## 1. Kinds of Consciousness



One of the advances made in the last few decades has been to
distinguish between different questions concerning consciousness (see
particularly: Rosenthal 1986; Dretske 1993; Block 1995; Lycan 1996).
Not everyone agrees on quite *which* distinctions need to be
drawn. But all are agreed that we should distinguish *creature*
consciousness from *mental-state* consciousness. It is one
thing to say *of an individual person or organism* that it is
conscious (either in general or of something in particular); and it is
quite another thing to say *of one of the mental states* of a
creature that it is conscious.



It is also agreed that within creature-consciousness itself we should
distinguish between *intransitive* and *transitive*
variants. To say of an organism that it is conscious
*simpliciter* (intransitive) is to say just that it is awake,
as opposed to asleep or comatose. There don't appear to be any
deep philosophical difficulties lurking here (or at least, they
aren't difficulties specific to the topic of consciousness, as
opposed to mentality in general). But to say of an organism that it is
conscious *of such-and-such* (transitive) is normally to say at
least that it is *perceiving* such-and-such, or *aware
of* such-and-such. So we say of the mouse that it is conscious of
the cat outside its hole, in explaining why it doesn't come out;
meaning that it *perceives* the cat's presence. To
provide an account of transitive creature-consciousness would thus be
to attempt a theory of perception.



There is a choice to be made concerning transitive
creature-consciousness, failure to notice which may be a potential
source of confusion. For we have to decide whether the perceptual
state in virtue of which an organism may be said to be
transitively-conscious of something must itself be a conscious one
(state-conscious--see below). If we say 'Yes' then we
shall need to know more about the mouse than merely that it perceives
the cat if we are to be assured that it is conscious of the
cat--we shall need to establish that its percept of the cat is
itself conscious. If we say 'No', on the other hand, then
the mouse's perception of the cat will be sufficient for the mouse to
count as conscious of the cat; but we may have to say that although it
is conscious of the cat, the mental state in virtue of which it is so
conscious is not itself a conscious one! It may be best to by-pass any
danger of confusion here by avoiding the language of
transitive-creature-consciousness altogether. Nothing of importance
would be lost to us by doing this. 



Turning now to the notion of *mental-state consciousness*, the
major distinction here is between *phenomenal consciousness*,
on the one hand--which is a property of states that it is
*like something* to be in, that have a distinctive
'feel' (Nagel 1974)--and various
functionally-definable forms of *access consciousness*, on the
other (Block 1995). Most theorists believe that there are mental
states--such as occurrent thoughts or judgments--that are
access-conscious (in whatever is the correct functionally-definable
sense), but that are not phenomenally conscious. In contrast, there is
considerable dispute as to whether mental states can be
phenomenally-conscious without also being conscious in the
functionally-definable sense--and even more dispute about whether
phenomenal consciousness can be *reductively explained* in
functional and/or representational terms.



It is plain that there is nothing deeply problematic about
functionally-definable notions of mental-state consciousness, from a
naturalistic perspective. For mental functions and mental
representations are the staple fare of naturalistic accounts of the
mind. But this leaves plenty of room for dispute about the form that
the correct functional account should take. Some claim that for a
state to be conscious in the relevant sense is for it to be poised to
have an impact on the organism's decision-making processes (Kirk 1994;
Dretske 1995; Tye 1995, 2000), perhaps also with the additional requirement
that those processes should be distinctively *rational* ones
(Block 1995). Others think that the relevant requirement for
access-consciousness is that the state should be suitably related to
higher-order representations--experiences and/or thoughts--of
that very state (Armstrong 1968, 1984; Rosenthal 1986, 1993, 2005;
Dennett 1978a, 1991; Carruthers 1996, 2000, 2005; Lycan 1987,
1996; Gennaro 2012).



What *is* often thought to be naturalistically problematic, in
contrast, is phenomenal consciousness (Nagel 1974, 1984; Jackson 1982,
1986; McGinn 1991; Block 1995; Chalmers 1996). And what is really and
deeply controversial is whether phenomenal consciousness can be
*explained* in terms of some or other functionally-definable
notion. *Cognitive* (or *representational*) theories
maintain that it can. *Higher-order* cognitive theories
maintain that phenomenal consciousness can be reductively explained in
terms of representations (either experiences or thoughts) that are
higher-order. It is such theories that concern us here.


## 2. The Motivation for a Higher-Order Approach



Higher-order theories, like cognitive/representational theories in
general, assume that the right *level* at which to seek an
explanation of phenomenal consciousness is a cognitive one, providing
an explanation in terms of some combination of *causal role*
and *intentional content*. All such theories claim that
phenomenal consciousness consists in a certain kind of intentional or
representational content (*analog* or
'fine-grained' in comparison with any concepts we possess)
figuring in a certain distinctive position in the causal architecture
of the mind. They must therefore maintain that these latter sorts of
mental property don't already implicate or presuppose phenomenal
consciousness. In fact, all cognitive accounts are united in rejecting
the thesis that the very properties of *mind* or
*mentality* already presuppose phenomenal consciousness, as
proposed by Searle (1992, 1997) for example. The higher-order approach
does not attempt to reduce consciousness directly to neurophysiology
but rather its reduction is in mentalistic terms, that is, by using
such notions as thoughts and awareness.



The major divide amongst representational theories of phenomenal
consciousness in general, is between accounts that are provided in
purely first-order terms and those that implicate higher-order
representations of one sort or another (see below). These higher-order
theorists will allow that first-order accounts--of the sort
defended by Dretske (1995) and Tye (1995), for example--can
already make some progress with the problem of consciousness.
According to first-order views, phenomenal consciousness consists in
analog or fine-grained contents that are available to the first-order
processes that guide thought and action. So a phenomenally-conscious
percept of red, for example, consists in a state with the analog
content *red* which is tokened in such a way as to feed into
thoughts about red, or into actions that are in one way or another
guided by redness. Now, the point to note in favor of such an account
is that it can explain the natural temptation to think that phenomenal
consciousness is in some sense *ineffable*, or
*indescribable*. This will be because such states have
fine-grained contents that can slip through the mesh of any conceptual
net. We can always distinguish many more shades of red than we have
concepts for, or could describe in language (other than
indexically--e.g., '*That* shade').



The main motivation behind higher-order theories of consciousness, in
contrast, derives from the belief that all (or at least most)
mental-state types admit of both conscious and unconscious varieties.
Almost everyone now accepts, for example, (post-Freud) that beliefs
and desires can be activated unconsciously. (Think, here, of the way
in which problems can apparently become resolved during sleep, or
while one's attention is directed to other tasks. Notice, too, that
appeals to unconscious intentional states are now routine in cognitive
science.) And then if we ask what makes the difference between a
conscious and an unconscious mental state, one natural answer is that
conscious states are states that we are *aware of*. And if
*awareness* is thought to be a form of creature-consciousness
(see section 1 above), then this will translate into the view that
conscious states are *states of which the subject is aware*, or
states of which the subject is creature-conscious. That is to say,
these are states that are the objects of some sort of higher-order
representation--whether a higher-order perception or experience,
or a higher-order thought. This is similar to the widely referenced
Transitivity Principle (TP) which says that a conscious state is a
state whose subject is, in some way, aware of being in it. On the
other hand, a mental state of which a subject is
completely *un*aware is clearly an unconscious state. (See also
Lycan's (2001b)'related simple argument' for a
higher-order representation account of consciousness.)



One crucial question, then, is whether perceptual states as well as
intentional states admit of both conscious and unconscious varieties. Can there
be, for example, such a thing as an unconscious visual perceptual
state? Higher-order theorists are united in thinking that there can.
Armstrong (1968) uses the example of absent-minded driving to make the
point. Most of us at some time have had the rather unnerving
experience of 'coming to' after having been driving on
'automatic pilot' while our attention was directed
elsewhere--perhaps having been day-dreaming or engaged in intense
conversation with a passenger. We were apparently not consciously
aware of much of the route we have recently taken, nor of any of the
obstacles we avoided on the way. Yet we must surely have been
*seeing*, or we would have crashed the car. Others have used
the example of blindsight (Carruthers 1989, 1996). This is a condition
in which subjects have had a portion of their primary visual cortex
destroyed, and apparently become blind in a region of their visual
field as a result. But it has now been known for some time that if
subjects are asked to *guess* at the properties of their
'blind' field (e.g. whether it contains a horizontal or
vertical grating, or whether it contains an 'X' or an
'O'), they prove remarkably accurate. Subjects can also
reach out and grasp objects in their 'blind' field with
something like 80% or more of normal accuracy, and can catch a ball
thrown from their 'blind' side, all without conscious
awareness. (See Weiskrantz 1986, 1997, for details and
discussion.)



A powerful case for the existence of unconscious visual
experience has also been generated by the *two-systems theory* of
vision proposed and defended by Milner and Goodale (1995; see also
Jacob and Jeannerod 2003; Glover 2004). They review a wide variety of
kinds of neurological and neuro-psychological evidence for the
substantial independence of two distinct visual systems, instantiated
in the temporal and parietal lobes respectively. They conclude that
the parietal lobes provide a set of specialized semi-independent
modules for the on-line visual control of action; whereas the temporal
lobes are primarily concerned with more off-line functions such as
visual learning and object recognition. And only the perceptions
generated by the temporal-lobe system are phenomenally conscious, on
their account. (Note that this isn't the familiar distinction between *what*
and *where* visual systems, but is rather a successor to it.
For the temporal-lobe system is supposed to have access both to
property information and to spatial information. Instead, it is a
distinction between a combined *what-where* system located in
the temporal lobes and a *how-to* or action-guiding system
located in the parietal lobes.)



