## 1. The Transcendental Deduction



The Transcendental Deduction (A84-130, B116-169) is
Kant's attempt to demonstrate against empiricist psychological
theory that certain *a priori* concepts correctly apply to
objects featured in our experience. Dieter Henrich (1989) points out
that Kant's use of '*Deduktion*' redeploys
German legal vocabulary; in Holy Roman Empire Law,
'*Deduktion*' signifies an argument intended to
yield a historical justification for the legitimacy of a property
claim. In Kant's derivative epistemological sense, a deduction
is an argument that aims to justify the use of a concept, one that
demonstrates that the concept correctly applies to objects. For Kant a
concept is *a priori* just in case its source is the
understanding of the subject and not sensory experience (A80/B106;
Strawson 1966: 86). The specific *a priori* concepts whose
applicability to objects of experience Kant aims to vindicate in the
Transcendental Deduction are given in his Table of Categories
(A80/B106); they are Unity, Plurality, and Totality (the Categories of
Quantity); Reality, Negation, and Limitation (the Categories of
Quality); Inherence and Subsistence, Causality and Dependence, and
Community (the Categories of Relation), and Possibility-Impossibility,
Existence-Nonexistence, Necessity-Contingency (the Categories of
Modality).



David Hume in effect denies that a deduction can be provided for a
number of metaphysical concepts - *ideas*, in his
terminology - including the ideas of personal identity, of
identity over time more generally, of the self as a subject distinct
from its perceptions, and of causal power or force (1739, 1748). In
Hume's view, a concept can only be validated by finding a
sensory experience, that is, an *impression*, in particular the
one that is the 'original' of that idea, which must
resemble that idea. But because, for example, any attempt to find an
impression of causal power turns out to be fruitless, Hume concludes
that this idea does not legitimately apply (1748: SS7). In
Kant's terminology, Hume is determining whether one might
provide an *empirical* deduction of the concept of causal power
(A85/B117), and from the failure of the attempt to do so, he concludes
that this concept lacks *objective validity*, that is, it does
not apply to the objects of our experience.



Hume's position on the deducibility of *a priori*
metaphysical concepts is Kant's quarry in the Transcendental
Deduction. But Kant concurs with Hume's proposal that no
empirical deduction can be supplied for such concepts. Instead, he
sets out to provide a different sort of justification for their use,
one that is *transcendental* rather than empirical. Such a
transcendental deduction begins with a premise about any possible
human experience, a premise to which reasonable participants in the
debate can be expected initially to agree, and then contends that a
presupposition and necessary condition of the truth of that premise is
the applicability of the *a priori* concepts in question to the
objects of experience. Kant's Transcendental Deduction features
a number of component transcendental arguments. Each begins with a
premise either about the self-attributability of mental items,
*apperception*, or else a premise about the necessity and
universality of some feature of our experience of objects. Kant'
strategy is to establish a theory of mental processing,
*synthesis*, by arguing that its truth is a necessary condition
for the truth of such a premise, and then to show that the *a
priori* concepts at issue - the categories - have an
essential role in this sort of mental processing. On a metaphysical
idealist interpretation of his position, the objects of experience
result from this mental processing, and it is due to the role that the
categories have in this processing that they correctly apply to
objects. In the Transcendental Deduction Kant would thus intend to
secure a normative claim, that the categories correctly apply to the
objects of our experience, by establishing a psychological theory
(Henrich 1989; Patricia Kitcher 1990: 2-29; for information on
related argumentative strategies in Kant's historical context,
see Kuehn 1997 and Dyck 2011). The Transcendental Deduction presents
general considerations supporting the applicability of all the
categories to the objects of our experience; it does not concentrate
on the applicability of specific categories. This more focused task is
taken up in various sections of the Analytic of Principles
(A130-235/B169-287).



In the *Metaphysical Deduction* (A66-83, B92-116)
Kant intends to derive the categories from the specific modes or forms
of any human thought about the world, the *logical forms of
judgment*. The Metaphysical Deduction has an essential role to
play in the Transcendental Deduction, and we will discuss this
argument at an appropriate juncture (when we reach SS19 of the
B-Deduction).



For Kant, the most significant rival theory of mental processing is
that of his target, Hume. Hume concurs that a theory of experience
requires an account of the processing of mental items, but he denies
that such an account demands *a priori* concepts or issues in
their legitimate applicability to experience. According to his theory,
*associationism*, our mental repertoire consists solely of
perceptions, all of which are sensory items - the more vivid
impressions, which constitute sensory experience, and their less vivid
copies, the ideas, which function in imagination, memory, reasoning,
and conceptualization (1748, SSSS2, 3). Association is the
process by which these perceptions are related and ordered. A
signature feature of association on Hume's view is that it
requires no resources distinct from the perceptions themselves. How
perceptions are ordered is solely a function of what perceptions alone
can provide. Significantly, a subject not constituted solely of
perceptions has no role in Hume's theory; the Humean subject is
just a collection of perceptions (1739: I, IV, vi). These last two
features in particular make Humean associationism a highly economical
theory, which provides it with an initial advantage over Kant's
more complex view. However, Kant contends that associationism cannot
account for the facts to which the premises of the Transcendental
Deduction appeal, and that synthesis by *a priori* concepts,
that is, the categories, is required in addition.



Kant characterizes synthesis as "the act of putting different
representations together, and grasping what is manifold in them in one
cognition" (A77/B103); it is a process that "gathers the
elements for cognition, and unites them to form a certain
content" (A78/B103). Synthesis takes multiple representations
- in Kant's terminology, a 'manifold' -
and connects them with one another to produce a single further
representation with cognitive content (Patricia Kitcher 1990, 2011).
This process employs concepts as modes or ways of ordering
representations. A claim critical to the Transcendental Deduction is
that it is the categories by means of which manifolds of our
representations are synthesized. Since the understanding of the
subject is the source of the categories, and also a faculty that
yields synthesis, the subject plays a crucial role in mental
processing. It is important for Kant's view on mental processing
that this subject is distinct from its representations, and this is
another respect in which it differs from Hume's theory.



This discussion will focus on the Transcendental Deduction in the
second edition of the *Critique of Pure Reason* (1787) -
the *B-Deduction* - thoroughly rewritten and rethought
relative to the *A-Deduction* of the first edition (1781). On
my reading, in SSSS16-20 of the B-Deduction Kant employs
a two-pronged strategy for defeating associationism and establishing
synthesis. The first, contained in SSSS15-16, is
designed to show that association cannot account for an aspect of
one's consciousness of one's self that Kant refers to as
*the consciousness of its unity*, and that synthesis is
required to provide this explanation. This type of argument he calls
an *argument from above*, signifying that it begins with a
premise about self-consciousness. Correlatively, in
SSSS17-20 we find an *argument from below*, by
which Kant intends to establish that synthesis by means of the
categories is needed as a necessary condition of how we represent
objects (the above/below terminology is derived from A119; for
relevant historical background, see Carl 1989, 1992). On several other
readings, as we shall see, the B-Deduction is a more unified argument.
There are reasons to accept and reasons to resist interpretations of
this kind.


### 1.1 Apperception and its Unity



The argument from above in SS16 can be divided into two stages.
The goal of the first is to establish the various components of
*the principle of the necessary unity of apperception*. The
second stage aims to show that synthesis is a necessary condition for
the aforementioned aspect of self-consciousness, which this principle
highlights. *Apperception* is the apprehension of a mental
state - a representation, in Kant's terminology - as
one's own; one might characterize it as the self-ascription or
self-attribution of a mental state (Strawson 1966: 93-4). In
Kant's conception, my apperception has *necessary unity*
since all of my representations *must* be grounded "in
pure apperception, that is, in the thoroughgoing *identity* of
the self in all possible representations" (B131-2,
emphasis mine). By this he means that:



> 
> (*The principle of the necessary unity of apperception*) It
> must be the case that each of my representations is such that I can
> attribute it to my self, a subject which is the same for all of my
> self-attributions, which is distinct from its representations, and
> which can be conscious of its representations (A116, B131-2,
> B134-5).
> 



One might note three aspects of the meaning of this principle. First,
as pointed out earlier, Kant maintains that the apperceiving subject
is not itself a collection of representations. Kant affirms that I
have no inner intuition of the subject (e.g. B157), and this claim
would conflict with the subject's being a collection of
representations, since he holds that I can intuit my representations
by inner sense (e.g. A33/B49). Also, in SS16 Kant remarks:
"through the 'I', as simple representation, nothing
manifold is given; only in intuition, which is distinct from the
'I', can a manifold be given" (B135). If he believed
the apperceiving subject to be a collection of representations, it
would be surprising for him to deny that anything manifold is given
through my representation of it. Second, my ability to attribute
representations to myself as subject of them is *pure*, as
opposed to *empirical* apperception. This means that I have
this ability not in virtue of Humean inner perception, or Kantian
inner intuition, but rather independently of any such empirical
faculties. However, Kant repeatedly affirms that the purity of this
apperception does not imply that the subject to which one's
representations can be attributed is intuited - represented as
an object - in a purely rational or *a priori* way (e.g.,
B406-9). Third, Kant states that pure apperception is
*original*, and the explication he provides is that "it
is that self-consciousness which, while generating the representation
'I think' ... cannot itself be accompanied by any
further representation" (B132). I cannot have an intuition or
any other type of representation of myself as apperceiving subject
other than by way of 'I think...'-type thoughts, and
hence these thoughts are the original representations of this subject
(e.g., A350). At the same time, by virtue of my capacity for
apperception, I can have a kind of propositional grasp of the
apperceiving subject; Kant affirms that in apperception, I am
conscious *that* I exist as subject (B157). (For recent
extensive discussions of Kant on self-knowledge, see Rosefeldt 2000,
Kitcher 2011, and Longuenesse 2017; cf. Howell 2001.)



