CLADES, CAPGRAS, AND PERCEPTUAL KINDS Jack Lyons University of Arkansas
Perceptual states represent the world as being certain ways, as having certain properties.
Which ways and properties are these? When I hold out my hand and look at it, it seems that I
have a visual experience of a hand. One traditional view has held that my perceptual state is not
of a hand but merely of an array of color patches, or the like, which disposes me to believe that
there’s a hand without itself actually representing anything as being a hand; the perceptual state,
that is, is not actually of a hand. A very different sort of view might allow into the contents of
perceptual states not just hands, but perhaps even psychological states, semantic properties,
causal relations, such counterfactual properties as Gibsonian affordances, and maybe even highly
specific properties like that of being a pileated woodpecker. Either view purports to express a
deep fact about the nature of (human) perception, one that is not merely a matter of one’s
individual circumstances. Given my cognitive and perceptual apparatus, what ways can
perception represent the world as being? What sorts of properties are represented in perception?
What are the contents of perceptual states?
In case such questions do not seem intrinsically interesting, notice that how we answer
them is likely to have serious epistemological implications. If my perceptual states represent
things as hands rather than, say, color patches, this would go a long way toward a defense of the
claim that what I see is that there is a hand in front of me, and of the claim that my belief that
there is a hand in front of me is a perceptual belief. This latter claim would go a long way in
support of the view that beliefs about hands and the like are epistemologically basic—i.e.,
justifiable independently of evidential support from other beliefs. On the other hand, if
perception delivers to us not a world of tables and dogs and hands, but an array of color patches
at various retinal locations or an aggregate of variously angled uniformly colored surfaces at
egocentrically specified locations, then our beliefs about the former would presumably have to be
inferred from beliefs about the latter, which would strongly suggest that beliefs about hands and
tables and such are neither perceptual beliefs nor epistemologically basic.
What properties do perceptual states represent things as having? I want to give a partial
answer to this question, by answering a different question, about what I will call “perceptual
kinds”. My approach will be one that begins by taking seriously the phenomenology of
perception. There are reasons to be suspicious of a phenomenological approach, which is why I
have used a very different method elsewhere in addressing this question. In my (2005) I tried to
articulate the conception of perceptual systems implicit in cognitive neuroscience and used that
to specify the contents of perceptual states; the latter I claimed are simply whatever consciously
accessible representational states are tokened in these perceptual systems. In any case, my current
goal is to answer this same question about the contents of perceptual states, though this time by
appealing to phenomenological factors, which were intentionally absent from the cognitive
neuroscientifically motivated account just mentioned. The phenomenological approach has seen
a resurgence in popularity recently, and in the end, I think that the results of this
phenomenological investigation will mesh fairly well with the results of the scientifically
motivated approach, though I won’t argue that here.
It is common to argue directly from the phenomenology, e.g., “it seems to me that my
perceptual states represent this thing as a tree; therefore tree is part of the content of my
perceptual states”. Such arguments, however, do little to convince anyone who does not already
accept the relevant conclusions, and the resulting clash of intuitions has done little to recommend
this direct phenomenological method. Instead, I will argue indirectly, using phenomenological
considerations to develop a conception of “perceptual kinds” and using that to specify (in part)
I should note from the outset that my concern is not with conceptual vs. nonconceptual
content; that debate is about the “lower end”, as it were, of perceptual representation; my worries
are about the upper end. Nor is my concern with psychosemantics; the goal is not to start with a
set of perceptual states and determine their contents, but to take a set of contentful states as given
and determine which of them are perceptual. Finally, I frame the question in terms of the contents
of perceptual states; the question is frequently approached instead in terms of the contents of
experience (see, e.g., Siegel 2005). I do it my way, because, for reasons that will become more
clear below, (a) not all experience is perceptual, and (b) not all perceptual states are obviously
experiential (or at least, not all differences in the content of the perceptual states are comfortably
viewed as differences in the content of perceptual experience).
Before explaining the notion of perceptual kinds and its relation to the contents of
experience, I want to say a bit more about what options one might take concerning the contents
of perception, the options among which my notion of perceptual kinds is supposed to help us
1. LIBERAL AND CONSERVATIVE THEORIES OF PERCEPTUAL CONTENT
It is well known that there is something like a continuum along which various theories
about the content of perception might fall. A conservative theory of the contents of perceptual
states is one that tries to locate as much content as possible outside of perception; a liberal theory
would allow a great deal of content to count as perceptual. The notion of a continuum here is
useful even though obviously flawed if taken too strictly. I will concentrate on visual
representation, though analogous claims could be made for other sense modalities.
Locke’s theory of sense perception (1690/1970) is in most respects, quite conservative:
“When we set before our Eyes a round Globe, of any uniform colour . . ., ‘tis certain, that the
Idea thereby imprinted in our Mind, is of a flat Circle variously shadow’d, with several degrees
of Light and Brightness coming to our Eyes. But . . . the Judgment . . . frames to itself the
perception of a convex Figure and an uniform Colour . . . (p. 145).” Russell expresses a similar
view (1912/1997), and such a restrictive construal of perceptual states was central to the
introspectionist psychology of the 19th century (see, e.g., Titchener 1910/1926) and a main reason
for the movement’s infamous need for trained introspectors. A “noninferential theory”, as I will
call these, employs an emphatic distinction between perception and inference, holding that an
inferential state is eo ipso not a perceptual state.
A more liberal view would resist drawing the line just here and allow that even though
certain features are inferable from earlier representations, even though representations of surface
boundaries and orientations may in fact be generated by an actual computational process of
unconscious inference, these inferred representations are nevertheless elements of perceptual
states. Such unconscious inference is arguably not inference in a sense that necessarily precludes
perception; and the mere fact that surface orientations are in some sense inferable from shading
does not obviously indicate that no representations of orientation are perceptual.1
Thus one might hold a view slightly more liberal than the noninferential view by
allowing, in addition to the features countenanced by the latter, that visual states also represent
surface boundaries, discontinuities, and orientations. Perhaps amodal completions, size and
shape constancy, and the like are also represented perceptually, rather than inferentially.
as well. We might hold the contents of perceptual states to be roughly similar to Peacocke’s
(1992) scenarios, or to the contents of Marr’s 2½-D sketch (1982). We might allow additional
computation or inference, to the point that perceptual states provide viewpoint independent
representations, replete with information about the sides of the object that are hidden from view.
If we are willing to allow inferred information to figure into the contents of perceptual
representations, we might admit as visual the representations of solidity, opacity, object
boundaries, and 3-D properties like cylindricality and such.