To get the flavor of Milner and Goodale's hypothesis, consider just
one strand from the wealth of evidence that they provide. This is a
neurological syndrome called *visual form agnosia*, which
results from damage localized to both temporal lobes, leaving primary
visual cortex and the parietal lobes intact. (Visual form agnosia is
normally caused by carbon monoxide poisoning, for reasons that are
little understood.) Such patients cannot recognize objects or shapes,
and may be capable of little conscious visual experience; but their
sensorimotor abilities remain largely intact.



One particular patient--D.F.--has now been examined in
considerable detail. While D.F. is severely agnosic, she isn't
completely lacking in conscious visual experience. Her capacities to
perceive colors and textures are almost completely preserved. (Why
just these sub-modules in her temporal cortex should have been spared
isn't known.) As a result, she can sometimes guess the identity of a
presented object--recognizing a banana, say, from its yellow
color and the distinctive texture of its surface. But she is unable to
perceive the shape of the banana (whether straight or curved, say);
nor its orientation (upright or horizontal; pointing towards her or
across). Yet many of her sensorimotor abilities are close to
normal--she would be able to reach out and grasp the banana,
orienting her hand and wrist appropriately for its position and
orientation, and using a normal and appropriate finger grip. Under
experimental conditions it turns out that although D.F. is at chance
when identifying the orientation of a broad line or letter-box, she is
almost normal when posting a letter through a similarly-shaped slot
oriented at random angles. In the same way, although she is at chance
when trying to discriminate between rectangular blocks of very
different sizes, her reaching and grasping behaviors when asked to
pick up such a block are virtually indistinguishable from those of
normal controls. It is very hard to make sense of these data without
supposing that the sensorimotor perceptual system is functionally and
anatomically distinct from the object-recognition/conscious
system.



But what implications does this have for phenomenal consciousness?
Must these unconscious percepts also be lacking in *phenomenal*
properties? Most people think so. While it may be possible to get
oneself to believe that the perceptions of the absent-minded car
driver can remain phenomenally conscious (perhaps lying outside of the
focus of attention, or being instantly forgotten), it is very hard to
believe that either blindsight percepts or D.F.'s sensorimotor
perceptual states might be phenomenally conscious ones. For these
perceptions are ones to which the subjects of those states are
*blind*, and of which they *cannot* be aware. And the
question, then, is what makes the relevant difference? What is it
about a conscious perception that renders it *phenomenal*, that
a blindsight perceptual state would correspondingly lack? Higher-order
theorists are united in thinking that the relevant difference consists
in the presence of something *higher-order* in the first case
that is absent in the second. The same would go for the difference
between unconscious and conscious desires, emotions, pains, and so
on. The core intuition, again, is that a phenomenally conscious state
will be a state *of which the subject is aware*.



What options does a first-order theorist have to resist this
conclusion? One is to deny that the data are as problematic as they
appear (as does Dretske 1995). It can be said that the unconscious
states in question lack the kind of fineness of grain and richness of
content necessary to count as genuinely *perceptual* states. On
this view, the contrast discussed above isn't really a difference
between conscious and unconscious perceptions, but rather between
conscious perceptions, on the one hand, and unconscious belief-like
states, on the other. Another option is to accept the distinction
between conscious and unconscious perceptions, and then to explain
that distinction in first-order terms. It might be said, for example,
that conscious perceptions are those that are available to
*belief* and *thought*, whereas unconscious ones are
those that are available to guide *movement* (Kirk 1994). A
final option is to bite the bullet, and insist that blindsight and
sensorimotor perceptual states are indeed phenomenally conscious while
not being *access*-conscious. (See Block 1995; Tye 1995; and
Nelkin 1996; all of whom defend versions of this view.) On this
account, blindsight percepts are phenomenally conscious states to
which the subjects of those states are blind. Higher-order theorists
will argue, of course, that none of these alternatives is acceptable
(see, e.g., Carruthers 2000; Rosenthal 2005).



Further, Lau and Rosenthal (2011) survey the empirical evidence
pertaining to the difference between higher-order theories and
first-order ones. While much is equivocal, and many questions are left
unanswered, they point to a pair of studies that support a
higher-order account. One is Lau and Passingham (2006), who are able
to demonstrate using carefully controlled stimuli that there are
circumstances in which people's subjective reports of visual
experience are impaired while their first-order discrimination
abilities remain fully intact. They also find that visual
consciousness in these conditions is specifically associated with
activity in a region of dorsolateral prefrontal cortex. Then in a
follow-up study Rounis et al. (2010) find that transcranial magnetic
stimulation directed at this region of cortex, thereby disrupting its
activity, also has a significant impact on people's meta-visual
awareness, but again without impairing first-order task
performance. The degree to which the prefrontal cortex
is *required* for having a conscious state and the view that
the prefrontal cortex is the likely site of *all* higher-order
thoughts are also the subject of vigorous continuing debate (Block
1995; Gennaro 2012, chapter nine; Kozuch 2014; Odegaard, Knight, and
Lau 2017). 



Most generally, then, higher-order theories of phenomenal consciousness
claim the following:



**Higher Order Theory (In General)**:
  

A phenomenally conscious mental state is a mental state (of a certain
sort--see below) that either is, or is disposed to be, the object
of a higher-order representation of a certain sort (see below).




Higher-order theorists do agree that one must normally become aware of
the lower-order state *non-inferentially* since mental states
can sometimes become targets of higher-order representation via
conscious inference without being phenomenally conscious. For example,
if I become aware of my unconscious desire to kill my boss because I
have consciously inferred it from a session with my psychiatrist, then
the characteristic phenomenal feel of such a conscious desire may be
absent. 



Still, there are then two main dimensions along which higher-order
theorists disagree amongst themselves. One concerns whether the
higher-order states in question are perception-like, on the one hand,
or thought-like, on the other. A thought is composed of or constituted
by concepts. Those taking the former option are
higher-order *perception* (often called
'inner-sense') theorists, and those taking the latter
option are higher-order *thought* theorists. The two theories
are therefore often abbreviated as HOP (higher-order perception) and
HOT (higher-order thought) theory. The other general disagreement is
internal to higher-order thought approaches, and concerns whether the
relevant relation between the first-order state and the higher-order
thought is one of *availability* or not. That is, the question
is whether a state is conscious by virtue of being *disposed*
to give rise to a higher-order thought, or rather by virtue of being
the *actual target* of such a thought. These are the three main
options that will now concern us. (A fourth will be considered in
section 6.)


## 3. Higher-Order Perception Theory



According to this view, humans not only have first-order
non-conceptual and/or analog perceptions of states of their
environments and bodies, they also have second-order non-conceptual
and/or analog perceptions of their first-order states of perception.
And the most popular version of higher-order perception (HOP) theory
holds, in addition, that humans (and perhaps other animals) not only
have sense-organs that scan the environment/body to produce
fine-grained representations, but they also have *inner* senses
which scan the first-order senses (i.e. perceptual experiences) to
produce equally fine-grained, but higher-order, representations of
those outputs. A version of this view was first proposed by the
British Empiricist philosopher John Locke (1690). In our own time it
has been defended especially by Armstrong (1968, 1984) and by Lycan
(1996, 2004).



A terminological point: '*inner*-sense theory'
should more strictly be called '*higher-order*-sense
theory', since we of course have senses that are physically
'inner', such as pain-perception and internal
touch-perception, that aren't intended to fall under its
scope. For these are first-order senses on a par with vision and
hearing, differing only in that their purpose is to detect properties
of the body, rather than of the external world (Hill 2004). According
to the sort of higher-order theory that is presently under discussion,
these senses, too, will need to have their outputs scanned to produce
higher-order analog contents in order for those outputs to become
phenomenally conscious. In what follows, however, the term
'inner sense' will be used to mean, more strictly,
'higher-order sense'.



We therefore have the following proposal to consider:



**Inner-Sense Theory**:
  

A phenomenally conscious mental state is a state with
analog/non-conceptual intentional content, which is in turn the target
of a higher-order analog/non-conceptual intentional state, via the
operations of a faculty of 'inner sense'.




On this account, the difference between a phenomenally conscious
percept of red and the sort of unconscious percepts of red that guide
the guesses of a blindsighter and the activity of the sensorimotor
system, is as follows. The former is scanned by our inner senses to
produce a higher-order analog state with the content *experience of
red* or *seems red*, whereas the latter states
aren't--they remain *merely* first-order states with the
analog content *red*; and in so remaining, they lack any
dimension of *seeming* or *subjectivity*. According to
inner-sense theory, it is the higher-order perceptual contents
produced by the operations of our inner-senses that make some mental
states with analog contents, but not others, available to their
subjects. 