Kant initiates the first stage of the argument in SS16 by
claiming:



> 
> It must be possible for the 'I think' to accompany all my
> representations; for otherwise something would be represented in me
> which could not be thought at all, and that is equivalent to saying
> that the representation would be impossible, or at least would be
> nothing to me. (B131-32)
> 



On one interpretation, the sense in which a representation would be
impossible or nothing to me if it could not accompanied with the
'I think' is simply that I could not then become conscious
of it (Guyer 1987: 139-44). It is credible that for any
representation of which I am conscious, I can attribute it to myself
as subject, assuming my mental faculties are in working order, and if
no controversial account of the nature of the subject is presupposed.
However, the claim that I can become conscious of *each* of my
representations, and that it is therefore possible for me attribute
each of them to myself as their subject, is likely false. Plausibly,
some of my representations are so thoroughly subconscious that I
cannot attribute them to myself, while they are nevertheless mine due
to the causal relations they bear to other representations and to
actions that are paradigmatically mine. Fortunately, however, the
premise that each of my representations is such that I can attribute
it to myself is not crucial for the argument from above. Rather, the
premise Kant ultimately singles out is less committed, and focuses
more specifically on the identity or sameness of the subject of
different self-attributions, and my being conscious of this
identity.



A number of interpreters, including Robert Howell (1992) and James van
Cleve (1999), maintain that the argument of SS16 requires a
premise affirming the possibility of my being *simultaneously*
conscious of the multiple elements of my representations, and that the
implausibility of this premise jeopardizes the soundness of the
argument. Howell's specific objection is that Kant does not
establish the following crucial premise:



> 
> (S) All of the elements of the manifold of *i* (where
> *i* is some arbitrary intuition) are such that H is or can
> become conscious, in thought, that all of those elements, taken
> together, are accompanied by the *I think*.
> 



(S) asserts that all of the individual elements of the selected
intuition are such that the subject is or can become conscious of them
simultaneously. In Howell's interpretation, only if the elements
of an intuition together and at the same time are accompanied by the
same *I think* will it be plausible that the subject must
synthesize these elements (Howell 1992: 162). On van Cleve's
reading, it is required that for any intuition that I have, I actually
become simultaneously conscious of its elements. If this
co-consciousness were just merely possible, Kant could only conclude
is that the resulting representation is only possibly subject to the
categories (van Cleve 1999: 84). On an interpretation of this type,
the mechanism of the argument of SS16 is to adduce a kind of unity
or combination that my representations actually exhibit, and then to
argue that this unity requires synthesis by means of the categories as
a condition or for its explanation. Kant is thus read as contending
that actual co-consciousness is a type of unity that demands synthesis
by means of the categories, and that any variety of unity short of
co-consciousness will be inadequate to establishing this objective of
the Deduction.



Howell points out that (S) contrasts with a weaker claim:



> 
> (W) Each element of the manifold of *i* is such that H is or
> can become conscious, in thought, that the *I think*
> accompanies that element. (Howell 1992: 161)
> 



which allows that the individual elements of the intuition are such
that the subject can only become conscious of each separately, perhaps
in turn. He contends, however, that the unity expressed by (W) is
insufficient to generate this need for synthesis. If I am merely
(possibly or actually) serially conscious of the elements of an
intuition, it won't be required that I synthesize them into a
unified intuition. Howell goes on to argue that while (W) is credible,
Kant cannot in fact establish (S); it is implausible that such
co-consciousness for any arbitrary intuition is actual or even
genuinely possible for us. Consequently, the soundness of this
argument, and the overall argument of the B-Deduction is
imperiled.



However, it may be that only the weaker premise (W) is required for
the success of the argument of SS16. First, although the
co-consciousness premise (S) might be *suggested* in SS16
by the following text:



> 
> That relation comes about, not simply through my accompanying each
> representation with consciousness, but only in so far as I conjoin one
> representation with another, and am conscious of the synthesis of
> them. (B133)
> 



that claim is not uncontroversially made here. For by the assertion
that I "am conscious of the synthesis of them," i.e., of
these representations, Kant may mean only that I am conscious that
they stand in a certain intimate relation to one another, for
instance, that that they are integrated with each other in a way
distinct from how mine are integrated with yours, which does not
require co-consciousness (Pereboom 1995).



Moreover, it might well be that the argument of SS16 features a
subtlety that obviates the need for actual co-consciousness. The text
indicates that the argument crucially turns on the claim that only
*a priori* synthesis - that is, synthesis by *a
priori* concepts - can explain *how I might represent the
identity of my apperceptive consciousness* (B133) or *how I
might represent the identity of the apperceiving subject* (B135)
for different elements of the manifold of intuition to which I can
attach the *I think*. The inadequacy Kant claims for
"empirical consciousness," that is, for consciousness
according to Humean psychological theory, is that "it is in
itself dispersed (*an sich zerstreut*) and without relation to
the identity of the subject (*und ohne Beziehung auf die
Identitat des Subjects*)" (B133). One implication of
this passage is that Hume's theory does not have the resources
needed to explain how I can self-attribute various of my
representations or their elements to a subject that is both conscious
of them and the same subject for each act of their self-attribution.
This objection does not beg the question in Kant's dispute with
Hume, since it assumes only a claim that uncommitted and reasonable
participants in this discussion would not want to initially deny, that
the conscious subject of these apperceptive self-attributions is the
same. Hume's theory lacks the resources to account for this
identity. Hume himself provides no account of apperception, but
possibilities for a Humean account are that apperceptive consciousness
amounts to perceptions that are intrinsically self-conscious, or else
consists in perceptions of perceptions. But intrinsically
self-conscious perceptions would be distinct from one another, as
would perceptions of perceptions; and thus they too would be
"dispersed" (B133), and share no common element. Hume
might propose to explain our sense of the identity of the conscious
subject of different self-attributions by the intrinsically
self-conscious perceptions or the perceptions of perceptions being
components of a single causally coherent bundle. However, this bundle
would not itself be conscious of perceptions. Consciousness of
perceptions would instead be an intrinsic feature of an individual
self-conscious perception or a feature of individual perceptions of a
perception. In Kant's conception, by contrast, accounting for
our sense of the identity of the conscious subject of different
self-attributions requires that this subject be distinct from its
representations.



The second stage of the argument of SS16 highlights another
implication of the claim that "the empirical consciousness,
which accompanies different representations, is dispersed and without
relation to the identity of the subject" (B133): that
Hume's theory lacks the resources to account for my
*representation-relation* to the identity of the subject; that
is, this view cannot explain how I can "represent to myself the
*identity of the consciousness in [i.e. throughout] these
representations*" (B133) (for an opposing view see Dickerson
2004: 95-8). We might imagine several kinds of explanation for
my representation of this identity. One candidate is that inner sense
allows me to represent this identity: the way I represent the sameness
of the subject is akin to how I commonly represent the identity over
time of ordinary objects - by a cognitive sensitivity to
similarities among the intrinsic properties represented. However, Kant
and Hume concur that this is not how I might represent the identity of
the apperceiving subject, since they agree that by inner sense I
cannot represent any intrinsic properties of such a subject. A second
kind of explanation, which Kant endorses, is that I have an indirect
way of representing this identity. This representation must instead
depend on my apprehending a feature of my representations (or elements
of them) (Allison 1983: 142-4; Guyer 1977: 267, 1987:
133-39; Patricia Kitcher 2011: 147). The appropriate feature is
a type of unity or ordering of these states. The idea is that if the
representations I can attribute to myself possess a unity of the right
kind, and if I apprehend or am cognitively sensitive to this unity,
then I will be able to represent the apperceiving subject of any one
of them as identical with that of any other.



Thus my representation of the identity of the subject comes about
"only in so far as I conjoin one representation with another,
and am conscious of the synthesis of them" (B133). This
consciousness is profitably interpreted as conscious awareness not of
the act or process of synthesis itself, but rather of the unity that
is its outcome (Strawson 1966: 94-6; Dicker 2004: 133-4)).
What sort of unity must I consciously recognize among my
representations that would account for my representation of this
identity? Note that it is not plausibly co-consciousness, for I
represent the subject as identical for self-attributed representations
that are not co-conscious, so actual co-consciousness could not
explain generally how I represent this sort of identity. A credible
alternative is that the unity consists in certain intimate ways in
which representations in a single subject are typically related.
Arguably, the essential feature of this unity is that a single
subject's representations be inferentially and causally
integrated to a high degree, and in this respect they are unified in a
way in which representations possessed by discrete subjects are not.
Alternatively, several commentators have argued that the relevant
unity might be a temporal order among my representations, thereby
linking the B-Deduction with the arguments of the Second Analogy and
the Refutation of Idealism (Guyer 1977: 267; Dicker 2004:
137-44). A concern about this route is that a cognitive
sensitivity to the time-ordering of representations does not obviously
facilitate our representing them as belonging to a single subject
(Brueckner 1984: 199-208). By contrast, when mental states fail
to exhibit inferential and causal integration, as in the case of
multiple-personality disorder, we have a tendency to posit multiple
subjects, while we do not do so when such integration is present.



In Kant's view, the candidates for explaining how this kind of
unity comes to be, or, less ambitiously, for explaining my ability to
recognize this sort of unity, are association and synthesis. At this
point he appears to suppose that because Hume's psychological
theory has already been ruled out, synthesis is the only remaining
option. So for me to represent the identity of the subject of
different self-attributions, I must generate or at least recognize the
right sort of unity among these representations, and synthesis must be
invoked to account for this unity. Thus Kant contends that this
combination "is an affair of the understanding alone, which
itself is nothing but the faculty of combining *a
priori*" (B134-5. Since the understanding provides
concepts for synthesis, and because for synthesis to be *a
priori* is, at least in part, for it to employ *a priori*
concepts, Kant is contending here that synthesis by means of *a
priori* concepts is required to account for the unity in
question.



Here is an austere representation of the structure of the argument so
far:


1. I am conscious of the identity of myself as the subject of
different self-attributions of mental states. (premise)
2. I am not directly conscious of the identity of this subject of
different self-attributions of mental states. (premise)
3. If (1) and (2) are true, then this consciousness of identity is
accounted for indirectly by my consciousness of a particular kind of
unity of my mental states. (premise)
4. This consciousness of identity is accounted for indirectly by my
consciousness of a particular kind of unity of my mental states. (1,
2, 3)
5. If (4) is true, then my mental states indeed have this particular
kind of unity. (premise)
6. This particular kind of unity of my mental states cannot be
accounted for by association. (5, premise)
7. If (6) is true, then this particular kind of unity of my mental
states is accounted for by synthesis by *a priori* concepts.
(premise)
8. This particular kind of unity of my mental states is accounted for
by synthesis by *a priori* concepts. (6, 7)



Premise (1) is intended as a claim the skeptic about the legitimate
applicability of *a priori* concepts will at least initially
accept. The crucial necessary conditions, expressed by (3) and (7),
are necessary conditions of only possible explanation. However, Paul
Guyer forcefully argues that establishing the need for synthesis by
means of *a priori* concepts would require ruling out the
alternative explanation that empirical information and concepts
derived from it is sufficient to account for the recognition of the
unity at issue (Guyer 1987:146-7). And in his view it remains
open, given what Kant has shown, that this recognition requires only
awareness of information derived from inner sense or introspective
experience. Kant does not attempt at this point in the argument to
rule out such a rival empiricist hypothesis, but he arguably would
need to do so to establish the need for *a priori* synthesis.
To advance his claims, one might appeal to features of this unity that
would render such an empiricist account inadequate. As we shall see,
Kant employs this tactic in the next phase of the argument, which
introduces his account of our representations of objects.


