely. What is it for a
justified belief to be basic? According to one approach, what makes a
justified belief basic is that it doesn't receive its
justification from any other beliefs. The following definition
captures this thought:




**Doxastic Basicality (DB)**
  

*S*'s justified belief that *p* is basic if and only
if *S*'s belief that *p* is justified without owing
its justification to any of *S*'s other beliefs.




Let's consider what would, according to DB, qualify as an
example of a basic belief. Suppose you notice (for whatever reason)
someone's hat, and you also notice that that hat looks blue to
you. So you believe


* (B) It appears
to me that that hat is blue.



Unless something very strange is going on, (B) is an example of a
justified belief. DB tells us that (B) is basic if and only if it does
not owe its justification to any other beliefs of yours. So if (B) is
indeed basic, there might be some item or other to which (B) owes its
justification, but that item would not be another belief of yours. We
call this kind of basicality "doxastic" because it makes
basicality a function of how your doxastic system (your belief system)
is structured.



Let us turn to the question of where the justification that attaches
to (B) might come from, if we think of basicality as defined by DB.
Note that DB merely tells us how (B) is *not* justified. It
says nothing about *how* (B) is justified. DB, therefore, does
not answer that question. What we need, in addition to DB, is an
account of *what it is* that justifies a belief such as (B).
According to one strand of foundationalist thought, (B) is justified
because it can't be false, doubted, or corrected by others. On
such a view, (B) is justified because (B) carries with it an
*epistemic privilege* such as infallibility, indubitability, or
incorrigibility (for a discussion of various kinds of epistemic
privilege, see Alston 1971 [1989]).



Note that (B) is a belief about how the hat *appears* to you.
So (B) is a belief about a perceptual experience of yours. According
to the version of foundationalism just considered, a subject's
basic beliefs are introspective beliefs about the subject's own
mental states, of which perceptual experiences make up one subset.
Other mental states about which a subject can have basic beliefs may
include such things as having a headache, being tired, feeling
pleasure, or having a desire for a cup of coffee. Beliefs about
external objects cannot qualify as basic, according to this kind of
foundationalism, for it is impossible for such beliefs to enjoy the
kind of epistemic privilege necessary for being basic.



According to a different version of foundationalism, (B) is justified
by some further mental state of yours, but not by a further
*belief* of yours. Rather, (B) is justified by the very
*perceptual experience* that (B) itself is about: the
hat's looking blue to you. Let "(E)" represent that
experience. According to this alternative proposal, (B) and (E) are
distinct mental states. The idea is that what justifies (B) is (E).
Since (E) is an experience, not a belief of yours, (B) can, according
to DB, still be basic.



Let's call the two versions of foundationalism we have
distinguished *privilege foundationalism* and *experiential
foundationalism*. Privilege foundationalism is generally thought
to restrict basic beliefs so that beliefs about contingent,
mind-independent facts cannot be basic, since beliefs about such facts
are generally thought to lack the privilege that attends our
introspective beliefs about our own present mental states, or our
beliefs about *a priori* necessities. Experiential
foundationalism is not restrictive in the same way. Suppose instead of
(B), you believe


* (H) That hat
is blue.



Unlike (B), (H) is about the hat itself, and not the way the hat
appears to you. Such a belief is not one about which we are infallible
or otherwise epistemically privileged. Privilege foundationalism
would, therefore, classify (H) as nonbasic. It is, however, quite
plausible to think that (E) justifies not only (B) but (H) as well. If
(E) is indeed what justifies (H), and (H) does not receive any
additional justification from any further beliefs of yours, then (H)
qualifies, according to DB, as basic.



Experiential Foundationalism, then, combines two crucial ideas: (i)
when a justified belief is basic, its justification is not owed to any
other belief; (ii) what in fact justifies basic beliefs are
experiences.



Under ordinary circumstances, perceptual beliefs such as (H) are not
based on any *further beliefs* about one's own perceptual
experiences. It is not clear, therefore, how privilege foundationalism
can account for the justification of ordinary perceptual beliefs like
 (H).[41]
 Experiential foundationalism, on the other hand, has no trouble at
all explaining how ordinary perceptual beliefs are justified: they are
justified by the perceptual experiences that give rise to them. This
could be viewed as a reason for preferring experiential
foundationalism to privilege foundationalism.



DB articulates one conception of basicality. Here's an
alternative conception:




**Epistemic Basicality (EB)**
  

*S*'s justified belief that *p* is basic if and only
if *S*'s justification for believing that *p* does not
depend on any justification *S* possesses for believing a further
proposition,
 *q*.[42]




EB makes it more difficult for a belief to be basic than DB does. To
see why, we turn to the chief question (let's call it the
"J-question") that advocates of experiential
foundationalism face:




**The J-Question**
  

Why are perceptual experiences a source of justification?




One way of answering the J-question is as follows: perceptual
experiences are a source of justification only when, and only because,
we have justification for taking them to be
 reliable.[43]
 Note that your having justification for believing that *p*
doesn't entail that you actually believe *p*. Thus, your
having justification for attributing reliability to your perceptual
experiences doesn't entail that you actually believe them to be
reliable.



What might give us justification for thinking that our perceptual
experiences are reliable? That's a complicated issue. For our
present purposes, let's consider the following answer: We
remember that they have served us well in the past. We are supposing,
then, that justification for attributing reliability to your
perceptual experiences consists of memories of perceptual success. On
this view, a perceptual experience (E) justifies a perceptual belief
only when, and only because, you have suitable track-record memories
that give you justification for considering (E) reliable. (Of course,
this raises the question why those memories give us justification, but
there are many different approaches to this question, as we'll
see more fully below.)



If this view is correct, then it is clear how DB and EB differ. Your
having justification for (H) depends on your having justification for
believing something else in addition to (H), namely that your visual
experiences are reliable. As a result (H) is not basic in the sense
defined by EB. However, (H) might still be basic in the sense defined
by DB. If you are justified in believing (H) and your justification is
owed solely to (E) and (M), neither of which includes any beliefs,
then your belief is doxastically--though not
epistemically--basic. 