One of the main advantages of inner-sense theory is that it can
explain how it is possible for us to acquire *purely recognitional
concepts* of experience. For if we possess higher-order perceptual
contents, then it should be possible for us to learn to recognize the
occurrence of our own perceptual states immediately grounded in those
higher-order analog contents. (Compare the way in which first-order
perceptual contents representing color and sound enable us the acquire
first-order recognitional concepts for colors and sounds.) And this
should be possible without those recognitional concepts thereby having
any conceptual connections with our beliefs about the content of the
states recognized, nor with any of our surrounding mental
concepts. This is then how inner-sense theory will claim to explain
the familiar philosophical thought-experiments concerning one's
own experiences, which are supposed to cause such problems for
physicalist/naturalistic accounts of the mind (Kripke 1972; Chalmers
1996). (For discussion of this 'phenomenal concept
strategy' see Carruthers and Veillet 2007.)



For example, I can think, '*R* [an experience as of red]
might have occurred in me, or might normally occur in others, in the
absence of any of its actual causes and effects.' So on any view
of intentional content that sees content as tied to normal causes
(i.e. to information carried) and/or to normal effects (i.e. to
teleological or inferential role), experience of type *R* might
occur without representing *red*. Likewise I can think,
'*R* might occur in someone without occupying the role of
*experience*, but rather (say) of belief.' In the same
sort of way, I shall be able to think, '*P* [an
experience of pain] might have occurred in me, or might occur in
others, in the absence of any of the usual causes and effects of pain.
There could be someone in whom *P* experiences occur but who
isn't bothered by them, and where those experiences are never caused
by tissue damage or other forms of bodily insult. And conversely,
there could be someone who behaves and acts just as I do when in pain,
and in response to the same physical causes, but who is never subject
to *P* types of experience.' If we possess purely
recognitional concepts of experience such as *R* and
*P*, then the thinkability of such thoughts is unthreatening to
a naturalistic approach to the mind.



Inner sense theorists are thus well placed to respond to
those who claim that there is an unbridgeable explanatory gap between
all physical, functional, and intentional facts, on the one hand, and
the facts of phenomenal consciousness, on the other (Levine 1983;
Chalmers 1996). And likewise they can explain the conceivability of
zombies without becoming committed to the existence of any
non-physical properties of experience (*contra* Chalmers 1996).
It is the conceptual isolation of our higher-order
recognitional concepts of experience that explains how there can be no
a priori entailment between physical, functional, and intentional
facts and the occurrence of states of type *R* or *P*
(where *R* and *P* express purely recognitional
concepts). 



Inner-sense theory does face a number of difficulties, however. One
objection is as follows (see Dretske 1995; Guzeldere 1995). If
inner-sense theory were true, then how is it that there isn't any
phenomenology distinctive of inner sense, in the way that there is a
phenomenology associated with each outer sense? Since each of the
outer senses gives rise to a distinctive set of phenomenological
properties, one might expect that if there *were* such a thing
as inner sense, then there would also be a phenomenology distinctive
of its operation. But there doesn't appear to be any.



This point turns on the so-called 'transparency' of our
perceptual experience (Harman 1990). Concentrate as hard as you like
on your 'outer' (first-order) experiences--you
won't find any *further* phenomenological properties
arising out of the attention you pay to them, beyond those already
belonging to the contents of the experiences themselves. Paying close
attention to your experience of the color of the red rose, for
example, just produces attention to the *redness*--a
property of the rose. Put like this, however, the objection just seems
to beg the question in favor of first-order theories of phenomenal
consciousness. It assumes that
first-order--'outer'--perceptions already have a
phenomenology independently of their targeting by inner sense. But
this is just what an inner-sense theorist will deny. And then in order
to explain the absence of any kind of higher-order phenomenology, an
inner-sense theorist only needs to maintain that our higher-order
perceptions are never themselves targeted by an inner-sense-organ
which might produce *third*-order analog representations of
them in turn.



Another objection to inner-sense theory is as follows (see Sturgeon
2000). If there really were an organ of inner sense, then it ought to
be possible for it to malfunction, just as our first-order senses
sometimes do. And in that case, it ought to be possible for someone to
have a first-order percept with the analog content *red*
causing a higher-order percept with the analog content
*seems-orange*. Someone in this situation would be disposed to
judge, 'It's red', immediately and non-inferentially (i.e.
not influenced by beliefs about the object's normal color or their own
physical state). But at the same time they would be disposed to judge,
'It *seems* orange'. Not only does this sort of
thing never apparently occur, but the idea that it might do so
conflicts with a powerful intuition. This is that our awareness of our
own experiences is *immediate*, in such a way that to
*think* that you are undergoing an experience of a certain
sort *is* to be undergoing an experience of that sort. But if
inner-sense theory is correct, then it ought to be possible for
someone to believe that they are in a state of *seeming-orange*
when they are actually in a state of *seeming-red*. (The
problem of misrepresentation will addressed further below in sections
6 and 7.)



A different sort of objection to inner-sense theory is developed by
Carruthers (2000). It starts from the fact that the internal monitors
postulated by such theories would need to have considerable
computational complexity in order to generate the requisite
higher-order experiences. In order to perceive an experience, the
organism would need to have mechanisms to generate a set of internal
representations with an analog or non-conceptual content representing
the content of that experience, in all its richness and fine-grained
detail. And notice that any inner scanner would have to be a physical
device (just as the visual system itself is) which depends upon the
detection of those *physical* events in the brain that are the
outputs of the various sensory systems (just as the visual system is a
physical device that depends upon detection of physical properties of
surfaces via the reflection of light). For it is hard to see how any
inner scanner could detect the presence of an experience *qua*
experience. Rather, it would have to detect the physical
*realizations* of experiences in the brain, and construct the
requisite higher-order representation of the experiences that those
physical events realize, on the basis of that physical-information
input. This makes it seem inevitable that the scanning device that
supposedly generates higher-order experiences of our first-order
visual experience would have to be almost as sophisticated and complex
as the visual system itself.



Given this complexity in the operations of our organs of inner sense,
there should be some plausible story to tell about the evolutionary
pressures that led to their construction (Pinker 1994, 1997). But
there would seem to be no such stories on the market. The most
plausible suggestion is that inner-sense might have evolved to
subserve our capacity to think about the mental states of
conspecifics, thus enabling us to predict their actions and manipulate
their responses. (This is the so-called 'Machiavellian
hypothesis' to explain the evolution of intelligence in the
great-ape lineage. See Byrne and Whiten 1988, 1998; and see Goldman
2006, for a view of inner sense of this sort.) But this suggestion
presupposes that the organism must *already* have some capacity
for higher-order *thought*, since it is such thoughts that
inner sense is supposed to subserve. And yet as we shall see shortly
(in section 5), some higher-order theories can claim all of the
advantages of inner-sense theory as an explanation of phenomenal
consciousness, but without the need to postulate any 'inner
scanners'. 



Lycan no longer holds HOP theory (Sauret and Lycan 2014) mainly
because he now thinks that some sort of *attention* to
first-order states is sufficient for an account of conscious states
and there is little reason to suppose that the attentional mechanism
in question is a higher-order representational state (see also Prinz
2012).


## 4. Higher-Order Thought Theory (1): Actualist



Actualist higher-order thought (HOT) theory is a proposal about the
nature of state-consciousness in general, of which phenomenal
consciousness is but one species. Its main proponent has been
Rosenthal (1986, 1993, 2005). The proposal is this: a conscious mental
state *M*, of mine, is a state that is actually causing an
activated thought (generally a non-conscious one) that I have
*M*, and causing it non-inferentially. (The qualification
concerning non-inferential causation will be discussed in a moment.)
An account of phenomenal consciousness can then be generated by
stipulating that the mental state *M* should have some causal role
and/or content of a certain distinctive sort in order to count as an
experience (e.g., with an analog content, perhaps), and that when
*M* is an experience (or a mental image, bodily sensation, or
emotional feeling), it will be phenomenally conscious when (and only
when) suitably targeted. The HOT is typically of the form: 'I am
in mental state M.'



We therefore have the following proposal to consider:



**Actualist Higher-Order Thought Theory**:
  

A phenomenally conscious mental state is a state of a certain sort
(e.g. with analog/non-conceptual intentional content, perhaps) which
is the object of a higher-order thought, and which causes that thought
non-inferentially.




As noted earlier, Rosenthal interprets the non-inferential requirement
as ruling out only *conscious* inferences in the generation of
a consciousness-making higher-order thought. This enables him to avoid
having to say that my unconscious motives become conscious when I
learn of them under psychoanalysis, or that my jealousy is conscious
when I learn of it by noticing and interpreting my own behavior. But
Rosenthal (2005) thinks that
*unconscious* self-interpretation is acceptable as a source of
the conscious status of the states thereby attributed. So if I arrive
at the thought that I am feeling cheerful by unconsciously noticing the
spring in my own step and the smile on my own face and drawing an
unconscious inference, my cheerfulness will thereby have been rendered
conscious. This aspect of Rosenthal's actualist form of
HOT theory would appear to be optional for a HOT theorist,
however.



In addition, and more controversially, Rosenthal (2005) thinks that
the occurrence of a suitably caused HOT is *sufficient* for
consciousness, even in the absence of any targeted first-order state
(usually called 'targetless' or 'empty'
HOTs). So I am undergoing a conscious experience of red provided that
I *think* that I am undergoing an experience of red, even if I
am actually in no first-order perceptual state whatever. This aspect
of Rosenthal's view, too, appears optional for an actualist HOT
theorist. Such a theorist can--and perhaps should--insist
that phenomenally conscious experience occurs when and only when a
first-order perceptual state causes a higher-order thought in the
existence of that state in a way that doesn't depend upon
self-interpretation. In recent years, the twin problems
of *misrepresentation* between HOTs and their first-order
targets as well as *targetless* HOT cases has led to
significant disagreement among HOT theorists (see section 7
below). 