### 1.2 Representations of Objects and the Single-Substantive-Premise Interpretation of the B-Deduction



According to one widespread reading of the B-Deduction,
SSSS15-20 comprise a an argument whose only assumption
is the premise about self-consciousness that Kant defends in SS16.
Strawson, for example, is a proponent of such an interpretation
(1966), as are Robert Paul Wolff (1963), Jonathan Bennett (1966),
Henry Allison (1983), Edwin McCann (1985), and Dennis Schulting
(2012a). Demonstrating that we represent objects or an objective world
has a key role in most versions of this reading. On Strawson's
interpretation, for instance, "the fact that my experience is of
a unified objective world is a necessary consequence of the fact that
only under this condition could I be conscious of my diverse
experiences as one and all my own" (1966: 94). Some interpreters
dissent; Karl Ameriks, for example, contends that Strawson's
conception of the Deduction is motivated by a desire to see it as
showing that the skeptic about the external world is mistaken, while
in fact refuting this sort of skeptic is not one of Kant's aims
for this argument (Ameriks 1978; also Allais 2011, 2015). Patricia
Kitcher (2011: 115-18) argues against the single premise about
self-consciousness interpretation on historical and textual
grounds.



An uncontroversial role of SS17 is to provide a characterization
of an object, or more to the point, of a representation of an object,
that facilitates a challenge to Humean associationism. Kant's
proposal is that an object is "that in the concept of which a
manifold of a given intuition is united" (B137). Here
'object' should be read in the broad sense of
*objective feature of reality* - a feature whose
existence and nature is independent of how it is perceived (B 142;
Bird 1962/1973 130-31; Strawson 1966: 98-104; Guyer 1987:
11-24). Allison is a proponent of the view that SS17 contain
not only this challenge to Hume, but also an attempt to demonstrate
that we represent objects on the basis of the conclusions about
self-consciousness established in SS16. This interpretation is a
component of Allison's broader vision of the B-Deduction,
according to which Kant demonstrates that the unity of apperception
entails that we represent objects, and, conversely, that our
representing objects entails the necessary unity of apperception
(Allison 1983: 144ff; 2015: 352-55; 2015: 335-55, esp. 352)
Indeed, the crucial claim for Allison's interpretation is that
the unity of apperception is not only a necessary but also sufficient
condition for our representing of objects. This he calls the
*reciprocity thesis*. Other commentators, including Richard
Aquila (1989: 159), Howell (1992: 227-8) and Schulting (2012a)
agree that the B-Deduction features the reciprocity thesis and an
attempt to establish its truth, while Ameriks (1978) disagrees. On an
account of the sort Ameriks favors, the unity of apperception, and
more exactly, the synthesis that explains our consciousness of the
identity of the subject, is only a necessary condition for the
representation of objects (cf. Allais 2011).



Allison's interpretation is attractive particularly because it
promises leverage against the skeptic who denies that we represent
objects, and also because this leverage is generated by premises about
self-consciousness that this skeptic is likely to accept.
Nevertheless, there are textual and charitable reasons to resist this
reading (Ameriks 1978, Pereboom 1995; Patricia Kitcher 2011:
115-60; Vinci 2014: 193-94). First of all, in
SSSS18-20 Kant makes significant assumptions about
features of our representations of objects that exceed anything that
he has argued for in SS17 or earlier. In particular, SS18 he
assumes that our representations of objects manifest a certain kind of
necessity and universality, and this he does not purport to establish
in SS17 or earlier. Moreover, in the summary of the preceding
steps of the B-Deduction in SS20 Kant does not include premises
from SSSS15-16. What we actually encounter in SS20
indicates that Kant intends SSSS17-20, with some help
from SS13, to constitute a single, self-contained argument that
does not depend on the conclusions about self-consciousness developed
in SSSS15-16.



On Allison's conception, the argument from the unity of
apperception (or, equivalently, from the unity of consciousness) for
our representing objects occurs in the following passage:



> 
> (A) Understanding is, to use general terms, the faculty of cognitions
> (*Erkenntnisse*). They consist (*bestehen*) in the
> determinate relation of given representations to an object: and an
> object is that in the concept of which the manifold of a given
> intuition is united. Now all unification of representations demands
> unity of consciousness in the synthesis of them. Consequently it is
> the unity of consciousness that alone constitutes the relation of
> representations to an object, and therefore their objective validity
> and the fact that they are cognitions (*Erkenntnisse*): and
> upon it therefore rests the very possibility of the understanding.
> (B137)
> 



Allison himself presents a problem for his interpretation of this
passage. He contends, first of all, that the reciprocity thesis is
encapsulated in this sentence:


1. It is the unity of consciousness that alone constitutes
[*ausmacht*] the relation of representations to an object, and
therefore their objective validity.



and that Kant presents (1) as a direct consequence of the premise
that


2. all unification of representations demands unity of consciousness
in the synthesis of them.



Allison points out that on this reading Kant's reasoning appears
to involve a *non sequitur*, since (2) supports only
Kant's having in mind that the unity of consciousness is a
necessary condition for the representation of an object, and not for
its also being a sufficient condition. Howell raises a similar
concern: "In SS17 Kant simply does not make this inference
clear, and an air of blatant fallacy hovers over this part of his
reasoning" (Howell 1992: 228; for an opposing view see Keller
1998: 80). But Ameriks argues that the B-Deduction should not be
interpreted as providing an argument for the sufficiency claim, and a
respectable case can be made for his reading (Ameriks 1978; Pereboom
1995; Patricia Kitcher 2011: 115-60).



Allison and Howell both argue that (1) should be read as a statement
of the sufficiency claim. Now in (A) Kant contends that cognitions of
objects consist in a determinate relation of representations to
objects, and as (1) indicates, this relation is constituted or
produced by a synthesis that essentially involves the unity of
consciousness. However, (1) does not indicate that the synthesis that
involves unity of consciousness cannot occur without its resulting in
a relation of a representation to an object. By analogy, the smelting
and molding of steel are processes that constitute or produce steel
girders, but from this one should not conclude that the processes of
smelting and molding steel cannot take place without the production of
steel girders. Just as producing steel girders also requires molds of
particular shapes, so producing representations of objects might
require, in addition to the synthesis that involves the unity of
consciousness, particular concepts of objects.



If the sufficiency claim, and with it the reciprocity thesis, is
denied, we need an alternative account of how SS17 functions in
the overall argument of the B-Deduction. It may be that the role of
this section is largely to provide a characterization of an object
that has a key role in the ensuing challenge to Humean associationism,
and thereby initiates an argument from below. Kant's proposal is
that an object is "that in the concept of which a manifold of a
given intuition is united" (B137). The subsequent claim is that
the unification of a manifold requires synthesis; immediately
following the characterization of an object he states that "all
unification of representations demands unity of consciousness in the
synthesis of them" (B137). It seems consistent with these texts
that Kant's characterization of an object is designed just to
present his anti-Humean theory of the mental processing required for
representing objects, and that the subsequent claim for the need for
synthesis does not express a view he expects us to accept without
further argument, but rather one he aims to confirm in
SSSS18-20. If this argument succeeds, it will turn out
that the *a priori* synthesis required to account for the
features of our representations of objects Kant singles out is the
same process that yields my consciousness of the identity of myself as
subject of different self-attributions.


### 1.3 Universality and Necessity in our Experience of Objects



In SS18 Kant draws our attention to certain features of our
representations of objects that, in his view, will serve to defeat
associationism and establish *a priori* synthesis:



> 
> The transcendental unity of apperception is that unity through which
> all the manifold given in an intuition is united in a concept of the
> object. It is therefore entitled objective, and must be distinguished
> from the subjective unity of consciousness... Whether I can
> become *empirically* conscious of the manifold as simultaneous
> or as successive depends on circumstances and empirical conditions.
> Therefore, the empirical unity of consciousness, through association
> of representations, itself concerns an appearance, and is wholly
> contingent... Only the original unity is objectively valid: the
> empirical unity of apperception,... which... is merely
> derived from the former under given conditions *in concreto*,
> has only subjective validity. One person connects the representation
> of a certain word with one thing, the other [person] with another
> thing; the unity of consciousness in that which is empirical is not,
> as regards what is given, necessarily and universally valid.
> (B139-40)
> 



For Kant, a defining feature of our representations of objects is
their objective validity. For a representation to be objectively valid
it must be a representation of an objective feature of reality, that
is, a feature whose existence and nature is independent of how it is
perceived (Guyer 1987:11-24). In this argument, it appears that
Kant just assumes that the representations that make up experience are
objectively valid. He then aims to establish that association is
inadequate because it can yield only representations that are not
objectively valid. In the above passage, Kant contends that our
objectively valid representations must in a sense be necessary and
universal. However, the empirical unity of consciousness, which
involves an ordering of representations achieved by association, can
only be non-universal, contingent, and hence merely subjectively
valid, by contrast with the transcendental unity of apperception,
which involves an ordering that is universal and necessary, and is
therefore objectively valid. In Kant's conception, it is the
fact that the transcendental unity of apperception is generated by
*a priori* synthesis that allows it to yield an ordering that
is universal, necessary, and objectively valid. (Ameriks 1978,
Pereboom 1995, Patricia Kitcher 2011: 115-60; Allais 2011, 2015;
Vinci 2014). On Lucy Allais's proposal, empirically we are
acquainted with objects, but absent a priori synthesis, empirical
representations would be of objects that are indeterminate with
respect to multiple possible ways of conceptualizing and individuating
them. Only with a priori synthesis is the representation of
determinate objects possible. The concept of cause has a key role
here, since determinacy is paradigmatically a function of represented
causal unity of objects (Allais 2015: 275-85; cf. Beck 1978;
Vinci 2014: 134-44). This determinacy, by virtue of a shared
scheme of a priori concepts, yields the universality and necessity
Kant has in mind.