Taking all of these even further, we might claim that visual states represent objects as
members of commonsense categories; i.e., as chairs, dogs, mountains, rocks, and the like. This
sort of view strikes me as quite a bit more liberal than the ones just mentioned. Classifying some
particular thing as a rock, or a chair, involves relating that particular to other, absent, perhaps
nonexistent objects, in a way that representing something as presenting an elliptical aspect from
this angle, or even as being to the left of the green blob, does not. In addition, the inferential-
1 Another way to a more liberal view is to claim in Gibsonian spirit that we “directly pick
up” high-level information about tables and rocks and such. Even if this worked as apsychological theory of perception, it addresses only part of the motivation behindnoninferentialism. There is an epistemological motivation as well, according to which if onepiece of information is inferable from another and the latter is perceptually accessible to us, theformer is nonperceptual. So the last clause above, or something of the sort, is still be needed. cum-perceptual processes posited by the category theory go much further beyond their inputs
than do the processes posited by the more conservative theories. Plausibly, what makes
something a dog is that it has a particular genotype; what makes something a chair is that it was
built to serve a particular function. Such categorization involves inference to unperceived
essences on the basis of features that are merely statistically related to doghood and chairhood.
All representations represent things as belonging to categories; it’s just that the categories
invoked by the more conservative views are categories like trapezoidal-looking thing or shinysurface as opposed to brick, bat, and boat. As we will see shortly, what is important for this view
is that the represented categories occur at the level of commonsense categories, not that they
necessarily are themselves commonsense categories. It is categories at this level that we normally
have in mind when speaking of categories in these contexts, so I’ll reserve the term “category
theory” for one that holds that perceptual states represent things as belonging to commonsense
categories and/or categories at this same level.
Category theories invite a host of questions about which categories are represented.
Suppose something can look like a shoe. Can it look like a size 11.5 Brooks Cascadia? Can it
look like—i.e., look to be—the very shoe I lost on the bus last month? Certain fine-grained
discrimination tasks, like sexing day-old chicks or telling a genuine DaVinci painting from a
counterfeit, might count as visual, if the relevant categories are perceptually represented.
But what is to stop us from going even further? Gibson (e.g., 1979) famously held that we
perceive “affordances”, that we see things in terms of what they offer us: graspable protrusions,
swimmable volumes and the like. This is perhaps most plausible regarding evolutionarily salient
affordances, like food and shelter and the like; it amounts to the claim that perceptual
representations can have counterfactual content: if I were to do so-and-so, such-and-such would
(likely) result. Sean Kelly (1999) holds not only that perceptual states have counterfactual
content, but that they have normative counterfactual content: if I were to do such-and-such, I’d
have better experiences, i.e., my view would be closer to optimal. Susanna Siegel (2006) holds
that perceptual states represent (some) natural kinds and also that they represent semantic
properties. And though he never meant to have a liberal view about perception, Locke
(1690/1970) seems to have been forced by his empiricism into the claim that we perceive causal
These conservative and liberal proposals vary along a number of dimensions, not just one.
The two that interest me the most are the distinctions between high and low level properties on
the one hand and subordinate and superordinate categories on the other. In some fairly intuitive
sense, category theories ascribe to the contents of perceptual states “higher level properties” than
do noninferentialist theories. The noninferentialist says we see (perceptually represent something
as) “a circle variously shadow’d”; a more liberal view that we see a uniformly colored surface
with a certain smoothly continuously changing orientation; more liberal yet that we see a solid
sphere; the category theory that we see a bowling ball. The difference here is often described in
terms of high and low level properties (e.g., Siegel 2005, 2006): the liberal theorist allows
“higher level” properties to be contents of perception than does the conservative theorist. This is
standard and convenient terminology, but it is important not to be misled by it. The higher/lower
level property distinction invoked here is clearly not the standard higher/lower level property
distinction in metaphysics, which is cashed out in terms of (asymmetric) supervenience.2 The
properties of interest to the more liberal theories do not supervene on the properties of interest to
the noninferential view, for the relation is explicitly contingent. The “low level” properties are
indicative of, but not metaphysically sufficient for, the instantiation of the “high level”
The fundamental distinction here seems to be a psychological rather than a metaphysical
one; our views about which properties are high and low level are parasitic on our tacit
assumptions about perceptual processing. We can distinguish higher and lower level
representations in terms of causal dependencies (the higher level states/representations causally
depend on the lower level states, but not vice versa) and distinguish high and low level properties
in terms of these (the higher level properties are the ones represented by the higher level states).
Thus, the question of whether perceptual states represent high or low level properties becomes
the question: at what stage in perceptual processing do the states cease to be genuinely
perceptual? For example, is so-called “late vision” genuinely vision? Is representation of
causation, of affordances, of category membership perceptual or post-perceptual? Locke and
Russell might not have cast the matters in these terms (as Pylyshyn 2003 does), but surely they
thought that things seem spherical because they seem variously shadowed, and not vice versa.
One way to endorse a liberal theory of perception is to allow high level properties to be
represented in perception; another way is to broaden the range of categories one takes to be
2 Thus, liquidity is a higher level property than the intermolecular relations that realize
liquidity; liquidity supervenes on intermolecular relations but not vice versa. Similarly with painand the relevant brain states, etc. (Though supervenience is usually employed as an asymmetricrelation, the standard definitions make it technically only nonsymmmetric. Higher-leveled-nessreally does need to be asymmetric; hence the “not vice versa” clause.)
represented. The subordinate/superordinate category dimension concerns nature rather than
cognitive processing. Categories form nesting hierarchies: Rin Tin Tin is a particular German
shepherd, which is a kind of dog, which is a kind of animal, which is a kind of material object,
etc. Psychologists working on concepts frequently invoke “basic level” categories, like dog,chair, apple, which are to be contrasted on the one hand with subordinate categories, like
German shepherd, Macintosh, etc., and on the other hand with superordinate categories, like
animal, fruit, etc. (Rosch, et al. 1976). The basic level categories are by and large the
commonsense categories; they are the ones subjects usually cite in identification tasks.3 Thus, a
(more) liberal version of the category theory can be gotten by allowing (more) superordinate or
subordinate categories to be represented in perception.
These two dimensions, level of property and order of category, are orthogonal. Though
the category dimension is most evident toward the high end of the high/low level property
dimension, at the level of commonsense categories, category distinctions exist at every stage of
processing. Moderate views might agree about the level of processing that is compatible with
perceptual status but still disagree about what level of specificity perceptual representations
enjoy. One could hold that perceptual states represent something as being merely three-
dimensional, or as a roughly rectilinear block, or as a 1' x 4' x 9' block, etc. The early visual
category of shiny surface is subordinate to the early visual category of surface, and so on.
These are the basic options. Which do we choose, and how do we decide?