The actualist HOT account avoids some of the difficulties inherent in
inner-sense theory, while retaining the latter's ability to
explain the distinction between conscious and unconscious perceptions.
(Conscious perceptions will be analog states that are targeted by a
HOT, whereas perceptions such as those involved in blindsight or
subliminal perceptions will be unconscious by virtue of *not*
being so targeted.) In particular, it is easy to see a function for
HOTs, in general, and to tell a story about their likely evolution. A
capacity to entertain HOTs about experiences would enable a creature
to negotiate the is/seems distinction, perhaps learning not to trust
its own experiences in certain circumstances, and also to induce
appearances in others, by deceit. And a capacity to entertain HOTs
about mental states (such as beliefs and desires) would enable a
creature to reflect on, and to alter, its own beliefs and patterns of
reasoning, as well as to predict and manipulate the thoughts and
behaviors of others. Indeed, it can plausibly be claimed that it is
our capacity to target higher-order thoughts on our own mental states
that underlies our status as rational agents (Burge 1996; Sperber
1996; Rolls 2004).



A common initial objection to HOT theory (or even HOP) is that they
lead to an infinite regress. It might seem that an infinite regress
results because a conscious mental state (M) must be accompanied by a
HOT, which, in turn must be accompanied by another HOT and so
on. However, the standard and widely accepted reply or explanation is
that when M is conscious, the HOT is not itself conscious (Rosenthal
1986, 2005). M is a first-order world-directed conscious state, such
as a desire or perception, accompanied by an unconscious HOT. But when
the HOT is itself conscious, there is a yet another higher-order (or
third-order) thought directed at the conscious HOT. This would be a
case of *introspection* according to HOT theory such that
one's attention is directed inward at M (such as introspecting
my desire). When this crucial distinction is overlooked, it can lead
to some misguided objections such as supposing that, according to HOT
theory, having any conscious state (even for animals and infants)
requires the ability to introspect.



One objection to HOT theory is due to Dretske (1993). We are asked to
imagine a case in which we carefully examine two line-drawings, say
(or in Dretske's example, two patterns of differently-sized
spots). These drawings are similar in almost all respects, but differ
in just one aspect--in Dretske's example, one of the
pictures contains a black spot that the other lacks. It is surely
plausible that, in the course of examining these two pictures, one
will have enjoyed a conscious visual experience of the respect in
which they differ--e.g. of the offending spot. But, as is
familiar, one can be in this position while not knowing
*that* the two pictures are different, or in what *way*
they are different. In which case, since one can have a conscious
experience (e.g. of the spot) without being aware that one is having
it, consciousness cannot require higher-order awareness.



Replies to this objection have been made by Seager (1994), Byrne
(1997), and Rosenthal (2005), among others. They point out that it is
one thing to have a conscious experience of the aspect that
differentiates the two pictures, and quite another to consciously
experience that the two pictures are differentiated by that aspect.
That is, consciously seeing the extra spot in one picture needn't mean
seeing that this is the difference between the two pictures. So while
scanning the two pictures one will enjoy conscious experience of the
extra spot. A HOT theorist will say that this means
undergoing a percept with the content *spot* *here* that
forms the target of a HOT that one is undergoing a
perception with that content. But this can perfectly well be true
without one undergoing a percept with the content *spot here in
this picture but absent here in that one*. And it can also be true
without one forming any HOT to the effect that one is
undergoing a perception with the content *spot* *here*
when looking at a given picture but not when looking at the other. In
which case the purported counter-example isn't really a
counter-example.



Another objection to actualist HOT theory is epistemological, and is
due to Goldman (2000). It turns crucially on the fact that the
consciousness-making higher-order thoughts postulated by the theory
are, themselves, characteristically *un*conscious. The
objection goes like this. When I undergo a conscious mental state
*M*, I generally know, or have good reason to believe, that
*M* is conscious. But how can this be, if what
*makes* *M* conscious is the existence of an
*un*conscious HOT targeted on *M*? Since I don't
know that this thought exists, it seems that I shouldn't be able
to know that *M* is conscious, either. As Goldman himself
acknowledges, however, this argument can only really work on the
assumption that actualist HOT theory is supposed to be some sort of
analytic or logical truth. Rosenthal has always made clear, however,
that the theory isn't intended to be a piece of conceptual
analysis, but is rather an account of the properties that
*constitute* the property of being conscious (see Rosenthal
1986, as well as his 2005). And the epistemological argument gets no
traction against this sort of view.



A different sort of problem with the actualist version of higher-order
thought theory relates to the huge number of thoughts that would have
to be caused by any given phenomenally conscious experience. (This is
the analogue of the 'computational complexity' objection
to inner-sense theory, sketched in section 3 above). Consider just how
rich and detailed a conscious experience can be. It would seem that
there can be an immense amount of which we can be consciously aware at
any one time. Imagine looking down on a city from a window high up in
a tower-block, for example. In such a case you can have phenomenally
conscious percepts of a complex distribution of trees, roads, and
buildings; colors on the ground and in the sky above; moving cars and
pedestrians; and so on. And you can--it seems--be conscious
of all of this simultaneously. According to actualist HOT theory,
then, it seems you would need to have a distinct activated HOT for
each distinct aspect of your experience--either that, or just a
few such thoughts with immensely complex contents. Either way, the
objection is the same. For it seems implausible that all of this
higher-order activity should be taking place (albeit non-consciously)
every time someone is the subject of a complex conscious
experience. What would be the point? And think of the amount of
cognitive/neural space that these thoughts would take up! (In
contrast, we know that neural tissue and activity are expensive; see
Aiello and Wheeler 1995; and we also know that as a result of such
constraints, the wiring diagram for the brain is about as efficient as
it is possible for it to be; see Cherniak
*et al*. 2004.)



This objection to actualist forms of HOT theory is considered at some
length in Carruthers (2000), where a variety of possible replies are
discussed and evaluated. Perhaps the most plausible and challenging
such reply would be to deny the main premise lying behind the
objection, concerning the rich nature of phenomenally conscious
experience. The theory could align itself with Dennett's (1991)
conception of consciousness as highly fragmented, with multiple
streams of perceptual content being processed in parallel in different
regions of the brain, and with no stage at which all of these contents
are routinely integrated into a phenomenally conscious perceptual
manifold. Rather, contents become conscious on a piecemeal basis, as a
result of internal or external
*probing* that gives rise to a HOT about the
content in question. This serves to convey to us the mere *illusion* of riches,
because wherever we direct our attention, there we find a conscious
perceptual content. (For a related reply, see Gennaro 2012, chapter six). 



It is difficult to know whether this sort of 'fragmentist'
account can really explain the phenomenology of our experience,
however. For it still faces the objection that the objects of
attention can be immensely rich and varied at any given moment, hence
requiring there to be an equally rich and varied repertoire of HOTs
tokened at the same time. Think of immersing yourself in the colors
and textures of a Van Gogh painting, for example, or the scene as you
look out at your garden--it would seem that one can be
phenomenally conscious of a *highly* complex set of properties,
which one could not even begin to describe or conceptualize in any
detail. However, since the issues here are large and controversial, it
cannot yet be concluded that actualist forms of HOT theory have been
refuted. This is particularly the case when one considers such
phenomena as change and inattentional blindness where subjects often
do not even *notice* somewhat significant changes occurring in
an image or video even within one's focal visual field (Simons
2000; Simons and Chabris 1999).



Another difficulty for actualist forms of HOT theory takes the form of
a puzzle: how can the targeting of a perceptual state by HOT make the
former 'light up', and acquire the properties of
'feel' or *what it is like-ness*? Suppose, for
example, that I am undergoing an unconscious perception of red. How
could such a percept then acquire the properties distinctive of
phenomenal consciousness merely by virtue of me coming to think (in
non-inferential fashion) that I am undergoing an experience of
red?



Rosenthal (2005) replies to this objection by pointing to cases in
which (he says) the acquisition and application of novel higher-order
concepts to our experience transforms the phenomenal properties of the
latter. Thus a course in wine-tasting can lead me to have experiences
of the wine that are phenomenally quite distinct from any that I
enjoyed previously (see also Siegel 2010; Gennaro 2012, chapter
six). And a course in classical music appreciation might lead to
changes in my experience of the sound of the orchestra, perhaps
distinguishing between the sounds of the oboes and the clarinets for
the first time. Since changes in higher-order concepts can lead to
changes in phenomenal consciousness, Rosenthal thinks, it is plausible
that it is the presence of higher-order thoughts targeting our
perceptual states that is responsible for the latter's
phenomenal properties *tout court*.



In response, an opponent of the theory might observe that some of the
concepts that one acquires in such cases do not appear to be
higher-order ones at all. Thus the concepts *oaky*
and *tanniny* that one acquires when wine-tasting pick out
secondary qualities *of the wine* (which are first-order), not
higher-order properties of our experience of the wine. And likewise
the concept *oboe* when applied in an experience is a
first-order concept of a sound type, not a higher-order concept of
one's experience of sound. The phenomenon here is quite general:
acquiring and applying new concepts in one's perception can
transform the similarity spaces and organization of one's
perceptual states. (Think here of the familiar duck/rabbit.) But it
appears to be a first-order phenomenon, not a higher-order one. At any
rate, there is considerable work for a HOT theorist to do here in
making out the case to the contrary.