We've considered one possible answer to the J-question, and
considered how EB and DB differ if that answer is correct. But there
are other possible answers to the J-question. Another answer is that
perceptual experiences are a source of justification when, and
because, they are of types that reliably produce true
 beliefs.[44]
 Another answer is that perceptual experiences are a source of
justification when, and because, they are of types that reliably
indicate the truth of their content. Yet another answer is that
perceptual experiences are a source of justification when, and
because, they have a certain phenomenology: that of presenting their
content as
 true.[45]



To conclude this section, let us briefly consider how justification is
supposed to be transferred from basic to nonbasic beliefs. There are
two options: the justificatory relation between basic and nonbasic
beliefs could be deductive or non-deductive. If we take the relation
to be deductive, each of one's nonbasic beliefs would have to be
such that it can be deduced from one's basic beliefs. But if we
consider a random selection of typical beliefs we hold, it is not easy
to see from which basic beliefs they could be deduced.
Foundationalists, therefore, typically conceive of the link between
the foundation and the superstructure in non-deductive terms. They
would say that, for a given set of basic beliefs, B, to justify a
nonbasic belief, B\*, it isn't necessary that B entails B\*.
Rather, it is sufficient that, the inference from B to B\* is a
rational one--however such rationality is to be
 understood.[46]


### 4.2 Coherentism



Foundationalism says that knowledge and justification are structured
like a building, consisting of a superstructure that rests upon a
foundation. According to coherentism, this metaphor gets things wrong.
Knowledge and justification are structured like a *web* where
the strength of any given area depends on the strength of the
surrounding areas. Coherentists, then, deny that there are any basic
beliefs. As we saw in the previous section, there are two different
ways of conceiving of basicality. Consequently, there are two
corresponding ways of construing coherentism: as the denial of
doxastic basicality or as the denial of epistemic basicality. Consider
first coherentism as the denial of doxastic basicality:




**Doxastic Coherentism**
  

Every justified belief receives its justification from other beliefs
in its epistemic neighborhood.




Let us apply this thought to the hat example we considered in
 Section 3.1.
 Suppose again you notice someone's hat and believe


* (H) That hat is
blue.



Let's agree that (H) is justified. According to coherentism, (H)
receives its justification from other beliefs in the epistemic
vicinity of (H). They constitute your evidence or your reasons for
taking (H) to be true. Which beliefs might make up this set of
justification-conferring neighborhood beliefs?



We will consider two approaches to answering this question. The first
is known as *inference to the best explanation*. Such
inferences generate what is called *explanatory coherence* (see
chapter 7 in Harman 1986). According to this approach, we must suppose
you form a belief about the way the hat appears to you in your
perceptual experiences, and a second belief to the effect that your
perceptual experience, the hat's looking blue to you, is best
explained by the hypothesis that (H) is true. So the relevant set of
beliefs is the following:


* (1) I am
having a visual experience (E): the hat looks blue to me.
* (2) My having
(E) is best explained by assuming that (H) is true.



There are of course alternative explanations of why you have (E).
Perhaps you are hallucinating that the hat is blue. Perhaps an evil
demon makes the hat look blue to you when in fact it is red. Perhaps
you are the sort of person to whom hats always look blue. An
explanatory coherentist would say that, compared with these, the
hat's actual blueness is a superior explanation. That's
why you are justified in believing (H). Note that an explanatory
coherentist can also explain the *lack* of justification.
Suppose you remember that you just took a hallucinatory drug that
makes things look blue to you. That would prevent you from being
justified in believing (H). The explanatory coherentist can account
for this by pointing out that, in the case we are considering now, the
truth of (H) would not be the *best* explanation of why you are
having experience (E). Rather, your having taken the hallucinatory
drug would explain your having (E) at least as well as the hypothesis
(H) would explain it. That's why, according to the explanatory
coherentist, in this variation of our original case you are not
justified in believing (H).



One challenge for explanatory coherentists is to explain what makes
one explanation better than another. Let's use the evil demon
hypothesis to illustrate this challenge. What we need is an
explanation of why you are having (E). According to the evil demon
hypothesis, you are having (E) because the evil demon is causing you
to have (E), in order to trick you. The explanatory coherentist would
say that, if the bulk of our beliefs about the mind-independent world
are justified, then this "evil demon" hypothesis is a bad
explanation of why you are having (E). But why is it bad? What we need
to answer this question is a general and principled account of what
makes one explanation better than another. Suppose we appeal to the
fact that you are not *justified* in believing in the existence
of evil demons. The general idea would be this: If there are two
competing explanations, E1 and E2, and E1 consists of or includes a
proposition that you are not justified in believing whereas E2 does
not, then E2 is better than E1. The problem with this idea is that it
puts the cart before the horse. Explanatory coherentism is supposed to
help us understand what it is for beliefs to be justified. It
doesn't do that if it accounts for the difference between better
and worse explanations by making use of the difference between
justified and unjustified belief. If explanatory coherentism were to
proceed in this way, it would be a circular, and thus uninformative,
account of justification. So the challenge that explanatory
coherentism must meet is to give an account, without using the concept
of justification, of what makes one explanation better than
another.



Let us move on to the second way in which the coherentist approach
might be carried out. Recall what a subject's justification for
believing *p* is all about: possessing a link between the belief
that *p* and *p*'s truth. Suppose the subject knows
that the origin of her belief that *p* is reliable. So she knows
that beliefs coming from this source tend to be true. Such knowledge
would give her an excellent link between the belief and its truth. So
we might say that the neighborhood beliefs which confer justification
on (H) are the following:


* (1) I am having a
visual experience (E): the hat looks blue to me.
* (3)Experiences
like (E) are reliable.



Call coherentism of this kind *reliability coherentism*. If you
believe (1) and (3), you are in possession of a good reason for
thinking that the hat is indeed blue. So you are in possession of a
good reason for thinking that the belief in question, (H), is true.
That's why, according to reliability coherentism, you are
justified in believing (H).



Like explanatory coherentism, this view faces a circularity problem.
If (H) receives its justification in part because you also believe
(3), (3) itself must be justified. But where would your justification
for (3) come from? One answer would be: from your memory of perceptual
success in the past. You remember that your visual experiences have
had a good track record. They have rarely led you astray. The problem
is that you can't justifiably attribute a good track record to
your perceptual faculties without using your perceptual faculties. So
if reliability coherentism is going to work, it would have to be
legitimate to use a faculty for the very purpose of establishing the
reliability of that faculty itself. But it is not clear that this is
 legitimate.[47]



We have seen that explanatory coherentism and reliability coherentism
each face its own distinctive circularity problem. Since both are
versions of *doxastic* coherentism, they both face a further
difficulty: Do people, under normal circumstances, really form beliefs
like (1), (2), and (3)? It would seem they do not. It could be
objected, therefore, that these two versions of coherentism make
excessive intellectual demands of ordinary subjects who are unlikely
to have the background beliefs that, according to these versions of
coherentism, are needed for justification. This objection could be
avoided by stripping coherentism of its doxastic element. The result
would be the following version of coherentism, which results from
rejecting EB (the epistemic conception of basicality):




**Dependence Coherentism**
  

Whenever one is justified in believing a proposition
*p*1, one's justification for believing
*p*1 depends on justification one has for believing
some further propositions, *p*1, *p*2,
... *pn*.




