Epistemology of Perception, The _ Internet Encyclopedia of Philosophy

8/10/2019 Epistemology of Perception, The _ Internet Encyclopedia of Philosophy

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12/26/2014 Epi stem ol ogy of Per cepti on, The | Inter net Encycl opedi a of Phi losophy

http://www.iep.utm.edu/epis-per/

The Epistemology of Perception

Perception is a central issue in epistemology, the theory of

knowledge. At root, all our empirical knowledge is

grounded in how we see, hear, touch, smell and taste the

world around us. In section 1, a distinction is drawn

between perception that involves concepts and perception

that doesn't, and the various epistemic relations that thereare between these two types of perception are discussed--

our perceptual beliefs and our perceptual knowledge

Section 2 considers the role of causation in perception and focuses on the question of whether

perceptual experience justifies our beliefs or merely causes them. Sections 3 and 4 further

investigate the epistemic role of perception and introduce two distinct conceptions of the

architecture of our belief system: foundationalism and coherentism. It is shown how perceptual

experience and perceptual beliefs are integrated into these systems. Finally, section 5 turns to

the externalist view that thinkers need not be aware of what justifies their perceptual beliefs.

Table of Contents

1. Perception and Belief

a. Seeing That, Seeing As and Simple Seeing

b. Perceptual Beliefs

2. Perception, Justification and Causation

a. Armstrong's Causal Account of Perceptual Knowledge3. Perception and Foundationalism

a. Traditional Foundationalism

b. Sellars and the Myth of the Given

c. Concepts and Experience

d. Modest Foundationalism

4. Perception and Coherentism

a. The Basic Idea Behind Coherentism
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b. Bonjour and the Spontaneous Nature of Perceptual Beliefs

5. Externalism

6. References and Further Reading

1. Perception and Belief

a. Seeing That, Seeing As and Simple Seeing

Perception is the process by which we acquire information about the world around us using our

five senses. Consider the nature of this information. Looking out of your window, you see that

it is raining. Your perception represents the world as being like that. To perceive the world in

this way, therefore, it is required that you possess concepts, that is, ways of representing and

thinking about the world. In this case, you require the concept RAIN. Thus, seeing that your

coffee cup is yellow and that the pencil is green involves the possession of the concepts

COFFEE CUP, YELLOW, PENCIL and GREEN. Such perception is termed "perceiving that,"

and isfactive that is, it is presupposed that you perceive the world correctly. To perceive that it

is raining, it must be true that it is raining. You can also, though, perceive the world to be a

certain way and yet be mistaken. This we can call, "perceiving as," or in the usual case, "seeing

as". A stick partly submerged in water may not be bent but, nevertheless, you see it as bent

Your perception represents the stick as being a certain way, although it turns out that you are

wrong. Much of your perception, then, is representational: you take the world to be a certain

way, sometimes correctly, when you see that the world is thus and so, and sometimesincorrectly, when the world is not how you perceive it to be.

It also seems that there is a form of perception that does not require the possession of concepts

(although this claim has been questioned). It is plausible to claim that cognitively

unsophisticated creatures, those that are not seen as engaging in conceptually structured

thought, can perceive the world, and that at times wecan perceptually engage with the world in

a non-conceptual way. You can tell that the wasp senses or perceives your presence because of

its irascible behavior. When you are walking along the High Street daydreaming, you see busstops, waste bins, and your fellow pedestrians. You must see them because you do not bump

into them, but you do not see that the bus stop is blueor that a certain pedestrian is wearing

Wrangler jeans. You can, of course, come to see the street in this way if you focus on the scene

in front of you, but the claim here is that there is a coherent form of perception that does not

involve such conceptual structuring. Let us call such baseline perceptual engagement with the

world, "simple seeing". This perception involves the acquisition of perceptual information

about the world, information that enables us to visually discriminate objects and to successfully
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engage with them, but also information that does not amount to one having a conceptually

structured representation of the world. (Dretske, 1969, refers to simple seeing as "non-

epistemic" seeing, and refers to 'seeing that' as "epistemic" seeing).

You can, then, simply see the bus stop, or you can see that the bus stop is blue, or you can,

mistakenly, see the bus stop as made of sapphire. These are all forms ofperceptual experience,

ways you have of causally engaging with the world using your sensory apparatus and ways thathave a distinctive conscious or "phenomenological" dimension. Seeing in its various forms

strikes your consciousness in a certain way, a way that you are now experiencing as you look at

your computer screen. This article investigates the causal and epistemic roles of this perceptual

experience.

A little more terminology: the term "sensation" can be used to refer to the conscious aspect of

perception, but note that one can have such sensations even when one would not be said to be

perceiving the world. When hallucinating, for example, one is having the sensations usually

characteristic of perceptual experience, even though in such cases one's experience would not

be described as perceptual.

Consider how these various kinds of perceptual experience are related to our perceptual beliefs.