## 5. Higher-Order Thought Theory (2): Dispositionalist



According to the dispositionalist HOT theory, the conscious status of
an perceptual state consists in its *availability* to
higher-order thought (Dennett 1978a; Carruthers 1996, 2000, 2005). As
with the non-dispositionalist version of the theory, in its simplest
form we have here a quite general proposal concerning the conscious
status of any type of occurrent mental state, which becomes an account
of phenomenal consciousness when the states in question are
experiences (or images, emotions, etc.) with analog content. The
proposal is this: a conscious mental event *M*, of mine, is one
that is disposed to cause an activated thought (generally a
non-conscious one) that I have
*M*, and to cause it non-inferentially.



The proposal before us is therefore as follows:



**Dispositionalist Higher-Order Thought Theory**:
  

A phenomenally conscious mental state is a state of a certain sort
(perhaps with analog/non-conceptual intentional content, and perhaps
held in a special-purpose short-term memory store) which is available
to cause (non-inferentially) higher-order thoughts about itself (or
perhaps about any of the contents of the memory store).




In contrast with the actualist form of theory, the higher-order
thoughts that render a percept conscious are not necessarily actual,
but potential. So the objection now disappears, that an unbelievable
amount of cognitive space would have to be taken up with every
conscious experience. (There need not *actually* be
*any* HOT occurring, in order for a given perceptual state to
count as phenomenally conscious, on this view.) So we might be able to
retain our belief in the rich and integrated nature of phenomenally
conscious experience--we just have to suppose that all of the
contents in question are simultaneously *available* to
higher-order thought. (Such availability might be realized by the
'global broadcast' of perceptual representations to a wide
range of conceptual systems in the brain, for drawing inferences, for
forming memories, and for planning, as well as for forming
higher-order beliefs. See Baars 1988, 1997, 2002.) Nor will there be
any problem in explaining why our faculty of higher-order thought
should have evolved, nor why it should have access to perceptual
contents in the first place--this can be the standard sort of
story in terms of Machiavellian intelligence.



It might well be wondered how their mere *availability* to
higher-order thoughts could confer on our perceptual states the
positive properties distinctive of phenomenal consciousness--that
is, of states having a *subjective* dimension, or a distinctive
subjective *feel*. The answer may lie in the theory of content.
Suppose that one agrees with Millikan (1984) that the representational
content of a state depends, in part, upon the powers of the systems
that *consume* that state. That is, suppose one thinks that
*what* a state represents will depend, in part, on the kinds of
inferences that the cognitive system is prepared to make in the
presence of that state, or on the kinds of behavioral control that it
can exert. In that case the presence of first-order perceptual
representations to a consumer-system that can deploy a 'theory
of mind', and that is capable of recognitional applications of
theoretically-embedded concepts of experience, may be sufficient to
render those representations *at the same time* as higher-order
ones. This would be what confers on our phenomenally conscious
experiences the dimension of subjectivity. Each experience would at
the same time (while also representing some state of the world, or of
our own bodies) be a representation that we are undergoing just such
an experience, by virtue of the powers of the 'theory of
mind' system. Each percept of green, for example, would at one
and the same time be an analog representation of *green* and an
analog (non-conceptual) representation of *seems green*
or *experience of green*. (Consumer semantics embraces not only
a number of different varieties of *teleosemantics*, but also
various forms of *inferential role semantics*. For the former,
see Millikan 1984, 1986, 1989; and Papineau 1987, 1993. For the
latter, see Loar 1981, 1982; McGinn 1982, 1989; Block 1986; and
Peacocke 1986, 1992). 



As an independent illustration of how consumer systems can transform
perceptual contents, consider prosthetic vision (Bach-y-Rita 1995;
Bach-y-Rita and Kercel 2003). Blind subjects can be fitted with a
device that transduces the output from a hand-held or head-mounted
video-camera into patterns of electrically-induced tactile stimulation
across the subject's back or tongue. Initially, of course, the
subjects just feel patterns of gentle tickling sensations spreading
over the area in question, while the camera scans what is in front of
them. But provided that they are allowed to control the movements of
the camera themselves, their experiences after a time acquire
three-dimensional distal intentional contents, representing the
positions and movements of objects in space.(Note that the patterns of
tactile simulations themselves become imbued with spatial content. The
subjects in question say that it has come to *seem* to them
that there is a spherical object moving towards them, for example.)
Here everything on the input side remains the same as it was when
subjects first began to wear the device; but the planning and
action-controlling systems have learned to interpret those states
differently. And as a result, the subjects' first-order
intentional perceptual contents have become quite different. Likewise,
according to dispositional HOT theory, when the 'theory of
mind' system has learned to interpret the subject's
perceptual states *as* perceptual states: they all acquire a
dimension of *seeming* or subjectivity.



Proponents of this account hold that it achieves all of the benefits
of inner-sense theory, but without the associated costs. (Some
potential draw-backs will be noted in a moment.) In particular, we can
endorse the claim that phenomenal consciousness consists in a set of
higher-order perceptions. This enables us to explain, not only the
difference between conscious and unconscious perception, but also how
analog states come to acquire a subjective dimension or
'feel'. And we can also explain how it can be possible for
us to acquire some purely recognitional concepts of experience (thus
explaining the standard philosophical thought-experiments concerning
zombies and such-like). But we don't have to appeal to the
existence of any 'inner scanners' or organs of inner sense
(together with their associated problems) in order to do
this. Moreover, it should also be obvious why there can be no question
of our higher-order contents misrepresenting their first-order
counterparts, in such a way that one might be disposed to make
recognitional judgments of *red* and *seems orange* at
the same time. This is because the content of the higher-order
experience is parasitic on the content of the first-order
one. Carruthers, therefore, also refers to this view as *dual
content* theory.



On the downside, the account isn't neutral on questions of
semantic theory. On the contrary, it requires us to reject any form of
pure input semantics, in favor of some sort of consumer semantics. We
cannot then accept that intentional content reduces to informational
content, nor that it can be explicated purely in terms of causal
co-variance relations to the environment. So anyone who finds such
views attractive will think that the account is a hard one to swallow.
(For discussion of various different versions of input semantics, see
Dretske 1981, 1986; Fodor 1987, 1990; and Loewer and Rey 1991.)



Moreover, Rosenthal (2005) has objected that dispositional HOT theory
can't account for our actual *awareness* of our conscious
mental states, since mere dispositions to entertain thoughts
doesn't make us aware of anything. Two replies can be made (see
Carruthers 2000, 2005). One is that, in virtue of our disposition to
entertain higher-order thoughts about it, a perceptual state will
*already* possess an analog higher-order content. It is this
content that makes us aware of the experience in question. But the
second reply is that there does, in any case, seem to be a perfectly
good dispositional sense of 'know' and
'aware'. As Dennett pointed out long ago (1978b), I can be
said to know, or to be aware, that zebras in the wild don't wear
overcoats, even though I have never actually considered the matter,
because I am *disposed* to assent to that proposition in light
of what I occurrently know.



In addition, Rowlands (2001) and Jehle and Kriegel (2006) have
objected that dispositional HOT theory can't explain the sense
in which the phenomenal properties of experience are
*categorical*. For the higher-order analog intentional contents
that our conscious perceptual states possess--and that are
identified with the 'feel' of experience--are said to
be constituted by the dispositional property that such states have, of
giving rise to HOTs about themselves. This objection,
however, appears to beg the question in favor of irreducible and
intrinsic qualia as an account of the distinctive properties of
phenomenally conscious states. In any case it doesn't seem to be an
objection against dispositional HOT theory as such, since it will
count equally against any representationalist theory of consciousness.
(For example, Tye 1995, explains consciousness in terms of the
*poisedness* of perceptual states to have an impact on belief
and reasoning, which is a dispositional notion.) Any theory that
proposes to reductively explain phenomenal consciousness in terms of
some combination of intentional content and causal role will be
explaining consciousness in terms that are at least partly
dispositional. 



A well-known objection to dispositionalist higher-order thought
theory, however, is that it may have to deny phenomenal consciousness
to most species of non-human animal. This objection will be discussed,
among others, in section 7, since it can be raised
against *any* form of higher-order theory.



Carruthers no longer holds dispositional HOT theory or, for that
matter, any form of higher-order theory and actually defends a version
of first-order representationalism instead (Carruthers 2017). He
responds to his own previous two main lines of argument against
first-order representationalism and then finds it unnecessary to
propose a higher-order theory in order to explain the difference
between unconscious and conscious states. Still, Carruthers thinks
that dispositional HOT theory is preferable to actualist HOT
theory.


## 6. Self-Representational Higher-Order Theories



The two most familiar forms of higher-order theory postulate the
existence of a pair of distinct mental states: a first-order
perceptual or quasi-perceptual state with a given content, and a HOT
or HOP representing the presence of that first-order state, thereby
rendering it conscious. Either one of these states can occur without
the other, although there may be a reliable causal relation between
them, such that certain types of first-order perception (e.g. attended
outputs of the temporal-lobe visual system) regularly cause
higher-order representations of themselves to be formed. In recent
years, however, a cluster of different proposals have been made that
would reject this independent-state assumption. Rather, the
relationship between the conscious state in question and the
higher-order state is said to be *constitutive*, or
*internal*. To some extent, this view is inspired by Brentano
(1874/1973) and the phenomenological tradition, including Sartre
(1956). (See Kriegel 2006, 2018; Kriegel and Williford 2006; Zahavi
2004; Miguens et al. 2016.) We can refer to these as
'self-representational' higher-order theories. (Kriegel
initially coined the term 'same-order monitoring theory'
but this was potentially misleading).