3 Intuitive though it is, the idea of a stable, unique, privileged basic level is a controversial
one (Jolicoeur, et al. 1984), and I won’t assume it has any psychological reality. I will invoke itmerely as a convenient way of talking about, say, subordinate categories full stop, withoutexplicit reference to the level to which they are subordinate. 2. PERCEPTUAL KINDS
Representation, perceptual and otherwise, is a twofold phenomenon, a matter of both
classification and description. To classify things is merely to sort them, to put them into classes,
to “file” certain things together and other things separately. Describing these classes is the very
different matter of labeling these files. All representation involves representing something as
something (as blue, or as a rock, etc.), and in that sense contains a descriptive element. Though
this element gets the most press, I want to focus on the other one. Standard, direct
phenomenological arguments concentrate on representation-as, thus primarily on the descriptive
component of perceptual representation. Concentrating on the classification component draws
our attention to perceptual kinds, the categories that are implicated in perceptual representation.
The objects of perception form similarity clusters. Some things look similar to each other;
others look different. There is a way that gray things look, and there is a way that round things
look, and the way that gray things look is different from the way that blue things look and also
from the way that round things look. Gray things, and round things, constitute perceptual kinds.
I use the term ‘kinds’ here for a reason. Kinds are classes that in some sense or other “cut
nature at its joints;” any division of the world into kinds must respect genuine differences and
similarities. To say that K is a kind is to say that the members of K constitute a homogeneous
group and are at the same time relevantly different from the members of other classes. Thus, the
kind gold is internally homogeneous, in that its members are all similar with respect to atomic
number; it is distinct from other kinds in that their members don’t have this atomic number.
Cambridge properties, like that of being my left ear or the Eiffel Tower, fail to pick out kinds
because the members of the corresponding classes have no real similarity that isn’t shared by
nonmembers. Arbitrarily truncated categories like all the gold in this room fail to constitute kinds
because their members are not—relevantly—different from other things.
There are various sorts of kinds, depending on the dimensions of homogeneity and
distinctness that unify and distinguish the groups. Microstructural kinds are categories whose
members are microstructurally similar to each other and microstructurally different from other
things. Functional kinds are categories whose members are functionally similar to each other and
functionally different from other things, and so on. If perceptual kinds are genuine kinds in this
sense, then they will have to exhibit the homogeneity and distinctness typical of kinds more
generally, and obviously the relevant dimensions of homogeneity and distinctness in this case
will be perceptual. Thus, K is a perceptual kind just in case the members of K are perceptually
similar to each other in some respects and perceptually different from other things in those same
respects. To say that cows constitute a visual kind is to say both that cows look similar to each
other and that cows have a distinctive look; i.e., they look unlike other things. The notion of a
perceptual kind will have to be relativized to a class of perceivers at a given time, though I will
usually leave the relativization tacit. What counts as a perceptual kind for me is quite different
from what counts as a perceptual kind for rattlesnakes, or sharks, or even (though this has yet to
Acid is a representative perceptual—in particular, a gustatory—kind. Acids are similar to
each other and dissimilar from non-acids in this respect: all acids taste sour and only acids taste
sour.4 For this reason, acid is a perceptual kind; the class of acidic things is perceptually
4 This is true in normal conditions, at least, e.g., at concentrations above detection
threshold but not so great as to burn the taste buds off the tongue, etc.
homogeneous in certain respects, and in these respects, the members are different from
nonmembers; the class is closed under the similarity relation that unifies it.
Perceptual similarity is a phenomenological notion. What makes acids a perceptual kind
is that the perceptual state normally produced by one acid is introspectibly similar to the
perceptual states normally produced by the others. Narrower perceptual kinds can be nested
within broader ones, e.g., scarlet might constitute a subkind of red. What is important is that if x
and y are members of some kind, then nothing that is not also a member of that kind lies between
x and y in phenomenological similarity space; topologically speaking, a perceptual kind thus
forms a convex region in similarity space. It does not follow from my understanding of
perceptual kinds that the members are indistinguishable, or that misrepresentation (false
negatives or false positives) is impossible; nor does it follow that the members of a given kind
cannot resemble members of another kind.
If K is a perceptual kind, then members of K are perceptually similar to each other yet
perceptually different from other things—that is, there is a way that members of K look. The
converse seems to be true as well; if there is a way that members of K look—in this robust sense
of the phrase—then K constitutes a perceptual kind.5 Thus, I take the following to be more or less
is a perceptual kind for S at t
there is a way that members of K perceptually appear (look, sound, etc.) for S at t
5 I realize this is a slightly specialized use of the phrase ‘there’s a way K members look’,
which might ordinarily be taken to impute similarity but not distinctness. What I mean when Isay that there is a way that members of K look is that there is a look that K members have andthat non-K-members don’t.
the members of K constitute a perceptual similarity class for S at t.
Water is not a perceptual kind; there is not a way that water looks. Though different
samples of water do look similar, they also look like too many other things: vodka, vinegar, etc.
Water is homogeneous but not (perceptually) distinct and thus does not constitute a perceptual
kind. Similarly, though there is a way that cows look, there is not a way that cows named Mabel
look; they don’t look any different from other cows. For slightly different reasons, there is not a
way that my colleagues look, even though I can easily identify them by sight; there’s a way that
Tom looks, and a way that Lynne looks, and a way that Barry looks, but there is not some way
they all look. The class is not homogeneous enough to constitute a perceptual kind. If my
department were highly nepotistic or had a facial tattoo policy, things might have been different.
Some classes seem to fail in their candidacy for perceptual kindhood for reasons of
heterogeneity (e.g., my colleagues), others (e.g., cows named Mabel) for lack of distinctness. In
fact, however, perceptual kindhood is neither simply a matter of similarity nor of distinctness, but
of similarity at a level of abstraction at which kind members look different from non-kind-members. My colleagues are members of a perceptual kind, but only of a fairly large one that
contains lots of other humans. Cows named Mabel might look different from other cows, but
Perceptual representation-as is intensional: the standard substitution arguments apply, but
perceptual kinds are extensional. Acid’s status as a perceptual kind doesn’t determine what
perceptual states represent acidic things as. My gustatory states represent things as sour, not as
acidic. This is one major reason for separating the (intensional) descriptive component of
representation from the (extensional) classification component; it is often easier to tell how our
perceptual states classify stimuli than what they represent these stimuli as. Ravens and crows
might look different to me, even though I don’t know which is which. They might therefore make
up distinct perceptual kinds for me, though it would be implausible to say my perceptual states
represent anything as being a crow. One can have crow as a perceptual kind without having the
ability to represent (perceptually or otherwise) something as a crow.