Perceptual beliefs are those concerning the perceptible features of our environment, and they

are beliefs that are grounded in our perceptual experience of the world. The content of such

beliefs can be acquired in other ways: You could be told that the bus stop is blue, or you could

remember that it is blue. Right now, though, waiting for the bus, you acquire this belief by

looking straight at it, and, thus, you have a perceptual belief concerning this particular fact.

Just how your perceptual beliefs are grounded in your perceptual experience is a contentious

issue. There is certainly a causal relation between the two, but some philosophers also claim

that it is perceptual experience that provides justification for our perceptual beliefs. This

foundationalist claim is denied by the coherentist (see sections 3 and 4 below).

b. Perceptual BeliefsFirst, one does not necessarily come to acquire perceptual beliefs in virtue of simply seeing the

world. Simple seeing is something that cognitively unsophisticated creatures can do, creatures

such as wasps that do not have more sophisticated beliefs, propositional beliefs. It is plausible,

though, that if one sees a certain object asa bus stop, then one would also come to believethat

there is a bus stop being seen. In many cases, this is, of course, true, but it is not in all. A

famous example is the Muller-Lyer illusion:


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The two horizontal lines above look as though they are of different lengths, the upper line being

longer than the lower. If we have seen the illusion before, then we do not believe our eyes.

Instead, we believe that the lines are the same length (which they are). Here is another case: a

habitual user of hallucinogenics may doubt the veracity of all his perceptions he may not

believe anything he sees. His perception, however, amounts to more than simply seeing he

sees the moon as being made of cheese and his cup of tea as grinning up at him. Yet, because of

the doubt fostered by his frequent hallucinations, he does not move from seeing the world as

being a certain way to believing that it is. In most cases, though, if one sees the world as being a

certain way, then one also believes that it is that way. Last, let us return to the notion of

"perceiving that." Such perception has a closer relationship with the acquisition of perceptual

belief. If one is described as perceiving that the world is a certain way, it is implied that one also

believes that the world is so. Here, there isn't room for perception to come apart from belief.

Thus, we have seen that we can be perceptually engaged with the world in various ways. Such

engagement can amount to the mere acquisition of perceptual information, the experience of

seeing the world as being a certain way, or the possession of the cognitive states of perceiving

and believing that it is so. If all goes well, such perceptual beliefs may constitute perceptual

knowledge of the world. According to the traditional account, this is when those beliefs are true

and when they are justified. Perceptual knowledge consists in knowledge of the perceptible

features of the world around us, and it is that which is grounded in our perceptual experience.

Again, the nature of this grounding is controversial. Perceptual experience is certainly causally

related to perceptual knowledge foundationalists, however, make the further claim that such

experience provides the justification that is constitutive of such knowledge (see section 3).

Others, though, including Armstrong (section 2a) and the coherentists (section 4), do not

believe perceptual experience plays this justificatory role with respect to perceptual knowledge.

The next section considers this key issue of justification.

But consider the issue of skepticism. The skeptical arguments of Descartes (1641) have had an

enormous influence on both the history and practice of epistemology. He suggests certain

scenarios that threaten to undermine all of our empirical knowledge of the world. It could be

that right now you are dreaming. If you were, everything might appear to you just as it

currently does dreams are sometimes very real. It is also possible that a powerful demon might

be deliberately deceiving you there may not be an external world at all, and all your perceptual
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experience and perceptual beliefs may be simply planted in your mind by this evil entity. Given

such scenarios, it is not clear how our perceptual beliefs can be justified and thus, how we can

have perceptual knowledge. Any reasons you have for thinking that such beliefs correctly

represent the world are undermined by the fact that you could have such beliefs even if the

external world did not exist. Since the seventeenth century, epistemology has been trying to

find a solution to this Cartesian scepticism. This article simply assumes that we can have

justification for our perceptual beliefs and that perceptual knowledge is possible. Given thisassumption, the focus is on how we should conceive of such justification.

2. Perception, Justification and Causation

Perceptual experience provides both causal and justificatory grounding for our perceptual

beliefs and for our knowledge of the passing show. In this section, we shall start to look at the

causal and justificatory relations between perception, belief and knowledge. As was discussed

above, our perceptual experience can be conceptually structured: we can see the world asbeing

a certain way, or we can see that it is thus and so. Thus, such experience could be seen as

providing justification for our perceptual knowledge in that you could be justified in taking

things to have the properties you see them as having. The fact that perceptual experience is

conceptual, however, is not sufficient to ensure that your perceptual beliefs are justified. Dave,

a friend of yours, sees every tackle made against a player of West Ham United Football Club as

a foul. He is not, however, justified in taking this to be true. Often these clashes are simply not

fouls Dave is wrong, and even when he is correct, when he really sees that a foul has been

committed, it would seem that his prejudiced observation of the game entails that in these

cases he only gets it right through luck, and thus, he is not justified in his belief. The fact, then,

that our experience is conceptual does not entail that we have justified perceptual beliefs or

knowledge. Section 3 considers what else needs to be said, and investigates an account of how

perceptual experience is seen to provide epistemic justification. First, though, consider an

account of perceptual knowledge that does not make use of the notion of justification.

a. Armstrong's Causal Account of Perceptual KnowledgeArmstrong (1961 / 1973) claims that perceptual knowledge simply requires that one's

perceptual beliefs stand in lawlike relations to the world.