An explanatory coherentist might say that, for you to be justified in
believing (H), it's not necessary that you actually
*believe*
(1)
 and
 (2).
 However, it is necessary that you have *justification* for
believing (1) and (2). It is your having justification for (1) and (2)
that gives you justification for believing (H). A reliability
coherentist might make an analogous point. She might say that, to be
justified in believing (H), you need not believe anything about the
reliability of your belief's origin. You must, however, have
justification for believing that your belief's origin is
reliable; that is, you must have justification for (1) and
 (3).
 Both versions of dependence coherentism, then, rest on the
supposition that it is possible to have justification for a
proposition without actually believing that proposition.



Dependence coherentism is a significant departure from the way
coherentism has typically been construed by its advocates. According
to the typical construal of coherentism, a belief is justified, only
if the subject has certain further *beliefs* that constitute
reasons for the given belief. Dependence coherentism rejects this.
According to it, justification need not come in the form of beliefs.
It can come in the form of introspective and memorial experience, so
long as such experience gives a subject justification for beliefs
about either reliability or explanatory coherence. In fact, dependence
coherentism allows for the possibility that a belief is justified, not
by receiving *any* of its justification from other beliefs, but
solely by suitable perceptual experiences and memory
 experience.[48]



Next, let us examine some of the reasons provided in the debate over
foundationalism and coherentism.


### 4.3 Why Foundationalism?



The main argument for foundationalism is called the *regress
argument*. It's an argument from elimination. With regard to
every justified belief, B1, the question arises of where
B1's justification comes from. If B1 is
not basic, it would have to come from another belief, B2.
But B2 can justify B1 only if B2 is
justified itself. If B2 is basic, the justificatory chain
would end with B2. But if B2 is not basic, we
need a further belief, B3. If B3 is not basic,
we need a fourth belief, and so forth. Unless the ensuing regress
terminates in a basic belief, we get two possibilities: the regress
will either *loop back* to B1 or continue *ad
infinitum*. According to the regress argument, both of these
possibilities are unacceptable. Therefore, if there are justified
beliefs, there must be basic
 beliefs.[49]



This argument suffers from various weaknesses. First, we may wonder
whether the alternatives to foundationalism are really unacceptable.
In the recent literature on this subject, we actually find an
elaborate defense of the position that infinitism is the correct
solution to the regress
 problem.[50]
 Nor should circularity be dismissed too quickly. The issue is not
whether a simple argument of the form **p* therefore *p** can
justify the belief that *p*. Of course it cannot. Rather, the
issue is ultimately whether, in the attempt to show that trust in our
faculties is reasonable, we may make use of the input our faculties
deliver. Whether such circularity is as unacceptable as a
**p*-therefore-*p** inference is an open question. Moreover, the
avoidance of circularity does not come cheap. Experiential
foundationalists claim that perception is a source of justification.
Hence they need to answer the J-question: *Why* is perception a
source of justification? As we saw above, if we wish to answer this
question without committing ourselves to the kind of circularity
dependence coherentism involves, we must choose between externalism
and an appeal to brute necessity.



The second weakness of the regress argument is that its conclusion
merely says this: If there are justified beliefs, there must be
justified beliefs that do not receive their justification from other
beliefs. Its conclusion does not say that, if there are justified
beliefs, there must be beliefs whose justification is independent of
any justification for further beliefs. So the regress argument, if it
were sound, would merely show that there must be *doxastic*
basicality. Dependence coherentism, however, allows for doxastic
basicality. So the regress argument merely defends experiential
foundationalism against doxastic coherentism. It does not tell us why
we should prefer experiential foundationalism to dependence
coherentism.



Experiential foundationalism can be supported by citing cases like the
blue hat example. Such examples make it plausible to assume that
perceptual experiences are a source of justification. But they do not
arbitrate between dependence coherentism and experiential
foundationalism, since both of those views appeal to perceptual
experiences to explain why perceptual beliefs are justified.



Finally, foundationalism can be supported by advancing objections to
coherentism. One prominent objection is that coherentism somehow fails
to ensure that a justified belief system is in contact with reality.
This objection derives its force from the fact that fiction can be
perfectly coherent. Why think, therefore, that a belief system's
coherence is a reason for thinking that the beliefs in that system
tend to be true? Coherentists could respond to this objection by
saying that, if a belief system contains beliefs such as "Many
of my beliefs have their origin in perceptual experiences" and
"My perceptual experiences are reliable", it is reasonable
for the subject to think that her belief system brings her into
contact with external reality. This looks like an effective response
to the no-contact-with-reality objection. Moreover, it is not easy to
see why foundationalism itself should be better positioned than
coherentism when contact with reality is the issue. What is meant by
"ensuring" contact with reality? If foundationalists
expect a *logical guarantee* of such contact, basic beliefs
must be infallible. That would make contact with reality a rather
expensive commodity. Given its price, foundationalists might want to
lower their expectations. According to an alternative construal, we
expect merely the *likelihood* of contact with reality. But if
coherentists account for the epistemic value of perception in any way,
then they can meet that expectation as well as foundationalists
can.