Another benefit of focusing on perceptual kinds is that it allows us to distinguish three
importantly different perceptual changes that might result from learning. First, learning might
affect the detection of low-level perceptual properties, thereby changing the way things actually
look or sound or taste, etc. Language learning seems to have this effect: what used to sound like
an uninterrupted string of phonemes now sounds like it has actual pauses between words, pauses
that are not visible in a spectrogram. Visual discrimination improves with practice, so that lines
whose orientations could not be visually distinguished come to be distinguishable. More
controversially, perhaps experience with certain images (e.g., the closure figures of Street ,
or R. C. James’s famous hidden dalmation picture) might result in new subjective contours. In
such cases, learning results in a given stimulus’s perceptually appearing in a way that is different
from the way it used to perceptually appear.
But this is not the only way perceptual learning could work. As a second possibility,
learning might take the form of integrating existing similarity classes with conceptual
information about the members. I have always been aware that these birds cluster together in
similarity space, close to, but separate from, this other cluster of birds. Now I learn that the
former group are called ‘crow’ and are a different species from the other group, which are called
‘raven’. Though it would be controversial, one might hold that this change counts as perceptual.
What I used to perceptually represent with a disconnected, arbitrary bit of Mentalese, I now
see—perceptually represent—as a crow. My present purpose is not to endorse this controversial
assertion but to distinguish such “perceptual learning” from other kinds.
A third, more interesting, type of perceptual learning might involve a reorganization of
the similarity spaces. Repeated experience or top-down conceptual information might result in
changes to my similarity groupings. Because it was important to me to distinguish (harmless)
water snakes from the similar looking (venomous) water moccasins, I have become perceptually
sensitive to the differences that are diagnostic; my similarity measurement gives, say, head shape
and body pattern more weight than overall color and tail length. These may be differences that I
had explicitly learned to be diagnostic, or just differences that covaried reliably enough to be
picked up by statistically sensitive perceptual learning mechanisms. In fact, they need not even be
diagnostic of the division I was after: I might accidentally end up with a similarity partition that
has nothing to do with an interspecific distinction but rather with males and females of a single
The primary problem that needs to be solved by learning here is one of sorting; it is a
problem of classification rather than of description (though there is a problem with that, too). If I
am given one known exemplar of A and one known exemplar of B and given some new target to
match to one of the two given exemplars, I might not know whether to sort by size, shape,
posture, color, or some other feature. One of the exemplars has a thicker body than the other, but
if A and B are not already perceptual kinds for me, I might have no idea whether this is an
idiosyncratic feature of this exemplar (at this time) or whether this is characteristic of its kind.
The point is that two particulars can come to look similar to each other without there
necessarily being any change in the intrinsic way either of them looks. Thus, this third kind of
possible perceptual learning would involve a change in an organism’s repertoire of perceptual
kinds, without requiring any change either in what the stimuli are represented as, or in the
intrinsic look of any individual member. 3. PERCEPTUAL KINDS AND PERCEPTUAL CONTENTS
I started out with questions about the contents of perceptual states, and I have been
discussing perceptual kinds instead. To extract even a partial answer to such questions from the
notion of perceptual kinds, we will need some linking principles. Because perceptual kindhood is
extensional, and property representation is intensional, we can’t simply hold that perceptual
states represent something as being K just in case K is a perceptual kind.6 There is a connection,
Perceptual states don’t represent acids as acidic but they do represent them as sour, and
the class of sour things just is the class of acids. The first front-wheel drive Cadillac constitutes a
perceptual kind for me, even though the property of being the first front-wheel drive car is not a
perceptible property and thus is not the content of a perceptual state. Instead, my perceptual states
represent members of that kind as 1967 Eldorados or, more likely, something not easily
translated into English. All perceptual states represent perceptual kinds, though how they
6 Strictly speaking, kinds are classes of things or of property instances, not properties
themselves, and the phrase ‘being K’ suggests that ‘K’ ranges over properties. Constant use of thephrase ‘perceptual states represent something as being a member of K’, however, would be bothcumbersome and potentially misleading—misleading in that the representations in question don’trepresent category membership as such; they represent things as being red or being cats or thelike, rather than as being members of the kind cat, etc. Consequently, I’ll use the moreconvenient phraseology.
represent them, i.e., what they represent them as, is an open question. The important point is that
something is being represented as something here; the class’s having a certain look is a
perceptual phenomenon, and it is not merely a matter of non-intentional qualia. If there are such
qualia, they aren’t the whole story. The perceptual kindhood of acidity implies that my perceptual
states represent acidity (though, again, not as acidity); all the more so for such high level
properties as that of being a ‘67 Eldorado. The perceptual similarity of a class of stimuli is, at
least in part, a matter of their being classified together by perceptual states. Thus, I think we can
say that if there is a way that K members look to S, then there is some F, coextensive with K,
such that some of S’s perceptual states represent something as being F.
I think we can say more than this. To say that something—literally—looks like a cow
(looks to be a cow, looks as if it is a cow, etc.) is to say, among other things, that there is a way
that cows look. This is why nothing can literally look like it is named Mabel—there isn’t a way
such things look. (Of course, something can look to be Mabel, whom I know to be named Mabel,
but this is different.) If water doesn’t look any different from vodka or vinegar, then something
might look to be a clear liquid, but it cannot look to be water. Nothing can visually appear to be
water, because there isn’t a way that water looks. This seems to hold for failures of homogeneity
as well as for failures of distinctness. Dangerous things aren’t perceptually homogeneous. There
isn’t a way that dangerous things look, though there is a way that tigers look and a way that
Chevy Corvairs look, etc. This is why our perceptual states don’t represent things as being
dangerous but as being tigers or Corvairs. Thus, it seems, a perceptual state can represent
something as being K only if there is a way that Ks look, i.e., only if K is a perceptual kind.
An opponent is sure to object to this claim by reminding us how natural it is to say that
certain things look dangerous. (“You sure you want to stand on that, Jim? It looks dangerous.”
“Odd that hippopotami are responsible for more human casualties than crocodiles; they don’t
look as dangerous.”) However, there are notoriously many senses of ‘looks’ and similar verbs;
such language does not always literally and accurately describe the content of perceptual states.