To illustrate and support these claims, Kant invokes examples of the
ordering of phenomena in time that also have the key role in the
discussion of the Second Analogy (cf. Guyer 1987: 87-90; Dicker
2004: 137-44). There Kant argues that our representations,
considered independently of their content, are always successive. For
example, when I view the front, sides, and back of the house when
walking around it, and when I watch a boat float downstream, my
representations of the individual parts and states occur successively.
The content of these successive representations, however, can be
represented as either determinately and objectively successive or as
determinately and objectively simultaneous. And as it in fact turns
out, despite the representations in each of these sequences being
subjectively successive, we represent the parts of the house as
objectively simultaneous, and the positions of the boat as objectively
successive. How might we account for this difference in objectivity
despite the similarity in subjectivity? (Melnick 1973: 89)



The important clue for answering this question is that these
representations of objective simultaneity and succession are universal
and necessary. It is the universality and necessity of our
representing the parts of the house as simultaneous that accounts for
our representing them as objectively simultaneous, and the
universality and necessity of our representing the positions of the
boat as successive that accounts for our representing them as
objectively successive. Association is inadequate for accounting for
this objectivity because it is incapable of yielding such universality
and necessity, a defect not shared by synthesis.



A first approximation of the import of 'universal' in the
house example is:



> 
> (U) Any human experience of the parts of the house is an experience of
> these parts as objectively simultaneous.
> 



The addition of necessity has the following effect on (U):



> 
> (U-N, first pass) Necessarily, any human experience of the parts of
> the house is an experience of these parts as objectively simultaneous.
> 



This claim would be resisted by Hume if the necessity were specified
as ranging over all possible circumstances, for Hume's theory
would allow for the possibility of a deviant ordering in unusual
empirical conditions. But (U-N, first pass) can be reformulated more
precisely as



> 
> (U-N) Necessarily, if empirical conditions are normal, any human
> experience of the parts of the house is an experience of these parts
> as objectively simultaneous.
> 



Kant's view is that given only the resources of association, the
truth of (U-N) cannot be explained. The reason is "whether I can
become empirically conscious of the manifold as simultaneous or as
successive depends on circumstances or empirical conditions,"
and so "the empirical unity of consciousness, through
association of representations, itself concerns an appearance, and is
wholly contingent" (B139-40). Association cannot explain
the truth of (U-N), for given only the resources of association, the
parts of the house will not necessarily or universally be represented
as objectively simultaneous even supposing only normal empirical
conditions. Kant asks us to consider an activity, word association,
which functions as a paradigm for association. Word association,
familiarly, does not yield universal and necessary patterns;
"one person connects the representation of a certain word with
one thing, the other [person] with another thing..."
(B140). Hume's own paradigm for association in is the relations
among parts of a conversation (1748: SS3). In such conversations,
people make different associations in the same circumstances.
Kant's point is that if the very paradigms for association fail
to exhibit the sort of necessity and universality at issue, then the
hypothesis that association is powerful enough to yield such an
ordering of representations - wherever we find it - is
ruled out. (Pereboom 1995; Dickerson 2004: 170-77; for an
account of a more general relationship in Kant between universality
and necessity on the one hand and apriority on the other, see Smit
2009).



Here we should see Kant as advancing his claim for the applicability
of the categories by ruling out association as an explanation for
(U-N). The structure of this (part of the) argument can be represented
as follows:


9. We have representations of objects, i.e., of objectively valid
phenomena. (premise)
10. All of our representations of objects are (in part) of universal
and necessary features of experience. (9, premise)
11. Necessary and universal features of experience cannot be explained
by association. (premise, from reflection on the nature of
association))
12. If (10) and (11) are true, all of our representations of objects
require a faculty for ordering mental states distinct from
association. (premise)
13. All of our representations of objects require a faculty for
ordering mental states distinct from association. (11, 12)
14. If (13) is true, all of our representations of objects require a
faculty for synthesis by *a priori* concepts. (premise)
15. All of our representations of objects require a faculty for
synthesis by *a priori* concepts. (13, 14)



We can expand (15) to explicitly note the link to the argument from
above:




|  |  |
| --- | --- |
| 15\*. | All of our representations of objects require a faculty for
synthesis by *a priori* concepts, the same faculty required to
account for my consciousness of the identity of myself as subject of
different self-attributions of mental states. (1-8, 13, 14) |



To this we can add the final moves, which are explained in the
subsequent sections of the B-Deduction:


16. Insofar as our representations of objects require a faculty for
synthesis by *a priori* concepts, certain *a priori*
concepts - the categories - legitimately apply to these
objects. (premise)


3. We have representations of objects, and they are all such that the
categories legitimately apply to these objects. (9, 15, 16)



The key necessary conditions, expressed by (12) and (14), like those
of the argument from above, are necessary conditions of only possible
explanation.



Guyer objects that at various places in the Transcendental Deduction
Kant illegitimately assumes knowledge of necessity, and perhaps this
argument falls to such a concern (Guyer 1987: 146-7). While this
concern has the potential of weakening Kant's argument, perhaps
Hume would not deny the necessity under consideration at this point in
the argument. Hume does maintain that it is in some sense impossible,
given an experience of constant conjunction, that the mind not be
carried from an impression of the first conjunct to an idea of the
next:



> 
> ... having found, in many instances, that any two kinds of
> objects, flame and heat, snow and cold, have always been conjoined
> together; if flame or snow be presented anew to the senses, the mind
> is carried by custom to expect heat or cold, and to *believe*,
> that such a quality does exist, and will discover itself upon a nearer
> approach. This belief is the necessary result of placing the mind in
> such circumstances. It is an operation of the soul, when we are so
> situated, as unavoidable as to feel the passion of love, when we
> receive benefits; or hatred, when we meet with injuries. (1748:
> SS5)
> 



Thus Hume himself contends that given certain specific empirical
circumstances, a particular type of ordering of perceptions in a sense
necessarily comes about.



A further concern of Guyer's is that Kant assumes without
defense that all knowledge of necessity is grounded in *a
priori* concepts. But, in response, perhaps we need not interpret
Kant as arguing directly from (U-N) to the claim that the categories
correctly apply to objects in our experience. Rather, we might see him
as advancing his claim for the applicability of the categories by
ruling out association as an explanation for (U-N). This transition
can be divided into three steps:


1. To explain the truth of (U-N), we must have a mental faculty other
than association for ordering representations.
2. This faculty does not consist solely of sensory items.
3. This faculty must employ *a priori* concepts, the
categories in particular.



The challenge Kant issues is to explain why, under normal conditions,
the ordering in question is universal and necessary. Part of the best
explanation, he believes, is (a), that we must have a faculty for
ordering the representations. Hume might agree with this conclusion,
supposing a sufficiently thin conception of 'faculty'. Yet
he would deny (b), that this faculty does not consist solely of
sensory items. Kant argues that the Humean proposal for a faculty that
consists solely of sensory items, the faculty of association, cannot
account for the truth of propositions such as (U-N), for the very
paradigms of association, such as word association, and the
association of topics in a conversation, do not exhibit the requisite
universality and necessity. The alternative that can account for the
truth of propositions such as (U-N) involves affirming (c), that the
faculty in question must be one that employs the categories.



The associationist might counter that sensory experience is
sufficiently uniform for association to produce the universalities and
necessities at issue. Perhaps Kant is too quick to conclude that the
argument from universality and necessity is decisive, for in addition,
associationist objections of this sort must be answered - as
contemporary critical discussions of proposals for innate concepts
indicate (Pereboom 1995: 31-3). But this does not detract from
the anti-associationist force provided by the sorts of universalities
and necessities Kant has in mind, and this fact is recognized by the
contemporary discussion.


### 1.4 Logical Forms of Judgment and the Categories



In SSSS19-20, Kant contends that the vehicle that brings
about the synthesis at issue is judgment, and that this vehicle
employs certain forms of judgment, which are in turn intimately
related to the twelve categories. By connecting synthesis to judgment
in this way, and the forms of judgment to the categories, Kant aims to
show that we must employ the categories in the synthesis of our
experience of objects.



In SS19, Kant argues that there must be a certain way in which
each of my representations is unified in the subject, and he
identifies this way with judgment: "I find that a judgment is
nothing but the manner in which given cognitions are brought to the
objective unity of apperception" (B141). Judgment, Kant
proposes, is objectively rather than subjectively valid, and hence
exhibits the type of universality and necessity that characterizes
objective validity (B142). He then claims that without synthesis and
judgment as its vehicle, an ordering of representations might reflect
what appears to be the case, but it would not explain how we make
distinctions between objective valid phenomena (i.e., objects) and the
subjective states they induce (e.g, Allison 2015: 363-69; Sethi
2020).



In SS20, Kant ties this notion of judgment to the twelve forms of
judgment presented in the Metaphysical Deduction (A70/B95), and he
then connects these forms of judgment to the twelve categories
(A76-83/B102-9). The claim has often been made that the
links Kant specifies between synthesis and judgment, judgment and the
forms of judgment, the forms of judgment and the categories are not
sufficiently supported. Guyer, for example, argues that Kant has not
adequately established the last of these connections, that although
Kant claims that the categories are simply the forms of judgment as
they are employed in the synthesis of representations in an intuition
(A79/B104-A80/B105, B143), he has failed to make this claim
plausible (Guyer 1987: 94-102). It is fair to say that these
concerns have merit. Kant's assertions about these ties remain
more obscure than the preceding part of the Transcendental Deduction,
and it continues to be a serious challenge for interpreters to clarify
and vindicate them.