Since coherentism can be construed in different ways, it is unlikely
that there is one single objection that succeeds in refuting all
possible versions of coherentism. Doxastic coherentism, however, seems
particularly vulnerable to criticism coming from the foundationalist
camp. One of these we considered already: It would seem that doxastic
coherentism makes excessive intellectual demands on believers. When
dealing with the mundane tasks of everyday life, we don't
normally bother to form beliefs about the explanatory coherence of our
beliefs or the reliability of our belief sources. According to a
second objection, doxastic coherentism fails by being insensitive to
the epistemic relevance of perceptual experiences. Foundationalists
could argue as follows. Suppose Kim is observing a chameleon that
rapidly changes its colors. A moment ago it was blue, now it's
purple. Kim still believes it's blue. Her belief is now
unjustified because she believes the chameleon is blue even though it
*looks* purple to her. Then the chameleon changes its color
back to blue. Now Kim's belief that the chameleon is blue is
justified again because the chameleon once again *looks* blue
to her. The point would be that what's responsible for the
changing justificatory status of Kim's belief is solely the way
the chameleon looks to her. Since doxastic coherentism does not
attribute epistemic relevance to perceptual experiences by themselves,
it cannot explain why Kim's belief is first justified, then
unjustified, and eventually justified
 again.[51]


### 4.4 Why Coherentism?



Coherentism is typically defended by attacking foundationalism as a
viable alternative. To argue against privilege foundationalism,
coherentists pick an epistemic privilege they think is essential to
foundationalism, and then argue that either no beliefs, or too few
beliefs, enjoy such a privilege. Against experiential foundationalism,
different objections have been advanced. One line of criticism is that
perceptual experiences don't have propositional content.
Therefore, the relation between a perceptual belief and the perceptual
experience that gives rise to it can only be causal. But it is not
clear that this is correct. When you see the hat and it looks blue to
you, doesn't your visual experience--its looking blue to
you--have the propositional content *that the hat is
blue*? If it does, then why not allow that your perceptual
experience can play a justificatory
 role?[52]



Another line of thought is that, if perceptual experiences have
propositional content, they cannot stop the justificatory regress
because they would then be in need of justification themselves. That,
however, is a strange thought. In our actual epistemic practice, we
never demand of others to justify the way things appear to them in
their perceptual experiences. Indeed, such a demand would seem absurd.
Suppose I ask you: "Why do you think that the hat is
blue?" You answer: "Because it looks blue to me".
There are sensible further questions I might ask at that point. For
instance, I might ask: "Why do you think its looking blue to you
gives you a reason for believing it is blue?" Or I might ask:
"Couldn't you be mistaken in believing it looks blue to
you?" But now suppose I ask you: "Why do you suppose the
perceptual experience in which the hat looks blue to you is
justified?" In response to that question, you should accuse me
of misusing the word "justification". I might as well ask
you what it is that justifies your headache when you have one, or what
justifies the itch in your nose when you have one. The latter
questions, you should reply, would be as absurd as my request for
stating a justifying reason for your perceptual
 experience.[53]



Experiential foundationalism, then, is not easily dislodged. On what
grounds could coherentists object to it? To raise problems for
experiential foundationalism, coherentists could press the J-question:
Why are perceptual experiences a source of justification? If
foundationalists answer the J-question appealing to evidence that
warrants the attribution of reliability to perceptual experiences,
experiential foundationalism morphs into dependence coherentism. To
avoid this outcome, foundationalists would have to give an alternative
answer. One way of doing this would be to adopt the epistemic
conception of basicality, and view it as a matter of brute necessity
that perception is a source of justification. It remains to be seen
whether such a view is sustainable.


## 5. Sources of Knowledge and Justification



Beliefs arise in people for a wide variety of causes. Among them, we
must list psychological factors such as desires, emotional needs,
prejudice, and biases of various kinds. Obviously, when beliefs
originate in sources like these, they don't qualify as knowledge
even if true. For true beliefs to count as knowledge, it is necessary
that they originate in sources we have good reason to consider
reliable. These are perception, introspection, memory, reason, and
testimony. Let us briefly consider each of these.


### 5.1 Perception



Our perceptual faculties include at least our five senses: sight,
touch, hearing, smelling, and tasting. We must distinguish between an
experience that can be classified as *perceiving* that *p*
(for example, seeing that there is coffee in the cup and tasting that
it is sweet), which entails that *p* is true, and a perceptual
experience in which it seems to us as though *p*, but where
*p* might be false. Let us refer to this latter kind of
experience as *perceptual seemings*. The reason for making this
distinction lies in the fact that perceptual experience is fallible.
The world is not always as it appears to us in our perceptual
experiences. We need, therefore, a way of referring to perceptual
experiences in which *p* seems to be the case that allows for the
possibility of *p* being false. That's the role assigned to
perceptual seemings. So some perceptual seemings that *p* are
cases of perceiving that *p*, others are not. When it looks to
you as though there is a cup of coffee on the table and in fact there
is, the two states coincide. If, however, you hallucinate that there
is a cup on the table, you have a perceptual seeming that *p*
without perceiving that *p*.



One family of epistemological issues about perception arises when we
concern ourselves with the psychological nature of the perceptual
processes through which we acquire knowledge of external objects.
According to *direct realism*, we can acquire such knowledge
because we can directly perceive such objects. For example, when you
see a tomato on the table, *what you perceive* is the tomato
itself. According to *indirect realism*, we acquire knowledge
of external objects by virtue of perceiving something else, namely
appearances or sense-data. An indirect realist would say that, when
you see and thus know that there is a tomato on the table, what you
really see is not the tomato itself but a tomato-like sense-datum or
some such entity.



Direct and indirect realists hold different views about the structure
of perceptual knowledge. Indirect realists would say that we acquire
perceptual knowledge of external objects by virtue of perceiving sense
data that represent external objects. Sense data enjoy a special
status: we know directly what they are like. So indirect realists
think that, when perceptual knowledge is foundational, it is knowledge
of sense data and other mental states. Knowledge of external objects
is indirect: derived from our knowledge of sense data. The basic idea
is that we have indirect knowledge of the external world because we
can have foundational knowledge of our own mind. Direct realists, in
contrast, say that perceptual experiences can give you direct,
foundational knowledge of external
 objects.[54]



We take our perceptual faculties to be reliable. But how can we know
that they are reliable? For externalists, this might not be much of a
challenge. If the use of reliable faculties is sufficient for
knowledge, and if by using reliable faculties we acquire the belief
that our faculties are reliable, then we come to know that our
faculties are reliable. But even externalists might wonder how they
can, via argument, *show* that our perceptual faculties are
reliable. The problem is this. It would seem the only way of acquiring
knowledge about the reliability of our perceptual faculties is through
memory, through remembering whether they served us well in the past.
But should I trust my memory, and should I think that the episodes of
perceptual success that I seem to recall were in fact episodes of
perceptual success? If I am entitled to answer these questions with
"yes", then I need to have, to begin with, reason to view
my memory and my perceptual experiences as reliable. It would seem,
therefore, that there is no non-circular way of arguing for the
reliability of one's perceptual
 faculties.[55]


### 5.2 Introspection



Introspection is the capacity to inspect the present contents of
one's own mind. Through introspection, one knows what mental
states one is currently in: whether one is thirsty, tired, excited, or
depressed. Compared with perception, introspection appears to have a
special status. It is easy to see how a perceptual seeming can go
wrong: what looks like a cup of coffee on the table might be just be a
clever hologram that's visually indistinguishable from an actual
cup of coffee. But can it introspectively seem to me that I have a
headache when in fact I do not? It is not easy to see how it could be.
Thus introspection is widely thought to enjoy a special kind of
immunity to error. But what does this amount to?