Some animals might literally look like predators or carnivores, and since I know these can be
dangerous, they might “look” dangerous in some oblique sense of ‘look’. But the property my
perceptual states thereby attribute to tigers is not one that perceptual states ever attribute to
Corvairs, except perhaps in odd cases of radical misrepresentation. The point is not merely that
the word ‘dangerous’ is multivocal when applied to cars, animals, and behavior; the point is that
there is not a univocal look shared by dangerous things. Thus, in order for something to “look” to
be dangerous, i.e., “look” to be a member of the class of dangerous things, it would have to
actually—literally—look to be a member of some class narrower than the class of dangerous
things, a class of things known or believed to be dangerous, e.g., a tiger, a shark, a predator, a
I have been arguing for two important principles:
PK1 : If K is a perceptual kind for S at t, then there is some F, coextensive with K, such that
some of S’s perceptual states at t represent something as FPK2: Some of S’s perceptual states at t represent things as being K only if K is a perceptual kind
If these principles are sound, they can take us some way toward answering questions about the
contents of perceptual states. PK1 supports a fairly liberal view about perceptual contents in that
it allows perceptual states to represent fairly high level properties. Perceptual states are not
limited to representing low level properties like color and surface orientation. There is a way that
rocks look and a way that cats look and (to some of us) a way that ‘67 Eldorados look; thus, these
are all perceptual kinds for the relevant agents. Therefore, properties coextensive with such
properties as being a cat or being a rock or being a ‘67 Eldo are represented in perception. This
is not quite a category theory, but it is fairly close. A category theory holds that perceptual states
represent things as instantiating properties at the level of commonsense categories, i.e., such
properties as being a cat or being a rock. I haven’t argued this, but I have argued that perceptual
states represent things as instantiating properties coextensive with these.
I am even willing to hold that some of the properties represented in perception may be
properties that seem intuitively to be very high level. I am inclined to think that for most social
species there is a way aggressive conspecifics look (though probably not a way that aggressive
animals, or even primates, look); aggression, annoyance, and other psychological states (in
humans, at least) may thus constitute perceptual kinds for us.
The view endorsed here is liberal not only with respect to the property dimension but also
with respect to the category dimension. The standard examples of basic level categories—bird,
rock, airplane, car, mountain, and the like—all make good candidates for perceptual kinds. Most
superordinate categories won’t constitute perceptual kinds, but some will. Importantly,
perceptual kinds can come and go as one ascends or descends the ontological hierarchy. Platypus
is a perceptual kind, and so is echidna, but monotreme (the class of egg-laying mammals, which
consists of just platypuses and echidnas) is not. Monotremes are no more perceptually similar to
each other than they are to quadrupeds more generally. Quadruped itself, however, is a
perceptual kind. So the perceptual kindhood enjoyed by echidnas is lost and then regained as one
climbs to more superordinate categories. This example reemphasizes the earlier claim that
perceptual kindhood is not simply a matter of intrakind similarity. It’s not that quadrupeds are
more homogeneous than monotremes (it is hard to see how this could be true, since the
quadrupeds contain the monotremes); it is just that monotremes don’t perceptually resemble each
other any more than they do the other quadrupeds.
The more interesting cases concern subordinate categories, where the main issue is
distinctness, rather than homogeneity. Perceptual learning has a “liberalizing” effect on
perception by rendering increasingly subordinate categories perceptually distinct, thus yielding
ever more perceptual kinds, and thus, according to PK1, increasing the field of perceptual
content. This might happen as a result of either the first or third type of perceptual learning
described above; either the intrinsic looks of the members change as a result of very low level
discrimination enhancement, or the similarity classes get restructured. Subjects with various
types of expertise—ornithologists, histologists, musicians, wine tasters, etc.—seem to have
highly subordinate categories as perceptual kinds and thus perceptually represent (properties
coextensive with) such fine-grained properties as being a year-old pileated woodpecker or even
being a genuine da Vinci painting. The result of perceptual learning seems to be genuinely new
perceptual kinds, of a level subordinate to the earlier perceptual kinds.7
The view I have been endorsing so far has been quite liberal. How far should it go? Is
7 Even without genuine perceptual learning or consequent changes in one’s repertoire of
perceptual kinds, a subject may attend to increasingly narrow regions of similarity space. This, itseems, would be more a matter of changing what the subject does perceptually represent than ofchanging what the subject can perceptually represent.
there any way to stop it from being excessively liberal? Even what I have argued so far has not
been without limitations. Although I am willing to allow highly subordinate categories as
perceptual kinds, this is only for the relevant experts, and even then, there are psychophysical
limits to how far this can go. No amount of learning is likely to give me more olfactory kinds
Notice also that many of the more lavish claims sometimes made about the contents of
perception involve perception-as, claims that my principles about perceptual kinds do not
commit us to. This is true of claims that go too far along the properties dimension and the
categories dimension as well. Thus, for example, even if some Gibsonian affordances constitute
perceptual kinds, this doesn’t imply that we represent things as affordances. There may be a way
that graspable protrusions look, but it doesn’t follow that they literally look graspable, as opposed
to looking some way that we know indicates graspability. In addition, there may be a
characteristic way that a proton looks as it travels across a cloud chamber, but even if moving
protons in cloud chambers constitute a perceptual kind, it is a huge and inadmissible leap to go
from this to the claim that our visual states represent things as protons. The inference from
perceptual kindhood to these very liberal—I think implausibly so—claims about the contents of
perception, i.e., perception-as, will require additional premises. In a way, the extensional nature
of my project is a limitation, but in a way it is an asset, for it does not lure one into giving facile
answers to what are genuinely very difficult questions of representation-as.
Just as PK1 supports a fairly liberal view of perception, PK2 can be used as a tempering
principle, to block certain immoderate claims about the scope of perceptual content. If K is not a
perceptual kind, then perceptual states don’t represent anything as being K. Water isn’t
perceptually distinct; hence water isn’t a perceptual kind; therefore our visual states don’t
represent anything as water. Causal relations are too perceptually heterogeneous to constitute a
perceptual kind. More importantly, narrower classes of causal relations are non-distinct in that
real causation doesn’t look any different from spurious correlation. Thus, we don’t perceive
causal relations. The same considerations hold for the above examples of non-perceptual-kind
classes: monotremes, my colleagues, and so on.
PK1 and PK2 give us principled grounds for accepting certain claims about the contents
of perception and for rejecting other claims. They do so without our having to make a
problematic and often question begging direct appeal to the phenomenology of the particular case
4. KINDS, PERCEPTUAL AND OTHERWISE
To apply these principles to a concrete proposal, consider a recent paper by Susanna
Siegel (2006), who claims that perceptual states represent things as instantiating such properties
as (a) the kind property of being a pine, and (b) the semantic properties of a bit of Cyrillic script,
presumably a property like meaning that grass is green. I think that neither property picks out a
perceptual kind, and thus, by PK2, neither property is represented in perception.