Beatrice Longuenesse (1998), in her interpretation of the
Metaphysical Deduction, takes up this challenge. In her view, the
faculty at issue in the production and use of concepts, the
understanding, is the power to judge (*Vermogen zu
Urteilen*), which is ultimately a disposition or a
*conatus* to make judgments and to shape how we are affected so
that we can make them (Longuenesse 1998: 208, 394). The logical forms
of judgment are in essence the forms of combination of concepts in
judgments. One such form is the categorical, which is the form of
subject-predicate judgments; another is the hypothetical, the form of
conditional judgments. Kant contends that the logical form of a
judgment is what makes it capable of truth or falsity, for by means of
such a form a judgment can constitute a relation of a subject's
representations to an objective feature of reality (Longuenesse 2000,
93-4). For instance, by its categorical form, the judgment
'the boat is moving' can constitute the relation of my
representations of a boat and of motion to an objectively existing
boat in motion, and as a result this judgment can be true or
false.



One role of the logical forms of judgment is in the process of
analysis, by which the objects we intuit are subsumed under concepts.
What results from this process is a judgment that expresses what Kant
calls an *analytic unity* - paradigmatically, the unity
in the subsumption of several intuited objects under a single concept.
But a logical form of judgment can also function in a different role:
in the synthesis of a manifold of an intuition. The result in this
case is a *synthetic unity*, the unity of a synthesized
multiplicity of representations in a single intuition. The
understanding, as the power to judge, functions in each of these two
roles; "the same function that gives unity to concepts in
judgment, also gives unity to the mere synthesis of representations in
intuition" (A79/B104-5). In its synthetic role, the
understanding adds content to the forms of judgment:



> 
> The same understanding, and indeed by means of the very same actions
> through which it brings the logical form of judgment into concepts by
> means of the analytical unity, also brings a transcendental content
> into its representations by means of the synthetic unity of the
> manifold in intuition in general. (A79/B105)
> 



The addition of such transcendental content turns the form of judgment
into a category. This content is a feature of the forms of intuition,
space and time, which are called upon when the power to judge sets out
to unify a manifold of intuition (B128-9). The categories
- more precisely, the versions of the categories that are
schematized for our way of cognizing (A137/B176ff) - are thus
generated from the forms of judgment in the process of synthesizing
intuitions by the addition of spatial and temporal content. For
example, generated from the categorical form of judgment by the
addition of such content is the category of substance, and generated
from the hypothetical form of judgment in this way is the category of
cause. (For beings possessing the power of understanding but with
different forms of intuition, the categories would be schematized
differently from ours.)


### 1.5 The Second Step of the B-Deduction



In SS20 Kant, draws a conclusion from the considerations he has so
far advanced: "Consequently, the manifold in a given intuition
is necessarily subject to the categories" (B143). One might
think that this is precisely what Kant intended to establish in the
Transcendental Deduction, and thus that the argument is brought to an
end in SS20. However, in SS21 he indicates that the
Transcendental Deduction is not yet complete: "Thus in the above
proposition a beginning is made of a deduction of the pure concepts of
understanding" (B144). Kant goes on to explain:



> 
> In what follows (cf. SS26) it will be shown, from the mode in
> which the empirical intuition is given in sensibility, that its unity
> is no other than that which the category (according to SS20)
> prescribes to the manifold of a given intuition in general. Only thus,
> by demonstration of the *a priori* validity of the categories
> in respect of all objects of our senses, will the purpose of the
> deduction by fully attained. (B144-5)
> 



Here a perennial interpretive question arises: how should we construe
the argument we find in SS26, together with material from
SS24, which is sometimes designated as the second step of the
B-Deduction?



One position on this interpretive issue is advanced by Erich Adickes
(1889: 139-4) and H. G. Paton (1936, v. 1: 501), who argue that
while the material that precedes SS21 constitutes an
*objective* deduction, material in SS24 and SS26
comprise a *subjective* deduction. This distinction has its
source in the Preface to the A edition:



> 
> This enquiry, which is somewhat deeply grounded, has two sides. The
> one refers to the objects of pure understanding, and is intended to
> expound and render intelligible the objective validity of its *a
> priori* concepts. It is therefore essential to my purposes. The
> other seeks to investigate the pure understanding itself, its
> possibility and the cognitive faculties upon which it rests: and so
> deals with it in its subjective aspect. Although this latter
> exposition is of great importance for my chief purpose, it does not
> form an essential part of it. (Axvi-xvii)
> 



Henrich (1968-69) rejects the Adickes/Paton proposal for the
reason that in SS21 Kant states that the demonstration of the
validity of the categories is completed only in SS26, and the
passage from the A-Preface indicates that this is a task for the
objective deduction. In defense of Adickes and Paton, in SS20 Kant
claims to have established that the categories apply to the manifold
in any one given intuition, and affirms that he will now show that
categories apply to any object presented to the senses. In view of the
aim of the objective deduction, this move would seem to require only a
straightforward and trivial application of the result of SS20 to
any empirical intuition we might have (as many commentators have
noted). So, on a charitable interpretation of Kant's agenda,
showing that the categories apply to any object presented to the
senses plausibly involves considerations beyond the scope of the
objective deduction.



Henrich points out that although in the B-Deduction Kant sought to
avoid the problems of a subjective deduction, this "does not
mean that he neglected the demand for an explanation of the
possibility of relating the categories to intuitions." However,
by Kant's account, a subjective deduction features not only an
examination of cognitive faculties, but also an investigation of
"the possibility of the pure understanding," which would
include an investigation of how the categories are related to a priori
and to empirical intuition and to the objects presented to us in such
intuition. This is precisely the type of inquiry that we encounter in
SS24 and SS26 - and Henrich agrees. Thus it seems that
the views of Henrich, Paton, and Adickes can be reconciled: they
concur that the second step aims to show how it is that the categories
are related to objects of intuition and thus of experience in such a
way as to demonstrate that they correctly apply to them.



Anil Gomes (2010) proposes a more precise hypothesis for what is
missing in the first step that is addressed by the second step. Gomes
first appeals to a problem James van Cleve (1999) raises for the
Transcendental Deduction. Even if Kant succeeds in showing that
synthesis involves judging, and that judging involves the application
of the categories.



> 
> this would not be enough for his purposes. For that result in
> conjunction with the rest of the Transcendental Deduction would yield
> no conclusion stronger than this: all my representations are connected
> in judgements that use Kant's categories. But Kant wants to show
> that the categories are objectively valid - that they actually
> apply to objects of experience. (van Cleve 1999: 89)
> 



Kant hasn't established, according to van Cleve, that the
categories actually apply to experience. As Gomes (2010: 121) puts it,
"perhaps our application of the categories in experience is
always mistaken, and there is nothing which corresponds to the way in
which we have synthesized the manifold." As he points out, the
second step reaches its conclusion through the analysis of the
structure of our representation of space and time, from which Kant
then draws the conclusion that space and time themselves feature that
structure (Gomes 2010: 130; he cites a similar claim by Longuenesse
1998, 213). If space and time do feature the structure of our
representations of them, then the requisite correspondence is in
place, and van Cleve's objection is answered.



This is a contending and plausible hypothesis for a role for the
second step in the B-Deduction. One might ask, however, whether the
account Kant provides can respond convincingly to van Cleve's
objection. Even on certain idealist views, such as Leibniz's and
Kant's according to Robert Adams (1983, 1994: 217-61, cf. Wilson
1987), our ordinary sensible representations of space, and of physical
entities more generally, may not represent them as they really are. By
contrast, on Berkeley's idealist position as represented in the
third of the *Three Dialogues between Hylas and Philonous*
(Berkeley 1713/1998), the properties of physical entities match our
sensible representations of them exactly, without a possibility of a
mismatch; the oar in the water really is bent when I see it as bent.
On the type of idealism Kant endorses (and one might of course
question whether it has been established), the possibility of a
mismatch remains in place even if our representation of space
structures space itself (Pereboom 1988; Stang 2018; Jauernig 2021).
For instance, we may sensibly represent space as Euclidean while is in
fact Riemannian. One might respond that the representation that
structures space would then also be Riemannian, and we would have a
match. But then a crucial feature of our representation of space would
be inaccessible absent serious empirical investigation, and the nature
of the project would be altered.



The core text that divides interpretations of the second step is the
note to B160-1:



> 
> Space, represented as object (as is really required in geometry),
> contains more than the mere form of intuition, namely the
> comprehension of the manifold given in accordance with the form of
> sensibility in an intuitive representation, so that the form of
> intuition merely gives the manifold, but the formal intuition gives
> the unity of the representation. In the Aesthetic I ascribed this
> unity merely to sensibility, only in order to note that it precedes
> all concepts, though to be sure it presupposes a synthesis, which does
> not belong to the senses but through which all concepts of space and
> time first become possible. For since through it (as the understanding
> determines the sensibility) space or time are first given as
> intuitions, the unity of this a priori intuition belongs to space and
> time, and not to the concepts of the understanding (SS24).
> 



It's widely agreed that a crucial feature of the second step is
the claim that our intuitions of space and time are constituted in
such a way as to necessitate the unification of the manifold of
appearance by the application of the categories. In the Transcendental
Aesthetic, Kant aimed to show that space and time are forms of our
sensible intuition, and that for us appearances can only occur in
accord with these forms. But now, in the note to B160-1, Kant draws
our attention to the fact that space and time are not only forms of
intuition, but are intuitions themselves, and that they are intuitions
that feature unity. What's more, Kant specifies that this unity
'precedes all concepts, though to be sure it presupposes a
synthesis, which does not belong to the senses but through which all
concepts of space and time first become possible.' By the
synthesis that is presupposed 'the understanding determines the
sensibility.' So the unity of space and time is to be explained
with reference to the effect of the understanding upon sensibility
itself (Longuenesse 1998: 211-33; Keller 1998: 88-94;
Dickerson 2004: 196-201; Pollok 2008; Vinci 2014: 197-229;
Onof and Schulting 2015; Allison 2015: 374-432; Rosefeldt 2022).