First, it could be argued that, when it comes to introspection, there
is no difference between appearance and reality; therefore,
introspective seemings infallibly constitute their own success.
Alternatively, one could view introspection as a source of certainty.
Here the idea is that an introspective experience of *p*
eliminates any possible reason for doubt as to whether *p* is
true. Finally, one could attempt to explain the specialness of
introspection by examining the way we respond to first-person reports:
typically, we attribute a special authority to such reports. According
to this approach, introspection is incorrigible: its deliverances
cannot be corrected by any other source.



However we construe the special kind of immunity to error that
introspection enjoys, such immunity is not enjoyed by perception. Some
foundationalists have therefore thought that the foundations of our
empirical knowledge can be furnished by introspection of our own
perceptual experiences, rather than perception of mind-independent
things around us.



Is it really true, however, that, compared with perception,
introspection is in some way special? Critics of foundationalism have
argued that introspection is not infallible. Might one not confuse an
unpleasant itch for a pain? Might I not think that the shape before me
appears circular to me when in fact it appears slightly elliptical to
me? If it is indeed possible for introspection to mislead, then it is
not clear in what sense introspection can constitute its own success,
provide certainty, or even incorrigibility. Yet it also isn't
easy to see either how, if one clearly and distinctly feels a
throbbing headache, one could be mistaken about that. Introspection,
then, turns out to be a mysterious faculty. On the one hand, it does
not seem to be an infallible faculty; on the other hand, it is not
easy to see how error is possible in many specific cases of
 introspection.[56]



The definition of introspection as the capacity to know the present
contents of one's own mind leaves open the question of how
similar the different exercises of this capacity may be from one
another. According to some epistemologists, when we exercise this
capacity with respect to our sensations, we are doing something very
different from what we do when we exercise this capacity with respect
to our own conscious beliefs, intentions, or other rationally
evaluable states of mind: our exercises of this capacity with respect
to our own conscious, rationally evaluable states of mind is, they
claim, partly *constitutive* of our being in those very states.
In support of this claim, they point out that we sometimes address
questions of the form "do you believe that *p*?" by
considering whether it is true that *p*, and reporting our belief
concerning *p* not by inspecting our mind, but rather by making up our
mind (see Moran 2001 and Boyle 2009 for defenses of this view; see
Gertler 2011 for objections to the view).


### 5.3 Memory



Memory is the capacity to retain knowledge acquired in the past. What
one remembers, though, need not be a past event. It may be a present
fact, such as one's telephone number, or a future event, such as
the date of the next elections. Memory is, of course, fallible. Not
every experience as of remembering that *p* is an instance of
correctly remembering that *p*. We should distinguish, therefore,
between remembering that *p* (which entails the truth of
*p*) and *seeming* to remember that *p* (which does
not entail the truth of *p*).



What makes memorial seemings a source of justification? Is it a
necessary truth that, if one has a memorial seeming that *p*, one
has thereby prima facie justification for *p*? Or is memory a
source of justification only if, as coherentists might say, one has
reason to think that one's memory is reliable? Or is memory a
source of justification only if, as externalists would say, it is in
fact reliable? Also, how can we respond to skepticism about knowledge
of the past? Memorial seemings of the past do not guarantee that the
past is what we take it to be. We think that we are older than five
minutes, but it is logically possible that the world sprang into
existence just five minutes ago, complete with our dispositions to
have memorial seemings of a more distant past and items such as
apparent fossils that suggest a past going back millions of years. Our
seeming to remember that the world is older than a mere five minutes
does not entail, therefore, that it really is. Why, then, should we
think that memory is a source of knowledge about the
 past?[57]


### 5.4 Reason



Some beliefs are (thought to be) justified independently of
experience. Justification of that kind is said to be *a
priori*. A standard way of defining *a priori*
justification is as follows:




***A Priori* Justification**
  

*S* is justified *a priori* in believing that *p* if
and only if *S*'s justification for believing that *p*
does not depend on any experience.




When they are knowledgeably held, beliefs justified in this way are
instances of *a priori*
 knowledge.[58]



What exactly counts as experience? If by "experience" we
mean just *perceptual* experiences, justification deriving from
introspective or memorial experiences would count as *a
priori*. For example, I could then know *a priori* that
I'm thirsty, or what I ate for breakfast this morning. While the
term "*a priori*" is sometimes used in this way,
the strict use of the term restricts *a priori* justification
to justification derived *solely* from the use of reason.
According to this usage, the word "experiences" in the
definition above includes perceptual, introspective, and memorial
experiences alike. On this narrower understanding, paragons of what I
can know *a priori* are conceptual truths (such as "All
bachelors are unmarried"), and truths of mathematics, geometry
and logic.



Justification and knowledge that is not *a priori* is called
"*a posteriori*" or "empirical". For
example, in the narrow sense of "*a priori*",
whether I'm thirsty or not is something I know empirically (on
the basis of introspective experiences), whereas I know *a
priori* that 12 divided by 3 is 4.



Several important issues arise about *a priori* knowledge.
First, does it exist at all? Skeptics about apriority deny its
existence. They don't mean to say that we have no knowledge of
mathematics, geometry, logic, and conceptual truths. Rather, what they
claim is that all such knowledge is
 empirical.[59]



Second, if *a priori* justification is possible, exactly what
does it involve? What *makes* a belief such as "All
bachelors are unmarried" justified? Is it an unmediated grasp of
the truth of this proposition? Or does it consist of grasping that the
proposition is *necessarily* true? Or is it the purely
intellectual state of "seeing" (with the "eye of
reason") or "intuiting" that this proposition is
true (or necessarily true)? (see Bengson 2015 and Chudnoff 2013 for
sophisticated defenses of this view). Or is it, as externalists would
suggest, the reliability of the cognitive process by which we come to
recognize the truth of such a proposition?