We therefore have the following proposal to consider:



**Self-Representational Theory**:
  

A phenomenally conscious mental state is a state of a certain sort
(perhaps with analog/non-conceptual intentional content) which also,
at the same time, possesses an intentional content,
thereby in some sense representing *itself* to the person who
is the subject of that state.




There are two basic types of self-representational theory, depending
on whether the constitutive relation between the conscious state and
the higher-order state is one of *identity*, on the one hand,
or *part-whole*, on the other. According to the former type of
account, it is one and the same perceptual state that is both
first-order (representing the world to us) and higher-order
(presenting itself to us). (Caston 2002, argues that Aristotle had a
theory of conscious perception of this sort.) Kriegel (2006) claims
that such accounts are rather mysterious from a naturalistic
perspective, but Carruthers (2000, 2005) and perhaps also Van Gulick
(2001, 2004) purport to provide naturalistic explanations of just this
sort of view. According to Carruthers, a first-order perceptual state
with analog content acquires, at the same time, a higher-order analog
content by virtue of its availability to a 'theory of
mind' faculty, together with the truth of some suitable form of
consumer semantics (as explained in section 5 above). Van Gulick can
be interpreted as defending a similar view, which likewise relies on a
form of consumer semantics/functional role semantics, which he labels
a 'Higher-Order Global State (HOGS) theory'. On this
account, globally broadcast first-order perceptual states acquire at
the same time a higher-order
*seeming* dimension though their availability to, and
incorporation into, higher-order models of the self and its relation
to the perceived environment. (What isn't entirely clear is whether
Van Gulick thinks that the resulting perceptual state *is* the
HOG state, or is rather a component *part* of the HOG
state--in which case he would be advocating a kind of part-whole
self-representational account.)


Kriegel's (2009) eventual view emphasizes and argues for the
claim that there is a ubiquitous conscious (but inattentive or
peripheral) self-awareness which accompanies all first-order
(attentive and outer-directed) conscious states. Gennaro (2012,
chapter five) rejects this view by, among other things, arguing that
it is difficult to make sense of such alleged pervasive peripheral
self-awareness especially when one is focused on outer-directed
tasks. It is at least not as clearly present as, say, outer-directed
peripheral vision in normal visual perception. At minimum, it is
notoriously difficult to settle these sorts of disagreements between
competing phenomenological claims.



Some varieties of part-whole self-representational theory take the
same general form as actualist kinds of HOT theory, in which a
first-order perceptual state with the content *analog-red* (as
it might be) gives rise to a higher-order thought that one is
experiencing red. But rather than claiming that it is the first-order
perception that becomes phenomenally conscious because of the presence
of the higher-order thought, what is said that the complex state made
up of *both* the first-order perception *and* the
higher-order thought becomes conscious. Gennaro (1996, 2008, 2012)
defends such a view which he calls the *wide intrinsicality
view* such that the HOT is better thought of as belonging to the
same overall complex state as its target. It is, however, not always
clear how this theory could offer any substantive benefits not already
obtainable from actualist HOT theory. Rather, the claim is merely that
a conscious state is one that contains two parts, one of which is an
awareness of the other. Kriegel himself (2003, 2006, 2009) and (as
Kriegel interprets him) Van Gulick (2001, 2004) emphasize that the
first-order perception and the higher-order judgment need to
be *integrated* with one another in order for the resulting
complex state to be phenomenally conscious. Kriegel argues that there
needs to be a kind of integration resulting from a psychologically
real process (as opposed to a theorist's definition) in order
for the resulting state to have causal powers that differ from those
of the first-order state/higher-order state pair.



Kriegel and Van Gulick do not give fully developed accounts of just
*why* the integration of first-order perceptions with
higher-order judgments should give rise to the properties that are
distinctive of phenomenal consciousness. But one plausible
reconstruction is as follows, modeled on the way that the
conceptualization of analog (non-conceptual) first-order perceptual
content can transform the latter's properties. Consider, for
example, the familiar duck/rabbit. When someone sees this figure for
the first time she may just experience a complex of curved lines,
representing nothing. But when she comes to see it *as* a
rabbit, those lines take on a certain distinctive organization (the
figure now has both a front and a back, for example), thereby
transforming the represented properties of the figure. Arguably what
happens in such cases is that the conceptual systems succeed in
deploying a recognitional template for the concept *rabbit*,
finding a 'best match' with the incoming non-conceptual
representations. Indeed, there is reason to think that just such a
process routinely takes place in perception, with conceptual systems
seeking matches against incoming data, and with the resulting states
possessing contents that integrate both conceptual and non-conceptual
(analog) representations (Kosslyn 1994; Carruthers 2000). The result
is a single perceptual state that represents *both* a
particular analog shape *and* a rabbit. Now suppose that when
such states are globally broadcast and are made available to the
systems responsible for higher-order thought, a similar process takes
place. Those systems bring to bear the concept *experience* or
the concept *seeing* to produce a further integrated perceptual
state. This single state will not only have first-order contents
representing the lines on the page, and representing a rabbit, they
will also have a higher-order content representing that one is
*experiencing* something rabbit-like. Hence the perceptual
state in question becomes 'self-presenting', and acquires,
as part of its content, a dimension of *seeming* or
*subjectivity*. (See also Gennaro 2005, 2012, for a related
line of argument in response to this sort of challenge.)



Picciuto (2011) points out, however, that Kriegel's form of
self-representational theory still permits a mismatch between the
first-order and higher-order components of the integrated state. For
there seems to be nothing in the structure of the account to rule out
the possibility of a first-order analog content *green*
becoming integrated with the higher-order judgment *I am
experiencing yellow*, for example. In order to avoid this
difficulty, Picciuto (2011) proposes an alternative form of part-whole
self-representational theory. (See also Coleman, 2015; Timpe, 2015.)
He does so by appropriating, and deploying for a novel purpose, the
idea of a *quotational* phenomenal concept, originally
introduced by Papineau (2002) and Balog (2009) as part of their
defense of physicalism against the arguments of Chalmers (1996) and
others. Picciuto's idea is that the relevant sort of complex
self-representational state will consist of a first-order perceptual
content combined with a higher-order concept like *experience*
that embeds, or 'quotes' that very perceptual
content. Given this structure, it will be impossible that there should
be a mismatch between the two. For the higher-order component of the
complex state is not a *judgment about* the experience
component (which would permit them to be mismatched) but rather a
concept that *quotes* the experience component.



All part-whole self-representational accounts differ from the
dual-content theory of Carruthers (2000, 2005) in the following way,
however: on Carruthers' account, the end-product can be entirely
non-conceptual. And in particular, the higher-order content possessed
by a conscious percept is a non-conceptual one, representing a
*seeming* of the first-order content of the state by virtue of
its availability to higher-order consumer systems. On all of the
part-whole accounts sketched above, in contrast, a conscious
perception is always partially conceptual, containing the higher-order
concept *experience* (or something similar) as part of its
content. There are probably multiple dimensions along which these two
sorts of theory could be compared, and each may have its own
advantages. 


## 7. Objections to a Higher-Order Approach



There have, of course, been a whole host of objections raised against
higher-order theories of phenomenal consciousness over the years.
(See, e.g., Aquila 1990; Jamieson and Bekoff 1992; Dretske 1993, 1995;
Goldman 1993, 2000; Guzeldere 1995; Tye 1995; Chalmers 1996;
Byrne 1997; Siewert 1998; Levine 2001; Rowlands 2001; Seager 2004;
Block, 2011.) Many of these objections, although perhaps intended as
objections to higher-order theories as such, are often framed in terms
of one or another particular version of such a theory. A general moral
to be taken away from the present discussion should then be this: the
different versions of a higher-order theory of phenomenal
consciousness need to be kept distinct from one another, and critics
should take care to state which version of the approach is under
attack, or to frame objections that turn merely on the
*higher-order character* of all of these approaches. I shall discuss a few
'local' objections first, before discussing some generic
ones.


### 7.1 Local objections



A good many objections against specific versions of higher-order
theory have already been discussed above. Thus in section 3 we
discussed Dretske's (1995) 'lack of any higher-order
phenomenology' objection to inner sense theory (which
*only* targets inner sense theory). And in section 4 we
discussed Dretske's (1993) 'spot' objection to actualist
higher-order thought theory, as well as Goldman's (2000)
epistemological objection, each of which appears to apply only to HOT
theories. Of course some of the objections discussed above target more
than one version of higher-order theory, while still not being fully
general in scope. Thus the cognitive/computational complexity
objections discussed in sections 3 and 4 apply to inner sense theories
and to actualist HOT theories, but not to dispositionalist HOT or to
some self-representational theories.