The text, and in particular the B160-1 note, gives rise to a number of
interpretive issues for Kant's overall position. One is whether
here Kant countenances a kind of unity in our representations that is
not a result of categorical synthesis, but is instead is independent
of the categories. Hermann Cohen (1871/1987, 1907) and Eric Dufour
(2003) are strict categorical conceptualists about any such unity,
while Martin Heidegger (1929/1997) argues that there is a unity that
is accounted for by the productive imagination independently of the
categories; (Lorne Falkenstein 1995, Michel Fichant 1997, Robert Hanna
2008, 2011, Stephanie Grune 2011, Dennis Schulting 2012b, James
Messina 2014, Colin McLear 2015, and Jessica Wilson 2018 also defend
nonconceptualist positions on this score; see McLear 2014, 2020 for
overviews). Longuenesse (1998) contends that unity-yielding synthesis
is always a function of the understanding, but that there is a kind of
synthesis of the understanding that does not involve the categories,
while it yet anticipates them. Messina (2014), McLear (2015), Onof and
Schulting (2015), and Wilson (2018) argue that there are multiple
kinds of unity for Kant, and while some require categorical synthesis,
others do not. In particular, they maintain that space as intuited by
us has a unity that Onof and Schulting (2015) call unicity, which
consists of its singularity, its infinity, and its mereological
inversion, i.e., a metaphysical structure involving parts
ontologically depending on the whole, by contrast with the whole
ontologically depending on parts, as is the case for material objects
generally (here see Desmond Hogan 2021). Intuitive awareness of space
as featuring unicity does not, on their account, require categorical
synthesis.



As Tobias Rosefeldt (2022) points out, a longstanding puzzle for the
B160-1 note is that it references a notion of synthesis that precedes
all concepts, while the notion of synthesis to which Kant appeals in
the preceding sections of the B-Deduction is one that does employ
concepts, i.e., the categories, and thus does not precede concepts.
Commentators generally agree that this synthesis that precedes all
concepts must be subject to the unity of apperception (e.g., Messina
2014, Williams 2018), but how might it be more thoroughly
characterized? Rosefeldt proposes an account of the second step that
at this point features the notion of a decomposing synthesis, which
contrasts with a composing synthesis. Kant, as he points out,
introduces the notion of a decomposing synthesis only in the Second
Antinomy (A505/B533, A524/B552), but in Rosefeldt's view this
notion is aptly suited for Kant's objectives for the second
step. While a compositional synthesis constructs a whole from given
parts,a decomposing synthesis begins with a given whole and then
decomposes it in some way into parts. In this context, it decomposes
space as we are intuitively aware of it into one or more of its finite
parts, such as spheres or cubes, while the remaining infinite spatial
region excluded by those parts is represented as their phenomenal
background or horizon (cf., Husserl 1913, 1939). 



A test for this proposal is how a decomposing synthesis might
represent space given that we conceptualize it as infinite. On
Rosefeldt's account, the decomposition into finite parts may
involve imaginatively drawing line segments that form a square. We can
subsequently extend these lines in the imagination, and we are
conscious that we can freely vary the lines so that "however
large the finite space that we construct by drawing lines is, this
space will always only be phenomenally present to us within the
horizon of a still larger unlimited space." This does not amount
to intuiting space as infinite, but rather coming to understand that
the space we intuit is infinite by a *progressus ad infinitum*
(A510-11/B538-39), a progression of a series that we understand is
never complete (Onof and Schulting 2015). Accordingly, space itself,
in this way given as infinite, is an object of intuition for us as the
phenomenal horizon of finite regions of space from which we
distinguish it in the decomposing synthesis. A parallel account holds
for time. This account supplies the meaning, Rosefeldt argues, of
Kant's claim that "a synthesis which does not belong to
the senses" is required for "space and time [to be] first
given to us as intuitions" (B160-1n).



As Rosefeldt notes, the conclusion of the second step, the
applicability of the categories to space and time, requires appeal to
a composing synthesis, since the decomposing synthesis precedes all
concepts, and only in the composing synthesis are the categories
invoked. Thus a transition from the decomposing to a composing
synthesis must be made. One possible strategy is to claim that a
composing synthesis is not required for our representation of space as
whole, but only for our representations of determinate parts of space,
as when we construct figures in geometry. But while the text of the
B160-1 note does reference geometry, it also suggests (in the final
sentence) that a composing synthesis is required for our
representation of space as a whole. Onof and Schulting (2015) argue
that it is our explicit representation of the unicity of space as a
whole that requires synthesis in accord with the categories, and they
embellish their account by specifying precisely which categories are
required for the various aspects of unicity (Allison 2015: 420-30
provides a complementary account). An alternative, suggested by
Rosefeldt (2022), is that first of all, the finite spatial parts that
we actually distinguish in decomposing synthesis, either of individual
spatial parts or of various such parts taken as a group, feature a
unity, representation of which must be accounted for by compositional
synthesis. But further, we are conscious of the fact that the infinite
space revealed as the phenomenal horizon in the decomposing synthesis
can be subdivided infinitely into finite spatial parts, all of which
are represented as parts of that one all-encompassing infinite space.
Our representation of the unity of all of this, which Rosefeldt calls
world-unity, must also be accounted for by a composing synthesis. From
this we can see that given that a composing synthesis accounts for the
represented unity of the actual finite spaces we distinguish, it can
account for the represented world-unity as well. (For a discussion on
how a composing synthesis can operate on a target that is
indeterminate in the way that world-unity is, see Daniel Sutherland
2021, ch. 5, referenced in Rosefeldt 2022: 16 n.5).



Since it has already been shown that composing syntheses generally
must feature the categories, the claim is that we can infer that the
categories structure our representation of space, and by parallel
argument, our representation of time, and, moreover (in accord with
Kant's idealism), that they structure space and time themselves,
together with the spatial and temporal features of objects in space
and time. This allows us to see that the categories correctly apply to
objects in space and time, and to see that they do so from how they
structure our representations of space and time, and space and time
themselves. This would secure the generally agreed-upon objective of
the second step: to show how it is that the categories are related to
objects of intuition and thus of experience in such a way as to
demonstrate that they correctly apply to them.


## 2. The Refutation of Idealism



In the transcendental argument of the Refutation of Idealism,
Kant's target is not Humean skepticism about the applicability
of *a priori* concepts, but rather Cartesian skepticism about
the external world. This argument was added by Kant to the second
edition of the *Critique of Pure Reason* (B274-279, with
a change suggested in the Preface to B, Bxxxix-Bxli), and
subsequently embellished and reworked in a series of Reflections
(Guyer 1987: 279-316). More specifically, Kant intends to refute
what he calls problematic idealism, according to which the existence
of objects outside us in space is "doubtful and
indemonstrable" (B274). His strategy is to derive the claim that
such objects exist from my awareness that my representations have a
specific temporal order. At the present time I am aware of the
specific temporal order of many of my past experiences, an awareness
produced by memory. But what is it about what I remember that allows
me to determine the temporal order of my experiences? There must be
something by reference to which I can correlate the remembered
experiences that allows me to determine their temporal order. But
first, I have no conscious states that can play this role. Further,
this reference cannot be time itself, for "time by itself is not
perceived;" Kant argues for this claim in the First Analogy
(B224-5). As Guyer puts it, it is not as if the content of
memories of individual events are manifestly indexed to specific
times, as sportscasts and videotapes often are (Guyer 1987: 244). Kant
contends that the only other candidate for this reference is something
outside of me in space, and it must be something (relatively)
permanent (cf. First Analogy, B224-5). Perhaps this claim is
made plausible by how we often actually determine the times at which
our experiences occur. We use observations of sun's positions,
or of a clock that indicates time by way of the period of a pendulum,
or by the period of the vibration of a cesium atom. Kant's
argument can be seen as exploiting this fact, together with the
observation that there is no similar periodic process in human
conscious experience considered independently of any spatial objects
it might represent, and that we lack any awareness of time by itself,
to show we must perceive objects outside us in space by reference to
which we can determine the temporal order of our past experiences.



George Dicker provides a compelling initial representation of
Kant's argument (Dicker 2004, 2008):


1. I am conscious of my own existence in time; that is, I am aware,
and can be aware, that I have experiences that occur in a specific
temporal order. (premise)
2. I can be aware of having experiences that occur in a specific
temporal order only if I perceive something permanent by reference to
which I can determine their temporal order. (premise)
3. No conscious state of my own can serve as the permanent entity by
reference to which I can determine the temporal order of my
experiences. (premise)
4. Time itself cannot serve as this permanent entity by reference to
which I can determine the temporal order of my experiences.
(premise)
5. If (2), (3), and (4), are true, then I can be aware of having
experiences that occur in a specific temporal order only if I perceive
persisting objects in space outside me by reference to which I can
determine the temporal order of my experiences. (premise)
6. Therefore, I perceive persisting objects in space outside me by
reference to which I can determine the temporal order of my
experiences. (1-5)



Several points of interpretation should be noted. First, it is
generally agreed that the notion of awareness in Premise (1) should be
interpreted as a success notion, i.e., that to be aware that I have
experiences that occur in a specific temporal order is to correctly
determine that they occur in this order (Allison 1983: 290ff, Guyer
1987: 293ff, Dicker 2004, 195ff., 2008; Chignell 2010). Second, most
commentators concur that the experiences at issue are my past
experiences. Guyer suggests that the argument might be extended to
combinations of my past and my present experience, but Dicker objects
that the fact that past experiences occurred before the present one is
directly knowable by introspection, and so doesn't require the
external reference (Guyer 1987; Dicker 2004: 195ff.). Third, Jonathan
Bennett points out that we have single memories whose content spans an
appreciable length of time that allow us to determine the order of
past mental states . When one remembers hearing a certain word, one
can accurately determine by the content of a single memory that
certain phoneme-experiences occurred prior to other
phoneme-experiences - for example, that one heard
'mad' and not 'dam' (Bennett 1966:
228-9). Dicker (2004: 201-2) remarks that we may be able
to determine accurately the order some of our past states by means of
such memories, but we cannot ascertain the order of most of our past
experiences in this way. He therefore advocates a restriction of the
argument to the experiences we can correctly order but not in the way
Bennett adduces. Fourth, many commentators have noted that we might
have perceived time directly. Guyer, as we just saw, suggests that all
of our conscious experiences might have featured a time clock, much
like a television sportscast or a video camera (1987: 244; cf.
Strawson 1966). But as Dicker points out, in actual fact our
experience does not have any such feature, and he is content for
Premise (4), that time itself cannot serve as the reference whereby I
correctly determine the temporal order of my past experiences, to
state a merely contingent fact about us (2004, 2008). Chignell (2010)
expresses a concern about interpretations of the Refutation in which
it is merely a contingent fact about us that the alternative methods
for determining the temporal order of my past experiences are
unavailable, for then the conclusion, that we perceive objects in
space, would inherit such mere contingency, which he argues to be at
odds with Kant's hopes for the Refutation. Fifth, commentators
differ on the relation that must obtain between the objects in space
and the experiences whose temporal order we can correctly determine.
Guyer argues that the relation must be causal, since "the states
of the self are judged to have a unique order just insofar as they are
judged to be caused... by the successive states of enduring
objects" (Guyer 1987: 309; cf. Dicker 2004: 200, 2008). By
contrast, in Allison's view we require the temporal order of
objects in space only as a backdrop against which to determine the
temporal order of our experiences; "an enduring, perceivable
object (or objects) is required to provide a frame of reference by
means of which the succession, coexistence, and duration of
appearances in a common time can be determined" (Allison 1983:
201). If the object in space that provides the reference is the sun,
for example, the states of the sun don't need to cause my
experiences for me to determine their temporal order by means of those
states.