Third, if *a priori* knowledge exists, what is its extent?
*Empiricists* have argued that *a priori* knowledge is
limited to the realm of the *analytic*, consisting of
propositions true solely by virtue of our concepts, and so do not
convey any information about the world. Propositions that convey
genuine information about world are called *synthetic*. *a
priori* knowledge of synthetic propositions, empiricists would
say, is not possible. *Rationalists* deny this. They might
appeal to a proposition such as "If a ball is green all over,
then it doesn't have black spots" as an example of a
proposition that is both synthetic and yet knowable *a priori*
(see Ichikawa and Jarvis 2009 and Malmgren 2011 for a discussion of
the content of such *a priori* justified judgments; for
literature on *a priori* knowledge, see BonJour 1998, BonJour
in BonJour & Devitt 2005 [2013]; Boghossian and Peacocke 2000;
Casullo 2003; Jenkins 2008, 2014; and Devitt 2014).


### 5.5 Testimony



Testimony differs from the sources we considered above because it
isn't distinguished by having its own cognitive faculty. Rather,
to acquire knowledge of *p* through testimony is to come to know
that *p* on the basis of someone's saying that *p*.
"Saying that *p*" must be understood broadly, as
including ordinary utterances in daily life, postings by bloggers on
their blogs, articles by journalists, delivery of information on
television, radio, tapes, books, and other media. So, when you ask the
person next to you what time it is, and she tells you, and you thereby
come to know what time it is, that's an example of coming to
know something on the basis of testimony. And when you learn by
reading the *Washington Post* that the terrorist attack in
Sharm el-Sheikh of 22 July 2005 killed at least 88 people, that, too,
is an example of acquiring knowledge on the basis of testimony.



The epistemological puzzle testimony raises is this: Why is testimony
a source of knowledge? An externalist might say that testimony is a
source of knowledge if, and because, it comes from a reliable source.
But here, even more so than in the case of our faculties, internalists
will not find that answer satisfactory. Suppose you hear someone
saying "*p*". Suppose further that person is in fact
utterly reliable with regard to the question of whether *p* is
the case or not. Finally, suppose you have no clue whatever as to that
person's reliability. Wouldn't it be plausible to conclude
that, since that person's reliability is unknown to you, that
person's saying "*p*" does not put you in a
position to know that *p*? But if the reliability of a
testimonial source is not sufficient for making it a source of
knowledge, what else is needed? Thomas Reid suggested that, by our
very nature, we accept testimonial sources as reliable and tend to
attribute credibility to them unless we encounter special contrary
reasons. But that's merely a statement of the attitude we in
fact take toward testimony. What is it that makes that attitude
reasonable? It could be argued that, in one's own personal
experiences with testimonial sources, one has accumulated a long track
record that can be taken as a sign of reliability. However, when we
think of the sheer breadth of the knowledge we derive from testimony,
one wonders whether one's personal experiences constitute an
evidence base rich enough to justify the attribution of reliability to
the totality of the testimonial sources one tends to trust (see E.
Fricker 1994 and M. Fricker 2007 for more on this issue). An
alternative to the track record approach would be to declare it a
necessary truth that trust in testimonial sources is at least prima
facie justified. While this view has been prominently defended, it
requires an explanation of what makes such trust necessarily prima
facie justified. Such explanations have proven to be
 controversial.[60]



## 6. The Limits of Cognitive Success


### 6.1 General Skepticism and Selective Skepticism



Much of modern epistemology aims to address one or another kind of
skepticism. Skepticism is a challenge to our pre-philosophical
conception of ourselves as cognitively successful beings. Such
challenges come in many varieties. One way in which these varieties
differ concerns the different kinds of cognitive success that they
target: skepticism can challenge our claims to *know*, or our
claims to *believe justifiably*, or our claims to have
*justification for believing*, or our claims to have any
*good reasons* for belief whatsoever. But another way in which
these varieties differ is in whether the skepticism in question is
fully general--targeting the possibility of enjoying any instance
of the relevant cognitive success--or is
selective--targeting the possibility of enjoying the relevant
cognitive success concerning a particular subject matter (e.g., the
past, the minds of others, the world beyond our own consciousness) or
concerning beliefs formed by a particular method (e.g., perception,
memory, reasoning, etc.). General skepticism and selective skepticism
pose very different sorts of challenges, and use very different kinds
of arguments. General skepticism is motivated by reasoning from some
apparently conflicting features of the kind of cognitive success in
question. For instance, a general skeptic might claim that
justification requires a regress of justifiers, but then argue that
this regress of justifiers cannot be contained in any finite
mind--and thus, the skeptic might conclude, no finite being can
be justified in believing anything. Alternatively a general skeptic
might claim that knowledge requires certainty, and that nobody can be
certain of something unless there is nothing of which she could be
even more certain--thus, the skeptic might conclude, we can know
virtually nothing (see Unger 1975).



Selective skepticism, in contrast, is typically motivated by appeal to
one or another skeptical hypothesis. A skeptical hypothesis is a
hypothesis according to which the facts that you claim to know
(whether these facts concern the past, or the mind of others, or the
mind-independent world, or what have you) may, for all you can tell,
be radically different from how they appear to you to be. Thus, a
skeptical hypothesis is a hypothesis that distinguishes between the
way things appear to you, on the one hand, and the way they really
are, on the other; and this distinction is deployed in such a way as
to pose a challenge to your cognitive success concerning the latter.
Here are some famous examples of skeptical hypotheses:


* All the other humans around me are automata who simply act exactly
as if they have thoughts and feelings.
* The whole universe was created no more than 5 minutes ago, replete
with fake memories and other misleading evidence concerning a distant
past.
* I'm lying in my bed dreaming everything that I'm aware
of right now.
* I'm a mere brain-in-a-vat (a BIV, for short) being
electrochemically stimulated to have all these states of mind that
I'm now having.



Skeptics can make use of such hypotheses in constructing various
arguments that challenge our pre-philosophical picture of ourselves as
cognitively successful. Consider, for instance, the BIV hypothesis,
and some ways in which this hypothesis can be employed in a skeptical
argument.



