Does the intentionalist theory of perception provide a convincing explanation of

why the argument from illusion fails? If so, what is it? If not, why not?

The argument from illusion takes roughly the following form:

i. When a person is subject to an illusion, they are aware of

something’s having a quality, F, which the actual object being

perceived does not posses.

ii. When they are aware of something’s having a quality, F, then there

must be something that the person is aware of that does possess F.

iii. As the actual object being perceived does not possess quality F,

then the person cannot be aware of the actual object after all, or

possibly they are aware of it indirectly.

iv. There is no non-arbitrary method of distinguishing between the

phenomenology of perception and illusion, at least for the perceiver.

v. Therefore, there is no reason to suppose that someone can be

directly aware of any objects even in cases of genuine perception.

The argument rests upon three assumptions. Firstly, the argument

assumes the existence of illusions, defined by Smith as ‘any perceptual situation

in which a physical object is actually perceived, but in which that object

perceptually appears other than it really is’ (2002; pp23). Secondly, it assumes

Leibnz’s law of the indicernibility of identicals; this law is relevant because the

argument describes a situation in which the ‘something’ has a perceivable quality

that the actual object does not have, and if object A has a property that object B

does not they cannot be identical. Finally, and most controversially, the

argument assumes that when it seems there is something that is F then there is

something which is F. This final assumption is called the Phenomenal Principle,

defined by Robinson as: ‘if there is sensibly appears to a subject to be something

which possesses a particular sensible quality then there is something of which

the subject is aware which does possess that sensible quality’ (1994; pp32). This

contentious principle is accepted as obvious by many philosophers such as Price

who argues that ‘When I say “this table appears brown to me” it is quite plain

that I am acquainted with an actual instance of brownness’ (1932; pp63). From

this it follows that if there actually is an instance of brownness that is being

perceived there must be caused by some object that instantiates brownness.

However, it could also be argued that in the case of an illusion the very point is

that there is no object that instantiates brownness, there is only an illusion of

brownness. This latter argument forms the basis of the intentionalist explanation

of why the argument from illusion fails.

The intentional theory of perception argues that perceptual experience

is a form of intentionality or mental representation; an intentional mental state is

one that represents something in the world. Thus the intentionalist is able to

reject the phenomenal principle outlined above. According to an intentionalist,

illusions and hallucinations are simply misrepresentations of real objects, not real

representations of ‘non-ordinary’ objects or sense-datums. Intentionalist theory

accepts that when perception is veridical or illusory the objects perceived are

real objects within the world, arguing that there are no intermediary objects of

perception. The theory does not accept that the phenomenal character of a

perceptual experience is determined, at least in part, by the real objects that are

perceived. The intentionalist must postulate that any relation to a real object in

the world is not essential to the perceptual experience; whilst states of

perception and hallucination may have the same phenomenal character and thus

be of the same mental variety, in the case of hallucination there is no real object

being perceived.

So, in order for intentionalist theory to hold, an explanation of exactly

how the phenomenal character of a perceptual experience is determined must be

given. To do this, they must first establish what perceptions and hallucinations

have in common. Intentionalists postulate that this common element is the

intentional content of the perceptual states, how the world is represented as

existing by those states. The most common approach to intentionality views

perceptual states as propositional attitudes, or sentences that take the form ‘S

___ that P’; where S refers to the subject, ___ is replaced by a psychological verb,

such as perceives or experiences, and P with a sentence. The unique feature of

these propositional attitudes is that their truth value can be determined solely

from the sentence itself. However, there are several states of mind that are not

assessable as true or false at face value; relations such as love and hate are

examples of intentional phenomena, as are non-relational states1 such as seek,

fear or expect, but none of these have propositional content. If I am hoping to

write a fantastic essay the intentional content of my hoping, or the intentional

object under a certain mode of presentation, is not something true or false.

Some philosophers such as Larson (2003) argue that all intentional

relations and intentional transitives can be reduced to propositional attitudes.

However, this hypothesis is not widely accepted, mostly because there are many

of describing perception that do not characterise its content in propositional

terms; for example, ‘Howard sees a cat in the tree’, ‘Howard notices a cat in the

tree’ and ‘Howard is watching a cat in the tree’ can all be distinguished from the

propositional ‘Howard sees that there is a cat in the tree’. In an attempt to

resolve this problem, Dretske has claimed that these semantical differences are 1Also known as intentional transitive verbs

caused by the difference between epistemic and non-epistemic seeing, but non-

propositional perceptual content is not identical to non-epistemic perceptual

content in this way. Whilst ascriptions of non-epistemic seeing are meant to be

fully extensional in their object positions, not all non-propositional descriptions of

perception need be; for example, ‘Howard saw a cat in the tree’ does not entail

‘there is a cat that Howard saw’. Nevertheless, it would seem that the ways of

describing perception used above are all elaborations upon the propositional

‘Howard sees that there is a cat in the tree’, as the momentary perceptual state2

Howard is in whilst watching or noticing the cat is one of simply seeing the cat;

watching or noticing the cat are not single perceptual states as they require

reference to other perceptual states in order to make sense. To use the examples

above, when watching the cat Howard must have been seeing it for some time,

and in the case of noticing the cat, Howard must have been seeing it for the first

time.