It is doubtful that our perceptual states can represent something as being a pine, though
for relatively uninteresting reasons. Pine is too heterogeneous to constitute a perceptual kind: the
towering Scotch pine and the shrubby mugho pine bear little perceptible resemblance that isn’t
shared by needle-leafed conifers more generally.8 However, at least one of her main points here,
if I understand her, is sound: conifer, Scotch pine, and other high-level properties can pick out
perceptual kinds and are thus reasonable candidates for properties represented in perception.9
Unfortunately, she tends to run this point together with a quite different one. Siegel’s official
conclusion is what she calls “Thesis K: In some visual experiences, some K-properties are
represented” (2006, 482). K-properties are so-called “[b]ecause they include, though are not
limited to, natural kind properties, and because one of my examples will involve such a property,
and finally because ‘kind’ begins with ‘k’” (482). It is never made clear exactly what K-
properties are, but part of the point seems to be that there is some interesting connection between
perceptual kinds and other kinds. On the contrary, however, I think that an extremely important
feature of perceptual kinds is that there is very little systematic connection between them and
What makes a collection of items constitute a perceptual kind is that they look similar,
but this is a famously rare and accidental feature of other kinds. The dimensions of homogeneity
and distinctness for ordinary kinds will frequently turn out to be imperceptible. Microstructural
kinds, for instance, are unified and individuated by microphysical structure, and this is a poor
predictor of perceptual kindhood. Gold is a microstructural kind, but it is not a perceptual kind:
white gold doesn’t look like normal gold, and a lot of what glitters (looks like gold) isn’t gold.
8 Pine is in this sense like dog. Several, presumably overlapping, types of dogs constitute
perceptual kinds, but dog itself doesn’t. There is no perceptual similarity class that contains shihtzus and great Danes and pointers but excludes wolves, jackals, and Tasmanian wolves.
9 Strictly speaking, it is only mature Scotch pines that make up a perceptual kind;
seedlings and saplings of various species all look alike to all but perhaps the very mostspecialized experts and horticulturists.
Even if microstructural similarity did provide for intrakind perceptual homogeneity,
microstructural difference from other things wouldn’t predict perceptual distinctness from other
kinds. Silver fails to make up a perceptual kind, not because some silver doesn’t have the
standard look but because too many other things look this way.
Functional kinds are famous for their perceptual heterogeneity, although some functional
kinds are perceptual kinds. Acid, in fact, is a paradigmatic example of both.10 Once again,
however, this is more or less coincidental.
Pine, of course, is neither a microstructural nor a functional kind, but a biological kind.
Though gold may be the philosopher’s standard example of a natural kind, biological kinds are in
many ways more illustrative. Biology has had to put a lot of explicit thought into its taxonomies,
and according to current orthodoxy, the primary biological kind is a clade, which is any branch
on the family tree of life that includes all the subsidiary limbs of that branch.11 The (folk)
category of reptiles is famously not a clade and therefore not a genuine biological kind. The most
recent common ancestor to turtles, alligators, lizards and snakes is also ancestral to birds, so any
grouping that excludes birds but includes all the rest fails to cut nature at the relevant joints.
Reptiles might constitute a perceptual kind, but they don’t constitute a well-formed family. Nor,
for very different reasons, do what we ordinarily think of as cacti. Cacti proper are an American
10 An acid is any compound that donates a hydrogen ion in (aqueous) solution (a base is
any compound that accepts one). Acid and base are thus functional kinds, contrary to theassumption on the part of many neoreductionists that chemistry reduces (in a strong sense that isincompatible with multiple realizability) to physics.
11 More strictly, a clade is a monophyletic grouping, which consists of an ancestor species
along with all of its descendants and only its descendants. For a brief overview of thecontroversies involved in systematics, see Sterelny and Griffiths 1999.
family, which, due to convergent evolution, look just like certain African euphorbiae. Together,
the cacti and euphorbiae constitute a perceptual kind, even though they are only distantly related
and thus not a biological kind. Similarly, the smallest perceptual kind that includes all the dogs
also includes some marsupials, like the Tasmanian wolf, and thus doesn’t map onto any
biological kind. Biologists, like other scientists, want a taxonomy that reveals real and interesting
similarities and differences. For them, the space that needs to be cut up to reveal this is
phylogenetic distance, not perceptual similarity space.12
Thus, there seems to be no systematic or otherwise interesting connection between
perceptual kinds and the various types of natural kinds. Perceptual kinds have their own
dimensions of homogeneity and distinctness, which are different from those of the various other
sorts of kinds. The real issue here is not whether perceptual states represent items as belonging to
kinds in any robust sense of the term, but whether it represents them as belonging to certain
categories, in particular, whether it represents them as belonging to commonsense categories and
other categories at or beyond that level on the properties dimension. What is important about
such classes as Scotch pine, gold, acid, and dog is not that they are kinds but that they are
represented at a relatively late stage of perceptual processing.
Siegel’s other main example involved the semantic properties of a bit of Cyrillic script.
Her claim appears to be that something can literally look like it means that grass is green, that
visual states can represent something as meaning that grass is green. I find this implausible.
Things that mean that grass is green do not constitute a perceptual kind, for there is not a way
12 There are taxonomic systems that are based on similarity and ascribe kindhood on
phenotypic grounds. Even so, however, the relevant similarities will typically be nonperceptual(including, e.g., phenotypic properties of internal organs, etc.).
that these things look, or sound or smell, etc. The problem is obviously not that visible script and
audible phonemes can share semantic properties while being perceptually very different; there
might simply be separate visuo-semantic and auditory-semantic kinds. The problem is rather that
bits of script that look nothing alike can share semantic properties, as can strings of phonemes
that sound nothing alike; even within a given perceptual modality, things that mean that grass is
It is clear that language learning affects perception, though this is most obvious in
audition, especially concerning the auditory perception of word boundaries. It is tempting to
conclude from such phenomena that some things sound like words after learning a language. But
this can’t be right. Lots of nonwords sound just like words; on any reasonable auditory similarity
metric, ‘fork’ sounds more like ‘vork’ than like ‘autoclave’. The more accurate account is more
interesting as well: there is a way that strings of phonemes sound and a way that word
boundaries sound (there’s an audible though endogenously imposed gap), but aside from these,
there isn’t some way that words sound. The case is analogous to what we want to say about
vision: certain visual states represent object boundaries, and there is a (fairly abstract) way that
object boundaries look, even though object is too heterogeneous to make up a perceptual kind.