Here is one way of doing so. According to the BIV hypothesis, the
experiences you would have as a BIV and the experiences you have as a
normal person are perfectly alike, indistinguishable, so to speak,
"from the inside". Thus, although it appears to you as if
you are a normally embodied human being, everything would appear
exactly the same way to a BIV. Thus, the way things appear to you
cannot provide you with knowledge that you are not a BIV. But if the
way things appear to you cannot provide you with such knowledge, then
nothing can give you such knowledge, and so you cannot know that
you're not a BIV. Of course, you already know this much: if you
are a BIV, then you don't have any hands. If you don't
know that you're not a BIV, then you don't know that
you're not in a situation in which you don't have any
hands. But if you don't know that you're not in a
situation in which you don't have any hands, then you
don't know that you're not handless. And to not know that
you're not handless is simply to not know that you have hands.
We can summarize this skeptical argument as follows:




**The BIV-Knowledge Closure Argument** (BKCA)


* (C1) I don't know that I'm not a
BIV.
* (C2) If I don't know that I'm not
a BIV, then I don't know that I have hands.



Therefore:


* (C3) I don't know that I have
hands.




As we have just seen, (C1) and (C2) are very plausible
premises. It would seem, therefore, that BKCA is sound. If it is, we
must conclude we don't know we have hands. But surely that
conclusion can't be right: if it turns out that I don't
know that I have hands, that must be because of something very
peculiar about my cognitive relation to the issue of whether I have
hands--*not* because of the completely anodyne
considerations mentioned in BKCA. So we are confronted with a
difficult challenge: The conclusion of the BKCA seems plainly false,
but on what grounds can we reject
 it?[61]



Here are some other ways of using the BIV hypothesis to generate a
skeptical argument.




**The BIV-Justification Underdetermination Argument**
(BJUA)


* (U1) The way things appear to me could be
equally well explained by the BIV hypothesis as by my ordinary beliefs
that things appear to me the way they do because I perceive
mind-independent objects.
* (U2) If the way things appear to me could be
equally well explained by either of two hypotheses, then I am not
justified in believing one of those hypotheses rather than the
other.



Therefore:


* (U3) I am not justified in believing that I
perceive mind-independent objects.





**The BIV-Knowledge Defeasibility Argument** (BKDA)


* (D1) If I know that I have hands, then I know that
any evidence indicating that I don't have hands is misleading
evidence.
* (D2) If I know that some evidence is misleading, then
I know that I should disregard that evidence.



Therefore:


* (D3) If I know that I have hands, then I know that I
should disregard any evidence to the contrary.
* (D4) I do not know that I should disregard any
evidence to the contrary.



Therefore:


* (D5) I do not know that I have hands.





**The BIV-Epistemic Possibility Argument** (BEPA)


* (P1) It's at least *possible* that
I'm a BIV.
* (P2) If it's possible that I'm a BIV, then
it's possible that I don't have hands.
* (P3) If it's possible that I don't have
hands, then I don't know that I have hands.



Therefore:


* (P4) I don't know that I have hands.




Obviously, this list of skeptical arguments could be extended by
varying either (a) the skeptical hypothesis employed, or (b) the kind
of cognitive success being challenged, or (c) the epistemological
principles that link the hypothesis in (a) and the challenge in (b).
Some of the resulting skeptical arguments are more plausible than
others, and some are historically more prominent than others, but
there isn't space for a comprehensive survey. Here, we will
review some of the more influential replies to BKCA, BJUA, BKDA, and
BEPA.


### 6.2 Responses to the Closure Argument



Next, we will examine various responses to the
 BKCA
 argument. According to the first, we can see that
 (C2)
 is false if we distinguish between relevant and irrelevant
alternatives. An alternative to a proposition *p* is any
proposition that is incompatible with *p*. Your having hands and
your being a BIV are alternatives: if the former is true, the latter
is false, and *vice versa*. According to the thought that
motivates the second premise of the BIV argument, you know that you
have hands only if you can discriminate between your actually having
hands and the alternative of being a (handless) BIV. But, by
hypothesis, you can't discriminate between these. That's
why you don't know that you have hands. In response to such
reasoning, a relevant alternatives theorist would say that your
inability to discriminate between these two is not an obstacle to your
knowing that you have hands, and that's because your being a BIV
is *not* a *relevant* alternative to your having hands.
What would be a relevant alternative? This, for example: your arms
ending in stumps rather than hands, or your having hooks instead of
hands, or your having prosthetic hands. But these alternatives
don't prevent you from knowing that you have hands--not
because they are irrelevant, but rather because you can discriminate
between these alternatives and your having hands. The relevant
alternative theorist holds, therefore, that you do know that you have
hands: you know it because you can discriminate it from relevant
alternatives, like your having stumps rather than hands.



Thus, according to Relevant Alternatives theorists, you know that you
have hands even though you don't know that you are not a BIV.
There are two chief problems for this approach. The first is that
denouncing the BIV alternative as irrelevant is *ad hoc* unless
it is supplemented with a principled account of what makes one
alternative relevant and another irrelevant. The second is that
premise 2 is highly plausible. To deny it is to allow that the
following conjunction can be true:




**Abominable Conjunction**
  

I know that I have hands but I do not know that I am not a (handless)
BIV.




Many epistemologists would agree that this conjunction is indeed
abominable because it blatantly violates the basic and extremely
plausible intuition that you can't know you have hands without
knowing that you are not a
 BIV.[62]



Next, let us consider a response to BKCA according to which it's
not the second but the first premise that must be rejected. G. E.
Moore has pointed out that an argument succeeds only to the extent
that its premises are more plausible than the conclusion. So if we
encounter an argument whose conclusion we find much more implausible
than the denial of the premises, then we can turn the argument on its
head. According to this approach, we can respond to the BIV argument
as follows:




**Counter BIV**


* (~C3) I know that I have hands.
* (C2) If I don't know that I'm not a BIV, then I
don't know that I have hands.



Therefore:


* (~C1) I know that I am not a BIV.