Separate from this issue of whether perception consists of propositional

content is whether perception is singular or general. Singular, or object

dependant, content concerns a specific object, and cannot be the content of a

perceptual experience unless that object actually exists. Singular content takes

the form of an irreducible demonstrative pronoun, ‘that G is H’. General, or object

independent, content can form the content of a perceptual experience without

requiring the existence of any particular object. General content takes the form

‘there is a G that is H’. It seems that an intentionalist must postulate that all

perceptual experiences involve solely general content, because if perception

were to be even partially object dependant the second premise of the argument

from illusion would hold.

Burge (1991) has argued that any genuine perceptual experience does

have an irreducibly singular element, despite the fact that the experience could

share an element of content with a numerically distinct experience. Furthermore,

Martin (2000) has shown that the accessibility of this hypothesis allows the

intentionalist to deny that the content of all experiences is general. For example,

suppose that experience essentially involves the exercise of recognitional

capacities and I have a capacity to recognise the prime minister. This capacity is

a general capacity that presupposes the existence of the prime minister, and it

follows from this that I am in the same intentional state when I am veridically

perceiving the prime minister as when I am hallucinating him. My capacity for

recognising the prime ministers existence depends upon his actual existence, but

not every exercise of this capacity requires his perceptual presence; the capacity

can ‘misfire’. Thus the intentionalist is able to explain how experiences can be

the same during hallucinations and veridical perceptions despite the fact that the

existence of the relevant recognitional capacity presupposes the 2Or the perceptual state Howard is in at any single specific moment

existence of the object being perceived.

Another problem for intentionalist theory concerns what exactly are the

objects of intentional states, or the intentional objects, of perceptual experience.

In terms of veridical perception the answer is clear, the intentional object is the

ordinary, mind-independent object being perceived and its properties. However,

in terms of hallucinatory perception the answer is not so clear. As the

hallucinatory experience does not involve any actual object whatsoever under

intentionalist theory, there surely cannot be any object of experience causing it.

Intentionalists postulate that perceptual experiences are representations of the

external world, but things that do not exist cannot be represented. Furthermore,

the intentionalist must explain how a representation of a non-existent pink

elephant differs from a representation of a non-existent blue swan; it is clear that

the states have different objects, but neither of these objects actually exists.

In response to this, Johnston (2004) argues that the objects of

experience during hallucinations are the properties that the hallucinated object is

perceived as possessing. In this sense intentional objects are not actual entities,

when we speak of perceptual objects we mean the word as used in phrases such

as ‘object of thought’ or ‘object of attention’ not the phrase ‘physical object’.

Intentional objects are objects from the point of view of the subject, and are not

necessarily things in reality. Thus the intentionalist does not need to commit to

the existence of real, mind-independent intentional objects and the problem is

solved.

Finally, the intentionalist must explain how the content of perceptual

experiences differs from the content of other forms of intentional state. They do

this by arguing that perception concerns non-conceptual content, the form of

mental representation involved in perception is less sophisticated in certain ways

than in cases of belief or knowledge. As belief requires conceptual capabilities

belief representation involves concepts. For example, my belief that the park is

covered in snow requires that I have the concept of a park. To put it in

epistemological terms, my belief that A is F requires that I have the concept A

and the concept F. For me to perceive that A is F does not require me to have

either concept, as my perceptual experience will represent the world as being in

a certain way regardless of whether or not I already have the concepts A and F.

However, there are many critics of intentionalist theory that find this explanation

wanting. The main objection by these critics argues that the theory does not give

an account of the qualitative or sensory character of a perceptual experience.

Unlike instances of belief or thought in general experiencing something has a

certain feeling to it. As intentionalism explains perception as a mere

representation there is no scope in the theory to explain these feelings. It is not

clear how perception is distinguished from sheer thought as representation on its

own is unable to explain the feel of a perceptual experience.

In attempt to answer this grievance, Crane (2001) argues that it is a

basic fact that perceptual intentionality possesses a qualitative character. In

accordance with this, some intentional states such as perceptions or bodily

sensations have a qualitative character whilst others, like beliefs, do not. This

argument, whilst saturated with aporia, remains intuitively strong. Block’s (1997)

solution argues that perception involves non-intentional qualia as well as

intentionality. The dispute amongst intentionalists concerning the existence of

qualia splits intentionalism into two schools; weak intentionalism accepts the

existence of quaila, strong intentionalism does not. Strong intentionalists hold

that we are never aware of qualia when we introspect our perceptual

experiences. Weak intentionalists hold that whilst this may be true, arguments

for the existence of qualia can be provided by thought experiments

To conclude, intentionalist theory is well able to explain why the

argument from illusion fails. The theory rejects the intuitively weak claim that

even during an illusion or hallucination there must be some object that is being

perceived by the subject by appealing to ideas of representation or intentionality.

Whilst this appeal throws up several problems that require further explanation, it

seems that the theory is able to deal with them acceptably; for intentionalism

retains strong intuitive value even in arguments where it is forced to appeal to

aporia.