Three of the most pressing problems that have been raised for the
Refutation are the following. First, a skeptic might well reject
Premise (1) on the ground of a general skepticism about memory
(Allison 1983: 306-7). Bertrand Russell, for example, suggests
that for all I know I was born five minutes ago (Russell 1912). On
this skeptical hypothesis, I would be mistaken in my belief that I had
experiences A, B, and C which occurred more than five minutes ago,
first A, then B, and lastly C. Plausibly, a skeptic who claimed that
we lack adequate justification for a belief that external objects
exist would likely also be disposed to claim that I lack justification
for my belief that I had experiences that occurred in the past in that
specific temporal order. Thus Kant's supposition that Premise
(1) yields leverage against an external-world skeptic is mistaken (cf.
Dicker 2008, Chignell 2010).



Second, consider the claim that my mental states (or the mental
subject itself) are as suited as objects in space to function as a
reference whereby I can correctly judge the temporal order of my past
experiences. Suppose I had available as such a reference only the mere
mental appearance of a digital clock in one corner of my field of
consciousness. This would not clearly be less effective than an actual
clock in space. To this one might reply, with Dicker, that there are
no actual mental states that are adequate to serve as such a
reference. However, and this is the deeper worry, on Berkeley's
idealist view according to which the *esse* (to be) of objects
in space is their *percipi* (to be perceived), any spatial
objects would be nothing more than mental states of some subject, or
aspects of those states, but Berkeleyan spatial perceptions would be
as adequate a reference by which to determine the temporal order of my
past experiences as perceptions of spatial objects that are in some
sense distinct from my mental states (cf. Allison 1983: 300-1;
Vogel 1993; Chignell 2010).



Third, one might contend that Kant's Refutation demonstrates
that the reference in question must be (relatively) permanent, and
that there is nothing in the Berkeleyan spatial realm that satisfies
this requirement. However, to this one might respond that the
reference by which I determine the temporal order of my past
experiences need not be permanent in a way that cannot be satisfied by
Berkeleyan spatial objects. If in the corner of my field of
consciousness featured distinct momentary flashes, every second,
indicating the date and time to the second, I would be able to
determine the temporal order of my past experiences by their means
(cf., van Cleve, reported in Dicker 2004: 207).



A note on the second of these concerns: Several commentators have
argued that Kant's Refutation of Idealism is meant to undermine
any metaphysical sort of idealism, including metaphysical idealisms
that have been attributed to Kant (Guyer 1987: 317-29). But
while this reading has interesting support, one should hesitate to
endorse it solely on the ground that Kant maintains that spatial
objects are distinct from the states of the perceiver. On a plausible
metaphysical interpretation of Kant's idealism, the
*esse* of objects in space is not their *percipi*, since
Kant's spatial objects, by contrast with Berkeley's, are
recognition-transcendent. In Berkeley's position, a
subject's perception of an oar in the water as crooked is not a
misperception, for "what he immediately perceives by sight is
not in error, and so far he is in the right," and it is
misleading only because it is apt to give rise to mistaken inferences
(Berkeley 1713: Third Dialogue); while for Kant this perception is in
error. In Kant's view, the oar is recognition-transcendent by
virtue of the Second Postulate's provision that the actuality of
such objects is determined causally:



> 
> That which is bound up with the material conditions of experience,
> that is, with sensation, is actual (*wirklich*). (A218=B266)
> 



The actual is that which conforms to the system of empirical causal
laws (A225/B272ff.), and because the crookedness of the oar does not
so conform, it is not actual. How the Second Postulate rules out the
existence of the apparent spatial objects of dreams and hallucinations
is spelled out in the third note to the Refutation of Idealism:



> 
> Note 3. From the fact that the existence of outer things is required
> for the possibility of a determinate consciousness of the self, it
> does not follow that every intuitive representation of outer things
> involves the existence of those things, for their representation can
> very well be the product merely of the imagination (as in dreams and
> delusions). Such representation is merely the product of previous
> outer perceptions, which, as has been shown, are possible only through
> the reality of outer objects... Whether this or that supposed
> experience be not purely imaginary, must be ascertained from its
> special determinations, and through its congruence with the criteria
> of all actual experience (*wirklichen Erfahrung*).
> (B278-9 cf.A376, cf. A492=B520-1)
> 



The objects of dreams and hallucinations don't meet the
criterion of actuality of the Second Postulate, that is, according
with the laws of causality. Thus while in Berkeley's view the
*esse* of spatial things consists in their being perceived by
the senses, for Kant they are the objects of the correct
causal/scientific account of the contents of our outer experience.
This causal criterion allows that a spatial object, or, more
precisely, the matter from which it is constituted, is (at least
relatively) permanent - which would seem ruled out in
Berkeley's position, since the spatial object does not last any
longer than the idea does. (Berkeley does say that the ideas of what
"are called real things" differ from "those excited
in the imagination" by "being less regular, vivid, and
constant" (Berkeley 1710, *Principles* Part I, 33), but
for him this difference does not challenge or undermine the claim that
the *esse* of a physical object is its *percipi*.) None
of this forces a metaphysical realist as opposed to an idealist
reading of Kant.



Yet at the same time, according to the second concern, the Refutation
is inadequate even if its ambition is restricted to demonstrating the
existence of merely metaphysically ideal but nonetheless
recognition-transcendent objects outside us in space. For granting
that the Refutation establishes that for me to determine the temporal
order of my past experiences I must perceive objects in space, it
fails to show that I need to perceive spatial objects any more
realistic than the Berkeleyan ones. More generally, the worry is that
Berkeleyan version of idealism has the resources to yield as adequate
a reference for me to determine the temporal order of my past
experiences as any rival position Kant is plausibly interpreted as
endorsing, and that for this reason the Refutation falls short of its
aim.


## 3. Contemporary World-Directed Transcendental Arguments



Kant-inspired transcendental arguments against skepticism about the
external world were developed with vigor in the mid-twentieth century,
notably by P. F. Strawson, most famously in his Kantian reflections in
*The Bounds of Sense* (1966). These arguments are often
reinterpretations of, or at least inspired by, Kant's
Transcendental Deduction and his Refutation of Idealism. Some are more
ambitious than Kant's would seem to be, insofar as they attempt
to refute some variety of skepticism by showing that there is an
essential commitment of the skeptical position for which the falsity
of that position is a necessary condition (Nagel 1997: 60ff.).
Strawson's most famous transcendental argument (1966:
97-104) is modeled on the Transcendental Deduction, but
explicitly without a commitment to synthesis or any other aspect of
Kant's transcendental psychology. His target is a purely
sense-datum experience, which does not feature objects,
"conceived of as distinct from any particular states of
awareness of them," that is, a Berkeleyan experience of spatial
objects whose *esse* is *percipi* (1966: 98). The core
of the argument is as follows. From the premise that every (human)
experience is such that it is possible for its subject to become aware
of it and ascribe it to herself, we can infer that in every experience
the subject must be capable of distinguishing a recognitional
component not wholly absorbed by, and thus distinct from, the item
recognized (1966: 100). From this we can infer that the subject must
conceptualize her experiences in such a way so as to contain the basis
for a distinction between a subjective component - how the
experienced item seems to the subject, and an objective component
- how the item actually is. Strawson specifies that
"collectively," this comes to "the distinction
between the subjective order and arrangement of a series of such
experiences on the one hand, and the objective order and arrangement
of the items of which they are the experiences on the other"
(1966: 101). Conceptualizing experience as involving an objective
order and arrangement of items amounts to making objectively valid
judgments about it, which, in turn, implies that experience must
consist of a rule-governed connectedness of representations (1966:
98). Summarizing, from a premise about self-consciousness, we can
infer that the subject must conceptualize her experience so as to
feature a distinction between "the subjective route of his
experience and the objective world through which it is a route,"
where the experience of the objective world consists in a
rule-governed order of representations (1966: 105).



Barry Stroud, in his 1968 article "Transcendental
Arguments," issued a formidable challenge to the enterprise of
defeating the external-world skeptic by transcendental arguments of
this sort (Stroud 1968). There Stroud contends that such
transcendental arguments are undermined by a problem which can be
stated quite generally. These arguments feature reasoning from some
aspect of experience or knowledge to the claim that the contested
feature of the external world in fact exists. In each case the
*existence* of the external feature will not be a necessary
condition of the aspect of experience or knowledge in question, for a
*belief* about the external feature would always suffice.
Although the claim about existence of the aspect of the external world
could be secured if certain kinds of verificationism or idealism were
presupposed, these views are highly controversial. Besides, one could
make as much of an inroad against the skeptic armed with the
verificationism or idealism alone, without adducing the transcendental
argument at all (cf. Brueckner 1983, 1984).



Although Strawson's transcendental argument in *The Bounds of
Sense* is not a specific target in Stroud's (1968), Anthony
Brueckner suggests that it is susceptible to the line of criticism
that Stroud develops (Brueckner 1983: 557-8). For, arguably,
Strawson can only conclude that experience must be conceptualized in a
certain way, such as to allow the subject to make the distinction
between an objective world and her subjective path through it. This is
not a conclusion about how a mind-independent world must be, but only
about how it must be thought. (Alternatively, Strawson might be read
as drawing only a conclusion about how experience must be
conceptualized, which would render the transcendental argument as one
of a more modest variety (see below)).