Perhaps learning could make a string of Cyrillic text now look like a token of some
particular Russian sentence type.13 However, Siegel surely has a much stronger claim in mind:
13 Even this is unlikely, since the same sentence type can be written in uppercase or in
lowercase (not to mention in different fonts) and these will make up distinct perceptual kinds,since the lowercase letters frequently don’t look anything like their uppercase counterparts. Itworks a little better in Russian than it does in English, Russian having fewer upper/lower casedifferences. It is likely that one could get ‘O’ and ‘o’ to fall into a single kind that excludes ‘Q’by adjusting the similarity metric, e.g., weighing number of components more heavily than size. It is unlikely that any such adjustment could result in a kind that includes ‘Q’ and ‘q’ but leaves
that the perceived property is not just one shared by Russian sentence tokens of the same type,
but by various Russian sentence types, and various English, Finnish, and Arabic sentences as
A committed defender of this extremely liberal view could simply meet my complaint
head on by insisting that the property of meaning that grass is green is indeed a visual property
and that certain bits of English, Russian, and Arabic writing do indeed look similar—though only
to people in the know—not with respect to such properties as color or symbol shape or the like
but merely with respect to meaning that grass is green. Such a move clearly threatens to trivialize
the whole project, sending it down a very slippery slope. The liberal theorist is ill served by
holding that any property that can be ascribed on the ultimate basis of sensory stimulation is
therefore a perceptual property; the claim would no longer concern perception in any interesting
sense. In this new, relaxed sense of ‘look’, there is a way that things that mean p look, but in this
sense, there is also a way my colleagues look (like my colleagues), and a way that cows named
Mabel look, a way that my left ear and the Eiffel Tower look, etc.14
14 There is another move that might save an extremely liberal view. One could hold that
even though some class doesn’t constitute a visual kind, or an auditory kind, etc., in can still be aperceptual kind relative to some sense modality beyond the traditional list of five. In certaincases, this might even be plausible. Fodor (1983) suggests that language should be considered aperceptual system. A virtue of this proposal is that it is partially testable using standardneuropsychological methodology (e.g., double dissociations and the like); we can discoverempirically whether there is a separate language system that is in other ways similar to standardperceptual systems. Such tests should be of interest to anyone who wants to hold that we(literally) perceive God (e.g., Alston 1991), causation (Locke 1690/1975), familiarity, and therest. I take it that danger might be a perceptual kind for, say, Spiderman, who has a specialcognitive faculty, a special sense, for detecting danger. We don’t, and so it isn’t a perceptual kindfor us. I think this general approach is certainly interesting and might even be promising, but Iwon’t pursue it here, partly because I think that the proponents of the liberal view typically intend
There is something introspectible going on in us each time we see a piece of text that we
understand, but there is no reason to think that this something is visual. Not all experience that is
connected with perceptual experience is itself perceptual. Chocolate ice cream tastes good, and
bacon tastes good, but this doesn’t mean that the two taste similar; there isn’t a way that things
that taste good taste. (Sweet things taste alike in at least this sense: put a number of them in a
blender, and the result will still taste sweet. Put a number of things that taste good in a blender,
however, and all bets are off.) ‘Yummy’ (for lack of a better term) picks out an introspective
kind, perhaps, an experiential kind, maybe, but not a perceptual kind. The experience of
something’s tasting good to me is not a perceptual experience, any more than, if a certain odor
were to produce a feeling of nostalgia in me, this nostalgia would somehow be an olfactory state.
This is one major reason I have chosen to frame the issues here in terms of perceptual states,
Similarly, I experience a sense of familiarity in response to some stimuli, and these
experiences of familiarity resemble each other. But the stimuli don’t. Familiarity couldn’t
literally be part of the content of my visual experiences, for there simply isn’t a way that familiar
things look. My car keys look familiar, and the Santa Catalina mountains look familiar, but this
doesn’t imply that my keys look more like the Santa Catalinas than do the Sierra Nevadas, which
I’ve never seen before. The class of familiar things doesn’t constitute a perceptual kind.
Some authors have suggested (Siegel 2006, Siewert 1998) that something can’t look
familiar without ipso facto looking different than it did when it didn’t look familiar. “It is not just
that the visual experience is ‘accompanied by’ some ‘feeling of familiarity’—the way the face
for the claims to be about the familiar sense modalities, not about new hypothetical ones. looks to you changes” (Siewert 1998, 257; italics in original).15 It reads like an analytic
proposition to say that when an unfamiliar looking thing comes to look familiar, the way it looks
thereby changes; but in fact it is an equivocation. Contra Siewert, to “look familiar” is to be
accompanied by a (nonperceptual) feeling of familiarity, and this can happen without any change
in the perceptual states these things produce.
I have been arguing this on the basis of PK2, but the famous Capgras delusion (Capgras
and Reboul- Lachaux 1923, Ellis and Young 1990) seems to provide an actual case in point.
Patients with this syndrome are convinced that certain familiar things, especially spouses and
family members, have been replaced by perfect imposters. The delusion is sometimes modality
specific, so a patient will recognize his mother unproblematically when she calls on the telephone
or speaks from the other room, but if she is presented visually, he is convinced it is not his real
mother but a lookalike posing as his mother. Central to the syndrome is that the patient insists
that it is not his mother and at the same time that it looks exactly like his mother. The standard
explanation of this phenomenon (Ellis and Young 1990, Hirstein and Ramachandran 1997) is
that the patient’s visual system is intact, producing a ‘mother’ output just as it normally would,
but that this output does not get fed in the normal way into the affective system, so the patient
does not have the normal emotional response that a family member ought to evoke. Thus, the
15 I have had a number of people offer the same objection in conversation. I suggested
elsewhere (Lyons 2005) that perceptual learning might change the way things look, i.e., changethe way perceptual states represent things as being, without changing the perceptual experience. (This is the second reason for framing the issue in terms of perceptual states rather thanexperiences.) Thus, I held that a familiar face may not look—experientially—any different than itdid before, though now it looks like Joe, where before it just looked like some person. Anapparently popular response to this is to hold that something can’t come to look familiar withoutthereby coming to look different.
patient senses that something is wrong, and because the current stimulus looks just like the
familiar object but doesn’t feel familiar, the patient creates the confabulated story about
imposters, thereby explaining why someone who isn’t Mom would look like, act like, and claim
The straightforward interpretation of such cases is that the subject with the delusion
undergoes a change in overall experience, though not a change in visual experience or in visual
representations more generally. Certainly there is something introspectibly different for the
patient before and after acquiring the syndrome, but it is not at all obvious that this is a visual
difference. The patient does, after all, insist that the person looks just like Mom. This
straightforward interpretation does seem to present us with a coherent possibility: that the visual
representations are the same (i.e., have the same content) before and after the onset of the
Capgras delusion, even though the subject’s whole experience is obviously different.
Together, PK1 and PK2 argue for a theory of perceptual kinds and perceptual contents
that is liberal but not, I think, too liberal. 5. THE BOUNDARIES OF PERCEPTUAL KINDS
I have been insisting that there is a way that acids taste and a way that hands look, and so
on. However, there’s a crucial ambiguity in any such claim. If the claim is merely about the
similarity clustering among mental states, it’s relatively unproblematic; the visual state that I’m
in right now (I’m looking at my hand, the lighting conditions are normal, etc.) is
introspectively/phenomenologically significantly similar to a host of other perceptual states, and
collectively these states are introspectively/phenomenologically significantly different from other
perceptual states. But this similarity clustering is also supposed to pick out stimulus classes
(perceptual kinds), and there are some obvious difficulties determining the exact membership of
these classes, and this raises interesting problems. I say that hands look a certain way and thus
constitute a perceptual kind. But of course, some hands don’t look this way (e.g., they’re badly
disfigured or observed in bad lighting conditions), and some nonhands (e.g., movie props) do
look this way. Now what is to prevent us from saying that the relevant perceptual kind was not
hands after all, but some other class that includes some hands, but also includes things that
merely look like hands and excludes hands that don’t?