Another 'local' objection (which is actually a
generalization of a variant of the misrepresentation problem discussed
in connection with inner sense theory in section 3 above) is the
targetless higher-order representation problem (Byrne 1997; Neander
1998; Levine 2001). This is confronted by both inner sense theory and
actualist HOT theory (but not by either dispositionalist HOT or
self-representational theories, according to which the relevant
higher-order state can't exist in the absence of the targeted
state). For in each case it seems that a higher-order experience of a
perception of red, say, or a HOT about a perception of red, might
exist in the absence of any such perception occurring. So it
would *seem* to the subject that she is experiencing red, or
she might *think* that she is experiencing red, in the absence
of any such experience. (Note that the point isn't just that she
might undergo such a seeming in the absence of anything really
red. Rather, the point is that she might not really be undergoing any
sort of visual experience *as of red* at all.) In which case,
does the subject have a phenomenally conscious experience *as
of* red, or not?



Both Lycan (1996) and Rosenthal (2005) are sanguine in the face of
this objection. Each allows that targetless higher-order
representations are a possibility (albeit rare, perhaps), and each
opts to say that the subject in such a case is phenomenally conscious.
But each denies that this is a problem for their account. Lycan, for
example, insists that it is surely possible that it might
*seem* to someone that she is feeling pain when really no
relevant first-order representation of pain is present. (He suggests
that the effects of morphine, which leaves patients saying that their
pain feels just as it was, but that they no longer care, might
constitute such a case.) And surely such a person would have a
phenomenally conscious experience *as of* pain. Rosenthal,
likewise, uses pain as an example. He points to cases of dental
patients who initially experience pain in the dentist's chair despite
the fact that the relevant nerves are completely destroyed. It seems
that their fear, combined with the noise and vibration of the drill,
causes them to mistakenly think that they are feeling pain. (When
the drilling is stopped, and their dead nerves are explained to them,
they thereafter experience only the sound and the vibration.) So this
would be a case in which a HOT about experiencing
pain is alone sufficient to induce a phenomenally conscious experience
*as of* being in pain. A critic, however, might respond that
the illusion is caused, instead, by a vivid *imagining* of
pain, rather than by a HOT about feeling pain. Alternatively, if a
HOT is causally involved it might be that a top-down expectation of
pain *causes* a first-order experience of pain, as opposed to
being *constitutive* of the feeling of pain. It might be
that *introspective* anticipation of pain causes the pain in
the first-place. (Note that this seems perfectly possible, since it is
the opposite of well-known placebo effects of expectation in reducing
pain.)


 The targetless HOT problem has recently become a very significant
topic of debate among HOT theorists as well as some critics (Block
2011; Rosenthal 2005, 2011; Weisberg 2011; Gennaro 2012, chapter four;
Wilberg 2010; Berger 2014, 2017; Brown 2015; Lau and Brown 2019) which
has also led some to advocate for other variants of HOT theory or to
clarify their own theories. Gennaro (2012) argues, for example, that
since the HOTs in question are typically themselves unconscious, it
makes little sense to suppose that these HOTs are phenomenally
conscious in the context of HOT theory, especially since a conscious
HOT would be an introspective state instead. Maintaining that an
unconscious HOT would yield the same subjective experience without any
target state seems to run counter to a central initial motivation of
HOT theory, namely, to explain what makes a *first-order* state
conscious. Thus, the first-order state must exist first in order to be
rendered conscious by an appropriate and accompanying HOT with some
sort of corresponding conceptual content. If both aren't
present, then no relevant conscious state occurs (see also Wilberg
2010). Berger (2014), however, argues that consciousness is not a
property of states at all; instead, it is a property of individual
persons (that is, how my mental states appear to *me*). And
Brown (2015) challenges the very assumption that HOT theory is best
interpreted as a relational theory at all; instead, it is better
construed as a HOROR theory, that is, higher-order representation of a
representation, regardless of whether or not the target representation
exists. In this sense, HOT theory is better understood
as *non-relational* which also seems to be Rosenthal's
considered view in recent decades. The debate continues (Rosenthal
2018). 



In response specifically to Block (2011), Rosenthal (2011) and
Weisberg (2011) stress that the mere *seeming* of, say, being
in pain (provided by the HOT that one is in pain in the absence of
first-order pain) is sufficient for phenomenally conscious
pain. Consciousness is about mental *appearance*. It is not
clear that this fully addresses Block's point, which is that one
would not expect the mere thoughts that one feels pain
to *matter* to us in all the ways that pain matters. Block
develops this point with respect to the *awfulness* of pain. It
would be remarkable (indeed, mysterious) if a higher-order thought
should have all of the causal powers of the mental state that the
thought is about. And in particular, there is no reason to expect that
a HOT that one is in pain should possess the negative valence and
high-arousal properties of pain itself. But the latter are surely
crucial components of phenomenally conscious pain. If so, then a HOT
that one feels pain in the absence of first-order pain
will *not* be sufficient for the conscious feeling of pain. It
is also again important not to conflate introspection (conscious HOTs)
with mere unconscious HOTs. (See also Shepherd 2013.)



Yet another 'local' objection is targeted against
higher-order thought theories in particular (whether actualist or
dispositionalist). It presents such theories with a dilemma: either
they are attempts to explicate the *concept* of consciousness,
in which case they are circular; or they are attempts to provide a
reductive explanation of the *property* of being conscious, in
which case they generate a vicious regress (Rowlands 2001). The first
horn can be swiftly dismissed. For as Rosenthal (2005) and many others
have made clear, higher-order theories aren't in the business of
conceptual analysis. Rather, their goal is to provide a reductive
explanation of *what it is* for a state to be phenomenally
conscious. Our discussion will therefore focus upon the second
horn.



Rowlands thinks that HOT theories face a vicious regress because they
explain state-consciousness in terms of HOT, and because (Rowlands
claims) only *conscious* thoughts make us aware of the things
that those thoughts concern. He gives the example of coming to believe
that his dog is seriously ill. If he (Rowlands) thinks and behaves in
ways that are best explained by attributing to him the thought that
his dog is ill, but if that thoughts isn't entertained
consciously, then surely this won't be a case in which he
is *aware* that his dog is ill. So if we are to become aware of
our conscious states by entertaining higher-order thoughts about them,
then these thoughts will have to be conscious ones, requiring us to be
aware of them, in turn, via further higher-order thoughts that are
also conscious; and so on.



HOT theorists might respond in several ways: One is to challenge the
intuition that only conscious thoughts make us aware of things. Thus
it seems that Rowlands, when reflecting back on his dog-nurturing
behavior of recent days, could surely conclude something along the
lines of, 'It seems that I have been aware of my dog's
illness all along; that is why I have been behaving as I have.'
Another response would be to allow that there is *a* way of
understanding the concept of awareness such that a person only counts
as aware of something if the mental state in virtue of which they are
aware of that thing is itself a conscious one, but to deny that this
is the relevant sense of 'awareness' which is put to work
in HOT theories. A third option would be to stress the distinction
between *phenomenal* consciousness and state consciousness more
generally, claiming that there need be no regress involved in
explaining the former in terms of the latter, provided that some
separate account can be provided for the latter.


### 7.2 Generic objections



One generic objection, which can probably be recast in such a way as
to apply to any higher-order theory (although it is most easily
expressed against inner sense theory or actualist HOT theory), is the
so-called 'rock' objection (Goldman 1993; Stubenberg
1998). We don't think that when we become aware of a rock
(either perceiving it, or entertaining a thought about it) that the
rock thereby becomes conscious. So why should our higher-order
awareness of a mental state render that mental state conscious?
Thinking about a rock doesn't make the rock 'light
up' and become phenomenally conscious. So why should thinking
about my perception of the rock make the latter phenomenally
conscious, either?



An initial reply to this objection involves pointing out that my
perception of the rock is a *mental* state, whereas the rock
itself isn't (Lycan 1996). Since phenomenal consciousness is a
property that (some) mental states possess, we can then say that the
reason why the rock isn't rendered phenomenally conscious by my
awareness of it is that it isn't the right *sort* of
thing to
*be* phenomenally conscious, whereas my perception of the rock
is. This reply may be apt to strike the objector as trite. But perhaps
more can be said from the perspective of inner sense theory, at least.
Notice that my perception of the rock does, in one sense, confer on the
latter a subjective aspect. For example, the rock is represented from
one particular spatial perspective, and only some of its properties
(e.g. color) and not others (e.g. mass) are represented. Likewise,
then, with my perception of the rock. 



Similar replies to the rock objection are given by Van Gulick (2001)
and Gennaro (2005). Both point out that a rock isn't the kind of
thing that can be incorporated *into* a complex mental state
that involves higher-order representations, in the sort of way
required by a self-representational or HOT theory. In contrast,
whether actualist HOT theory can reply adequately to the rock
objection will depend on whether or not there is an adequate reply to
the problem considered in section 4, which challenges the actualist
HOT theorist to say why targeting a mental state with a HOT about that
state should cause the latter to 'light up' and acquire a
subjective dimension or
*feel*.