Unless we are skeptics or opponents of closure, we would have to
concede that this argument is sound. It is valid, and its premises are
true. Yet few philosophers would agree that Counter BIV amounts to a
satisfying response to the BIV argument. It fails to explain
*how* one can know that one is not a BIV. The observation that
the premises of the BIV argument are less plausible than the denial of
its conclusion doesn't help us understand how such knowledge is
possible. That's why the Moorean response, unsupplemented with
an account of how one can know that one is not a BIV, is widely
thought to be an unsuccessful rebuttal of
 BKCA.[63]



We have looked at two responses to BKCA. The relevant alternatives
response implausibly denies the second premise. The Moorean response
denies the first premise without explaining how we could possibly have
the knowledge that the first premise claims we don't have.
Another prominent response, contextualism, avoids both of these
objections. According to the contextualist, the precise contribution
that the verb "to know" makes to the truth-conditions of
the sentences in which it occurs varies from one context to another:
in contexts in which the BIV hypothesis is under discussion, an agent
counts as "knowing" a fact only if she can satisfy some
extremely high (typically unachievable) epistemic feat, and this is
why (1) is true. But in contexts in which the BIV hypothesis is not
under discussion, an agent can count as "knowing" a fact
even if her epistemic position vis-a-vis that fact is much more
modest, and this is why (3), taken in isolation, appears false.



The contextualist literature has grown vastly over the past two
decades: different contextualists have different accounts of how
features of context affect the meaning of some occurrence of the verb
"to know", and each proposal has encountered specific
challenges concerning the semantic mechanisms that it posits, and the
extent to which it explains the whole range of facts about which
epistemic claims are plausible under which
 conditions.[64]


### 6.3 Responses to the Underdetermination Argument



Both the contextualist and the Moorean responses to
 BKCA,
 as discussed in the previous section, leave out one important detail.
Both say that one can know that one isn't a BIV (though
contextualists grant this point only for the sense of
"know" operational in low-standards contexts), but neither
view explains *how* one can know such a thing. If, by
hypothesis, a BIV has all the same states of mind that I
have--including all the same perceptual experiences--then
how can I be justified in believing that I'm not a BIV? And if I
can't be justified in believing that I'm not a BIV, then
how can I know that I'm not?



Of course, the question about how I can be justified in believing that
I'm not a BIV is not especially hard for externalists to answer.
From the point of view of an externalist, the fact that you and the
BIV have the very same states of mind need not be at all relevant to
the issue of whether you're justified in believing that
you're not a BIV, since such justification isn't fully
determined by those mental states anyway.



The philosophers who have had to do considerable work to answer the
question how I can be justified in believing that I'm not a BIV
have typically done this work not directly in reply to BKCA, but
rather in reply to BJUA.



What might justify your belief that you're not a BIV? According
to some philosophers, you are justified in believing that you're
not a BIV because, for instance, you know perfectly well that current
technology doesn't enable anyone to create a BIV. The proponent
of the BIV hypothesis might regard this answer as no better than the
Moorean response to BKCA: if you are allowed to appeal to (what you
regard as your) knowledge of current technology to justify your belief
that you're not a BIV, then why can't the Moorean equally
well rely on his knowledge that he has hands to justify his belief
that he's not a BIV? Philosophers who accept this objection, but
who don't want to ground your justification for believing that
you're not a BIV in purely externalistic factors, may instead
claim that your belief is justified by the fact that your own beliefs
about the external world provide a better explanation of your sense
experiences than does the BIV hypothesis (see Russell 1912 and Vogel
1990 for influential defenses of this argument against skepticism, and
see Neta 2004 for a rebuttal).


### 6.4 Responses to the Defeasibility Argument



The most influential reply to
 BKDA
 is to say that, when I acquire evidence that I don't have
hands, such evidence makes me cease to know that I have hands. On this
view, when I acquire such evidence, the argument above is sound. But
prior to my acquiring such evidence, (4) is false, and so the argument
above is not sound. Thus, the truth of (4), and consequently the
soundness of this argument, depends on whether or not I have evidence
that I don't have hands. If I do have such evidence, then the
argument is sound, but of course it has no general skeptical
implications: all it shows that I can't know some fact whenever
I have evidence that the fact doesn't obtain (versions of this
view are defended by Harman 1973 and Ginet 1980).



Plausible as this reply has seemed to most philosophers, it has been
effectively challenged by Lasonen-Aarnio (2014b). Her argument is
this: presumably, it's possible to have *more than
enough* evidence to know some fact. But if it's possible to
have more than enough evidence to know some fact, it follows that one
might still know that fact even if one acquires some slight evidence
against it. And yet, it would be wrong to leave one's confidence
entirely unaffected by the slight evidence that one acquires against
that fact: though the evidence might be too slight to destroy
one's knowledge, it cannot be too slight to diminish one's
confidence even slightly. So long as one could continue to know a fact
while rationally diminishing one's confidence in it in response
to new evidence, the most popular reply to the defeasibility argument
fails.



Other replies to the defeasibility argument include the denial of
premise
 (2),[65]
 the denial of (4) (McDowell 1982, Kern 2006 [2017]), and the claim
that the context-sensitivity of "knows" means that (4) is
true only relative to contexts in which the possibility of future
defeaters is relevant (see Neta 2002). But neither of these replies
has yet received widespread assent.


### 6.5 Responses to the Epistemic Possibility Argument



The most common reply to
 BEPA
 is either to deny premise (1), or to deny that we are justified in
believing that premise (1) is true. Most writers would deny premise
(1), and would do so on whatever grounds they have for thinking that I
can know that I'm not a BIV: knowing that something is not the
case excludes that thing's being epistemically possible for
 you.[66]



But a couple of influential writers--most notably Rogers
Albritton and Thompson Clarke (see Albritton 2011 and Clarke
1972)--do not claim that premise (1) is false. Rather, they deny
that we are justified in believing that premise (1) is true. According
to these writers, what normally justifies us in believing that
something or other is epistemically possible is that we can conceive
of *discovering* that it is true. For instance, what justifies
me in believing, say, that it's possible that Donald Trump has
resigned is that *I can clearly conceive of discovering* that
Donald Trump has resigned. But if I attempt to conceive of discovering
that I'm a BIV, it's not clear that I can succeed in this
attempt. I may conceive of coming upon some evidence that I'm a
BIV--but, insofar as this evidence tells in favor of the
hypothesis that I'm a BIV, doesn't it also undermine its
own credibility? In such a case, is there anything at all that would
count as "my evidence"? (see Neta forthcoming for an
elaboration of this point). Without being able to answer this question
in the affirmative, it's not clear that I can conceive of
anything that would amount to discovering that I'm a BIV. Of
course, from the fact that I cannot conceive of anything that would
amount to discovering that I'm a BIV, it doesn't follow
that I'm not a BIV--and so it doesn't even follow
that it's not possible that I'm a BIV. But, whether or not
it *is* possible that I'm a BIV, I can't be
justified in thinking that it is. And that's to say that I
can't be justified in accepting premise (1) of BEPA.