There are two problems here, one concerning false negatives and the other concerning
false positives. I’ve said that monotremes, for instance, aren’t a perceptual kind because they are
too diverse a lot. But the same could be said for any candidate kind. Hands aren’t a perceptual
kind, because some of them are so badly disfigured, they’re not recognizable as hands, some are
viewed in bad light, etc. What makes the relevant kind hands, rather than normal-hands-in-good-viewing-conditions? This is the first problem. The second is that some movie props look like
hands; so what makes the relevant kind hands, rather than hands-or-movie-props?
A quick way to solve these problems would be to hold that perceptual states represent
kinds. Hands make up a real kind; these other classes don’t. But this is not open to me, for I’ve
been insisting that perceptual kinds cross-classify things vis-a-vis natural kinds. Instead, I will
have to answer the first problem by appealing to an unfortunately undefined notion of normalcy.
Thus, I will have to say that disfigured hands are abnormal instances of hands in a way that
echidnas are not abnormal instances of monotremes. This strikes me as an intuitive claim, but it
is admittedly imprecise. I suspect that this is a fairly general problem and not just a problem for
me. Perhaps it is one that will be solved by a detailed and successful theory of content.
The second problem and its solution are a bit more interesting. Whether a group of things
constitutes a kind or not depends on what else is out there. If the birds and certain other non-
reptiles hadn’t evolved, reptiles would have made up a biological kind. Birds do make up a
biological kind, but only because, inter alia, no subsidiary branch happened to develop. Had
some of the ancestors of today’s birds given rise to a non-bird lineage, birds wouldn’t constitute a
biological kind. I want to say similar things about perceptual kinds: whether K is a perceptual
kind or not depends on what else is out there, in particular, on what else (normally) looks that
way. Water fails to be a visual kind because it’s indistinguishable from paint thinner and the
rest—not because it’s indistinguishable from XYZ. There is no XYZ, and its mere metaphysical
possibility is no more relevant to the present issue than the metaphysical possibility of non-bird
Incorporating these insights adds an interesting wrinkle. Perceptual kindhood now has to
be relativized not just to the perceiver’s perceptual apparatus and learning history, but to the
viewing conditions and environment more generally. A still hand glimpsed for a moment and/or
in bad lighting doesn’t look any different from a movie prop. But an articulated, moving hand in
good lighting conditions looks unlike any actual movie prop. So in the first case, what it looks
like is a member of the disjunctive kind; in the second case, what it looks like is a hand. The
articulated, moving thing at the end of my wrist looks like a hand, while the detached lifeless
thing under the desk over there looks like a hand-or-a-fake-hand. When animatronics reaches the
technological level that convincing, moving fake hands exist, the content of some of our visual
states will be different; things that used to look like hands (viz., hands) will then look like hands-
or-fake-hands.16 These strike me as being the intuitively correct things to say. Moreover, this
move is not merely an ad hoc attempt to wriggle out of the problem; the view follows
straightforwardly from the more general notion of kinds. All kinds are contextual in the sense
that what else is out there—in the actual world, not merely what could have been out
there—contributes to the determination of kind boundaries.
Perhaps an even stronger kind of contextualism is in order. How can my perceptual state
represent Mom, as opposed to Mom-or-her-doppelgänger? One possible answer is simply that
Mom doesn’t have a doppelgänger; if she does, then my perceptual state has the disjunctive
content after all.17 Maybe we want to say that if I’m in fake barn country, then my perceptual
states will represent barns-or-barn-facades; otherwise they will represent barns. Something like
this might even be required by any view more liberal than the noninferential theory. Something’s
looking to be a cylinder, for example, is different from its looking to be a cylinder-or-cylinder-
facade. Thus if we really want to say that something literally looks to be a cylinder even in
conditions where the subject has not directly observed the occluded sides, it is not obvious how
we can do this unless we appeal to the fact that the world—or the neighborhood—turns out not to
be rife with cylinder facades. Similarly for things that appear to be shiny, etc.
I have been trying to give a partial answer to the question of the contents of perceptual
16 This won’t be quite the same kind as the one referred to in the previous sentence as
‘hands-or-fake-hands’ since some of these don’t look at all like the articulated, moving things.
17 I mean ‘doppelgänger’ here in the old sense of a person or ghostly double, not in the
Twin Earth sense. Having a doppelgänger is thus a matter of having an Earthly double, perhapseven one that is sufficiently local and that frequents some of the same or nearby places.
states, and I have taken a phenomenological approach. My appeal to phenomenology, however,
has not been the direct sort mentioned at the beginning of the paper. The direct appeal to the
phenomenology of particular experiences amounts to the insistence that pine, e.g., seems to me to
be part of the content of my visual state rather than of some other, postperceptual state. Such an
appeal to phenomenology is typically offered in lieu of an argument, and it is always open to the
opponent to insist that it doesn’t seem so to her.
Instead, I have approached such questions indirectly, by trying to systematize more
general phenomenological considerations of perceptual similarity, which gives us a notion of
perceptual kinds. This, in turn, can be used to answer or at least constrain the answers to
questions about particular cases. The hope is that this will render direct phenomenological appeal
in particular cases unnecessary. We now have arguments about particular cases, like those
offered above concerning familiar and pine, rather than just brute appeals to intuition.
Perceptual kindhood is an extensional notion, and as such, it cannot provide full answers
to the question of how perceptual states represent the world as being. But these are exceedingly
difficult questions, and trying to give responsible answers to them quickly gets us neck deep in
other problems, such as the pragmatics of mental state ascription. We may be better off by asking
first which categories are represented in perception and using these answers to constrain our
answers to the question of which properties perceptual states represent things as having. By
constraining our answers to this latter question, attention to perceptual kindhood might allow us
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BCA-clinic Betriebs GmbH & Co. KG Dr. med. Armin Schwarzbach Facharzt für Labormedizin Zunehmende Bedeutung der Co-Infektionen bei Borreliose- Patienten - entweder paral el zu einer Borrelien Infektion oder auch anstatt - Ein Fachbeitrag von Dr. med. Armin Schwarzbach, Facharzt für Laboratoriumsmedizin Bei den Fachkongressen der vergangenen Monate ist auffäl ig, dass den Co-I
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