Recent developments of transcendental arguments reflect a struggle to
accommodate Stroud's criticism, and often chastened expectations
about what such arguments might establish by way of refuting
skepticism. One more modest sort of transcendental argument begins
with a premise about experience or knowledge that is acceptable to the
skeptic in question, and then proceeds not to the existence of some
aspect of the external world, but in accord with Stroud's
criticism, to a belief in the existence of some aspect of the external
world. Stroud himself advocates a strategy of this sort (Stroud 1994,
1999), as does Robert Stern (1999). The kind proposed by Stroud begins
with the premise that we think of the world as being independent of
us, and it concludes, as a necessary condition of this premise, that
we must think of it as containing enduring particulars. Such an
argument does not claim that as a necessary condition of this premise
there must exist such particulars. It contends only for "a
connection solely within our thought: if we think in certain ways, we
must think in certain other ways" (Stern 1999: 165). A belief or
thought to which one reasons in this way would, in Stroud's
conception, have a certain *indispensability*, "because
no belief that must be present in any conception or any set of beliefs
about an independent world could be abandoned consistently with our
conception of the world at all," and it would be
*invulnerable* "in the special sense that it could not be
found to be false consistently with its being found to be held by
people" (Stern 1999: 166).



Stern advances a conception of this kind of argument on which it
addresses a skeptic who questions whether certain beliefs cohere with
others in one's set, as opposed to a skeptic who questions
whether certain beliefs are true (Stern 1999). A modest transcendental
argument would then aim to show that a belief whose coherence with the
other beliefs is challenged so coheres after all. The requisite
coherence might be demonstrated by showing that the belief in question
is actually a necessary condition of a belief that is indispensable
(in some coherentist sense) to one's set. Mark Sacks (1999)
objects that if at the same time one were to admit that the belief
might not be true, one's sense that one is justified in holding
the belief would be undermined. This worry is a serious one. Sacks
argues that it arises because of a tension between the coherentist
theory of justification and the realist correspondence theory of truth
that the external world skeptic presupposes. One might respond, he
points out, by accepting a coherence theory of truth as well, but this
would be to adopt a version of idealism. Moreover, it seems that
Sacks's proposal would not solve the problem, for the reason
that even if one accepted a coherence theory of truth, one would still
have to admit that for specific instances of a belief one might be
mistaken, even if one maintained that one was justified in holding
that belief on grounds of coherence.



An important criticism of Stroud's proposed sort of modest
transcendental argument is raised by Brueckner (1996). Brueckner
addresses the fit between the claim that certain non-skeptical beliefs
are invulnerable in Stroud's sense, and the admission that they
might not be true. More precisely, he challenges the claim that one
can simultaneously affirm the following two principles, each gleaned
from Stroud (1994):



> 
> (CT) If we attribute beliefs to speakers (if we believe that they have
> beliefs with determinate contents), then we must also believe that
> there is an independent world of enduring objects with which they
> interact.
> 



and



> 
> (SK) Although we believe many things about a world independent of us
> and our experiences, ... none of those beliefs is true.
> 



Brueckner divides (SK) into


1. we believe many things about an external reality independent of us
and our experiences



and


2. none of these beliefs is true.



Stroud argues, in effect, that given CT we cannot believe that (i) and
(ii) are true, but nonetheless, we can believe that (i) and (ii) are
logically compossible given CT. Brueckner argues that using similar
reasoning, given CT we cannot conceive of a possible world in which
both (i) and (ii) hold, and this fact undermines Stroud's claim.
To conceive of a world W in which (i) is true is to conceive of a
world in which we (in the actual world) attribute beliefs about
mind-independent objects to counterfactual versions of us (CVs) in W.
But given CT, we must now also conceive of W as featuring
mind-independent objects with which these CVs interact. Consider the
CVs' belief *that there exist mind-independent objects*
- a belief they share with us. This belief of theirs will be
true. And thus in W (ii) will be false. Hence we have not conceived of
a world in which given CT, SK is nevertheless true, and indeed, we
will not be able to conceive of such a world. But our not being able
to conceive of a possible world in which given CT, SK is true,
constitutes strong evidence against the claim that SK is logically
possible given CT (1996: 274-75). Brueckner does not think that
this argument demonstrates that it is inconsistent to accept CT and
assert that SK is logically possible, but that there will be no
evidence of the usual kind for this claim - evidence from
conceivability. Thus given the transcendental argument he advances,
Stroud will be pushed in the direction of the immodest conclusion that
it is not possible for us to be mistaken in our belief that there
exist mind-independent objects.



From this one might be tempted to conclude that despite his critique
of 1968, Stroud, with Brueckner's assistance, has found a
transcendental argument that does in fact establish a conclusion about
the external world. However, so far nothing has been said to turn back
Stroud's 1968 critique, and it seems much more likely that the
argument Stroud now advances can at best conclude with a version of CT
in which the term "independent" must be read in a
transcendentally ideal sense - in which, for example, the nature
of certain physical objects is determined by our best scientific
theories about them, and our sensory experiences can be in error about
these objects. And if this is so, then the argument would secure a
belief about the external world only on the presupposition of
metaphysical idealism, and this is one of the ways in which
anti-skeptical transcendental arguments might be doomed according to
Stroud's 1968 critique.



Despite these sorts of challenges, the aspiration to forge
transcendental arguments with considerable anti-skeptical force has
not waned. Qassim Cassam (1999), Sacks (2000), and Stern (2000), for
example, have developed creative and nuanced versions of
transcendental arguments designed to negotiate the type of problem
Stroud has pressed.


## 4. Contemporary Practical Transcendental Arguments



Kant ethical writings (1785, 1788) feature several widely and
intensely discussed transcendental arguments (see the entry
 Kant's moral philosophy).
 As in metaphysics and epistemology, in recent times anti-skeptical
transcendental arguments have also been developed in the practical
sphere.



One of P. F. Strawson's most influential works is his essay on
moral responsibility, "Freedom and Resentment" (Strawson
1962). The reasoning in this article has not traditionally been
interpreted as a transcendental argument, but recently Justin Coates
has made a strong case for such a reading (Coates 2016; cf. Pereboom
2016). In Coates's account, the argument begins with the premise
to which the moral responsibility skeptic would agree, that meaningful
adult interpersonal relationships are possible for us. It continues by
pointing out that relationships of this sort require that the
participants show each other good will and respect, and that they be
justified in expecting this of one another. Expectations for good will
and respect in turn require susceptibility to the reactive attitudes,
such as moral resentment, indignation, and gratitude, and in
particular, justified expectations for good will and respect
presuppose that the participants are apt recipients of these reactive
attitudes. But to be an apt target of the reactive attitudes is just
what it is to be a morally responsible agent. Consequently, that we
are morally responsible agents is a necessary condition of the
possibility for us of meaningful adult interpersonal
relationships.



Note that not all the connections among the steps of the argument are
plausibly instances of appeals to logical or even metaphysical
necessary conditions. True, some are: if being an apt target of the
reactive attitudes is what it is to be a morally responsible agent,
the necessary connection invoked would be conceptual or metaphysical.
But if expectations for good will and respect do require
susceptibility to the reactive attitudes, this would be plausibly a
case of nomological necessitation, where the relevant laws are
psychological. But given the sort of skepticism targeted, nomological
necessitation is not too weak a connection; it is not called into
question by the arguments of the moral responsibility skeptic.



Critics have in effect taken issue with a number of steps of this
argument, for example that expectations for good will and respect
require susceptibility to the reactive attitudes, and that justified
expectations for good will and respect presuppose that the
participants are apt recipients of the reactive attitudes. Perhaps
human relationships do not require susceptibility to moral resentment
and indignation, but only to the nonreactive attitudes of moral
protest, disappointment, and sorrow (Pereboom 2022). Another avenue of
criticism involves separating moral responsibility from being an apt
target of the reactive attitudes. It may be that a forward-looking,
that is, what Strawson calls an 'optimistic' notion of
responsibility, is all that's required for good relationships,
and it is not characterized by being an apt target of the reactive
attitudes. But these criticisms are controversial, and
Strawson's argument is widely accepted and acclaimed.



Another prominent transcendental argument in the practical sphere is
the sort Christine Korsgaard (1996) develops for Kantian claim that we
must value ourselves as rational agents. Here is Robert Stern's
(2017) representation of one argument of this sort. The initial
premise concerns rational choice, and crucially features the notion of
an agent's practical identity, the distinctive nature of a
person as an agent, which may include, for example, being a parent or
a philosophy professor:


1. To rationally choose to do X, you must take it that doing X is the
rational thing to do.
2. Since there is no reason in itself to do X, you can take it that X
is the rational thing to do only if you regard your practical identity
as making X the rational thing to do.
3. You cannot regard your practical identity as making doing X the
rational thing to do unless you can see some value in that practical
identity.
4. You cannot see any value in any particular practical identity as
such, but can regard it as valuable only because of the contribution
it makes to giving you reasons and values by which to live.
5. You cannot see having a practical identity as valuable in this way
unless you think your having a life containing reasons and values is
important.
6. You cannot regard it as important that your life contain reasons
and values unless you regard your leading a rationally structured life
as valuable.
7. You cannot regard your leading a rationally structured life as
valuable unless you value yourself qua rational agent.
8. Therefore, you must value yourself qua rational agent, if you are
to make any rational choice.



Stern (2017) explains this argument as follows. To act is to do or
choose something for a reason. However, an agent has reasons to act
only because of her practical identity; she does not have reasons to
act independently of that identity. But a practical identity can yield
such a reason only if she regards that identity as valuable. Merely
being a parent gives one no reason to care for one's children.
Rather, valuing one's parenthood has this force. At the same
time, an agent cannot regard a particular practical identity as
valuable in itself; Korsgaard argues that this sort of realism about
value is implausible. The only remaining explanation is that she
regards it as valuable because of the contribution it makes to
providing her with reasons and values by which to live. But then she
must believe that it matters that her life has the sort of rational
structure that having such identities provides. However, to see that
as mattering, she must regard leading a rationally structured life as
valuable. Then, in conclusion, to regard leading such a life as
valuable, an agent must see her rational nature as valuable.


## 5. Concluding Remarks



The legacy of the arguments such as the Transcendental Deduction and
the Refutation of Idealism includes not only Kant's actual
successes, but also a number of influential philosophical strategies:
the now-standard tactic of arguing for concepts whose source is in the
mind from universal and necessary features of experience; the idea of
drawing significant philosophical conclusions from premises about
self-consciousness alone; and the notion of a transcendental argument,
which from an uncontroversial premise about our thought, knowledge or
experience, reasons to a substantive and unobvious presupposition and
necessary condition of this claim.