Another generic objection is that higher-order theories, when combined
with plausible empirical claims about the mental abilities of
non-human animals, will conflict with our common-sense intuition that
such animals enjoy phenomenally conscious experience (Jamieson and
Bekoff 1992; Dretske 1995; Tye 1995; Seager 2004). This objection can
be pressed most forcefully against higher-order *thought*
theories, of either variety, and against self-representational
theories; but it is also faced by inner-sense theory (depending on
what account can be offered of the evolutionary function of organs of
inner sense). Are cats and dogs really capable of having such
apparently complex HOTs which presumably contain mental state
concepts? Since there has been onsiderable dispute as to whether even
chimpanzees (and other primates) have the kind of sophisticated
'theory of mind' to enable them to entertain thoughts
about experiential states as such (Byrne and Whiten 1988, 1998;
Povinelli 2000), it seems implausible that many other species of
mammal (let alone reptiles, birds, and fish) would qualify as
phenomenally conscious, on these accounts (Carruthers 2000, 2005). Yet
the intuition that such creatures enjoy phenomenally conscious
experiences is a powerful one, for many people. (Witness Nagel's
classic 1974 paper, which argues that there must be something that it
is like to be a bat.)



Many higher-order theorists have attempted to resist the claim that
their theory has any such entailment (e.g. Gennaro 1996, 2004; Van
Gulick 2006). In each case, a common strategy is to claim that the
relevant higher-order representations are somehow
*simpler* than those tested for by those who do comparative
'theory of mind' research, hence leaving it open that
these simpler representations might be widespread in the animal
kingdom. Gennaro (1996), for example, suggests that although animals
might lack the concept *experience*, they can nevertheless be
capable of higher-order indexical thoughts of the form
'*this* is different from *that*' (where
'this' and 'that' might refer to experiences
of red and of green, respectively). The trouble here, however, is to
explain what makes these indexicals higher-order in content without
attributing concepts like *experience of green* to the animal.




Gennaro (2004) takes a somewhat different tack. While allowing that
animals lack the concept *experience of green*, he thinks that
they might nevertheless possess the (simpler) concept *seeing
green*. But here he faces a dilemma. There is, indeed, a simpler
concept of seeing, grounded in the capacity to track eye-direction and
line of sight. But this isn't necessarily a higher-order
concept. To say, in this sense, that someone sees green in just to say
that there is some green in the line in which their eyes are
pointed--no mental state needs to be attributed. In contrast, it
appears that any concept of seeing that is genuinely higher-order will
be one that it would be less plausible to attribute to most species of
animal (given the comparative evidence). Perhaps a first-order
explanation of experimental observations of animals is virtually
always possible (see, for example, Carruthers 2008). But Gennaro
(2012, chapter eight) ultimately argues that there is plenty of
evidence that many animals are capable of metacognition (thinking
about their own mental states) as well as mindreading (thinking about
other minds). For example, in the case of mindreading, rhesus monkeys
seem to attribute visual and auditory perceptions to others in more
competitive paradigms (Flombaum and Santos 2005) and crows and scrub
jays return alone to caches seen by other animals and recache them in
new places (Emery and Clayton 2001). Any evidence of deception or
empathy in animals would also seem to indicate some kind of
mindreading ability. In addition, many animals seem capable of
metacognition (including possessing self-concepts) as evidenced by the
presence of episodic memory, for example (Dere et al. 2006; see also
the essays in Terrace and Metcalf 2005; Hurley and Nudds 2006). A
related debate takes place with respect to infant consciousness and
the capacity of infants to have metacognitive and mindreading
abilities (see Gennaro 2012, chapter seven, for some
discussion). 



Van Gulick (2006), in contrast, suggests that all of the higher-order
representing sufficient to render an experience phenomenally conscious
can be left merely *implicit* in the way that the experience
enters into relationships with other mental states and the control of
behavior. So animals that lack the sorts of explicit higher-order
concepts tested for in comparative 'theory of mind'
research can nevertheless be phenomenally conscious. The difficulty
here, however, is to flesh out the relevant notion of implicitness in
such a way that not every mental state, possessed by every creature
(no matter how simple), will count as phenomenally conscious. For
since mental states can't occur singly, but are always part of a
network of other related states, mental states will always carry
information about others, thus implicitly representing them. It is
implicit in the behavior of any creature that drinks, for example,
that it is thirsty; so the drinking behavior implicitly represents the
occurrence of the mental state of thirst. 



Of course, the basis for the common-sense intuition that animals
possess phenomenally conscious states can even be challenged. (How,
after all, are we supposed to *know* whether it is like
something to be a bat?) And that intuition can perhaps be explained
away as a mere by-product of imaginative identification with the
animal. (Since our
*images* of their experiences are phenomenally conscious, we
may naturally assume that the experiences *imaged* are
similarly conscious (Carruthers 1999, 2000). But there is no doubt
that one major source of resistance to higher-order theories will lie
here, for many people, especially given various moral considerations
about animal pain and suffering. (For one set of attempts to defuse
this resistance, arguing that a higher-order account need have few if
any implications for our moral practices or for comparative
psychology, see Carruthers 2005, chapter nine; 2019, chapter eight.)
Of course, some will point out that there are also
enough *neurophysiological similarities* between (at least some
parts of) human and animal brains to justify attributions of, say,
pains, desires, and basic perceptual states. It is worth emphasizing
here that HOT theory does *not* say that having conscious
states requires having *introspective* states, that is, having
conscious HOTs. Conflating introspection with having mere unconscious
HOTs (and therefore simply having first-order conscious states) may
lead some to put forth a misguided straw man argument against HOT
theory.



A third generic objection is that higher-order approaches cannot
really *explain* the distinctive properties of phenomenal
consciousness (Chalmers 1996; Siewert 1998; Levine 2006). Whereas the
argument from animals is that higher-order representations
aren't
*necessary* for phenomenal consciousness, the argument here is
that such representations aren't *sufficient*. It is claimed,
for example, that we can easily conceive of creatures who enjoy the
postulated kinds of higher-order representation, related in the right
sort of way to their first-order perceptual states, but where those
creatures are wholly *lacking* in phenomenal consciousness.



In response to this objection, higher-order theorists will join forces
with first-order theorists and others in claiming that these objectors
pitch the standards for explaining phenomenal consciousness too high
(Block and Stalnaker 1999; Tye 1999; Carruthers 2000, 2005; Lycan
2001). They will insist that a reductive explanation of
something--and of phenomenal consciousness in
particular--doesn't have to be such that we cannot conceive
of the *explanandum* (that which is being explained) in the
absence of the *explanans* (that which does the explaining).
(Indeed, we can also *explain why* no such explanation can be
forthcoming, in terms of our possession of purely recognitional
concepts of experience.) Rather, we just need to have good reason to
think that the explained properties are *constituted*
*by* the explaining ones, in such a way that nothing
*else* needed to be added to the world once the explaining
properties were present, in order for the world to contain the target
phenomenon. But this is hotly contested territory. And it is on this
ground that the battle for phenomenal consciousness may ultimately be
won or lost.



Before we close, it is worth considering a variant of the third
generic objection that we have just been discussing, which need
involve no commitment to the latter's demanding standards of
explanation. For it might be said that self-representing mental states
(or indeed any of the theoretically-relevant kinds of pairing of
first-order with higher-order representations) might occur within the
unconscious mind, without (of course) thereby becoming conscious (Rey,
2008). Suppose that some version of Freudian theory is true, for
example. Might there not be higher-order thoughts about the
subject's experiences occurring within the unconscious mind,
formed while the latter tries to figure out how to get its messages
past the 'censor' and expressed in speech? So here again,
just as with the third generic objection, the claim is that the
occurrence of the sorts of representations postulated by higher-order
theories isn't
*sufficient* for phenomenal consciousness.



One sort of response to this objection would be to deny that such
purely unconscious higher-order cognition ever *actually*
occurs. Indeed, one might deny that it is even possible, given the
constraints provided by the evolution of cognitively demanding mental
functions (Carruthers 2000). But note that this reply will be
unavailable to any higher-order theorist who has opted to downplay the
cognitive demands of the capacity for higher-order representation in
response to the problem of animal consciousness. For if higher-order
representation is easily evolved, and is rife within the animal
kingdom, then there doesn't appear to be any reason why it
shouldn't evolve within unconscious sub-systems of the mind as
well. And in any case it is doubtful whether the mere *natural*
impossibility of higher-order representing within the unconscious mind
would be enough to rebut the objection. Since higher-order theories
claim that phenomenal consciousness is to be *identified* with,
or is
*constituted by*, the relevant sorts of higher-order
representing, we would need to show that the imagined occurrence of
the latter within the unconscious mind is *metaphysically*
impossible, not just that it is naturally so.



Other responses to the objection remain (Carruthers 2000, 2005). One
would be to allow that unconscious phenomenal consciousness is
possible, and to appeal to the distinction between *phenomenal*
consciousness and *access* consciousness to explain away the
seeming contradiction involved. Remember, phenomenally conscious
states are those that it is *like* something to be in, and that
possess a subjective *feel*; whereas access-conscious states
are those that are available to interact with some specified cognitive
processes (for example, they might be those that are reportable in
speech). So all we would be saying is that states with *feel*
can occur in ways that aren't (for example) reportable by the
subject. There is no contradiction here. An alternative possible
response would be to extend the higher-order theory in question to
include the relevant sort of access-consciousness as a further
component. A dispositional HOT theorist, for example, might say that a
phenomenally conscious state is one that *both* possesses the
right sort of dual content *and* that is reportable by the
subject. I shall not attempt to adjudicate between these possibilities
here.



(Objections have also been raised as to how (or if) HOT theory and
self-representational theories can account for various pathologies of
self-awareness or 'depersonalization disorders,' such as
somatoparaphrenia and thought insertion in schizophrenia. See the
essays in Gennaro 2015 for some discussion.)