What makes...a belief a case of knowledge? My suggestion is that there must be a lawlike

connection between the state of affairs Bap [that a believes p] and the state of affairs that

makes 'p' true such that, given Bap, it must be the case that p. (Armstrong, 1973, p. 75)
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Crudely, since causal relations are lawlike, if our perceptual and cognitive apparatus is such

that it is buzzing flies that cause us to have perceptual beliefs about buzzing flies, then it will be

the case that we will have perceptual knowledge of this annoying aspect of our environment

when the bees cause the belief. Armstrong calls his account a "thermometer model" of

knowledge. We can come to have knowledge of the world just as a thermometer can come to

represent its own temperature. In both systems, there is simply a lawlike relation between a

property of the world and a property of a representative device (the level of mercury in athermometer or the state of certain internal cognitive mechanisms of a thinker).

Highlighting the role of perceptual experience, Armstrong claims that:

"perception is nothing butthe acquiring of knowledge of, or, on occasions, the acquiring of

an inclination to believe in, particular facts about the physical world, by means of our

senses," (Armstrong, 1961, p. 105)

He does, however, claim that there is a "contingent connection between perception and certain

sorts of sensation," and that this, "may help to explain the special 'feel' of perception,"

(Armstrong, 1961, p. 112). Conscious sensation, then, is not essential to perception. I could be

correctly said to see the road ahead as I drive late at night on the motorway, even though I have

"switched off," and appear to be driving on "autopilot." I can see the road because I am still

causally acquiring beliefs about the world in front of me by way of my senses. Similarly, cases

of blindsight are also bonafide cases of perception. Blindsight patients claim to have a complete

lack of visual experience on, for example, their left side, yet they can make reliable reportsabout shapes and objects that are presented to this side of their perceptual field (they

themselves, however, claim that they are merely guessing). They do, then, seem to be acquiring

correct beliefs about their environment via a causal engagement between the world and their

senses, and thus, they perceive the world even though in such cases the contingent connections

with sensation are lost. Thus, on Armstrong's account, perceptual experience is not necessary

for perceptual knowledge. When one does have conscious perceptual experiences, these do not

play a justificatory role they are simply causally related to perceptual belief and knowledge.

Many, however, find such an account too sparse, in that one's experience does not play anyjustificatory or epistemic role in the acquisition of perceptual beliefs or knowledge. It is claimed

that a more satisfying theory of perception should include an account of why perceptual

experience justifies our perceptual beliefs and that we should not be content with simply an

account of why we are caused to acquire them. The following theory of perception attempts to

include just such an account of justification.

3. Perception and Foundationalism


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Foundationalists claim that the superstructure of our belief system inherits its justification

from a certain subset of perceptual beliefs upon which the rest sits. These beliefs are termed

"basic beliefs." Our belief system, then, is seen as having the architecture of a building. Later, in

section 4, we shall see that coherentists take our belief system to be more akin to an ecosystem,

with our beliefs mutually supporting each other, rather than relying for their justification on

certain crucial foundation stones. There are various versions of this foundationalist approach,

two of which are discussed in the next two sections.

a. Traditional Foundationalism

Traditionally the foundations of knowledge have been seen as infallible (they cannot be wrong),

incorrigible (they cannot be refuted), and indubitable (they cannot be doubted). For

empiricists, these foundations consist in your beliefs about your own experience. Your beliefs

are basic and non-basic. Your basic beliefs comprise such beliefs as that you are now seeing a

red shape in your visual field, let us say, and that you are aware of a pungent smell. In order to

justify your non-basic belief that Thierry Henry is the best striker in Europe, you must be able

to infer it from other beliefs, say that he has scored the most goals. The traditional

foundationalist claim, however, is that this sort of inferential justification is not required for

your basic beliefs. There may not actually be a red object in the world because you may be

hallucinating, but, nevertheless, you cannot be wrong about the fact that you now believe that

you am seeing something red. Justification for such beliefs is provided by experiential states

that are not themselves beliefs, that is, by your immediate apprehension of the content of your

sensory, perceptual experience, or what is sometimes termed, "the Given". It is, then, your

experience of seeing red that justifies your belief that you are seeing red. Such experience is

non-conceptual. It is, though, the raw material which you then go on to have conceptual

thoughts about. This conception of the relation between knowledge and experience has had a

distinguished history. It was advocated by the British empiricists--Locke, Berkeley and Hume--

and by the important modern adherents C. I. Lewis (1946) and R. Chisholm (1989). However,

this conception of how your perceptual beliefs are justified has been widely attacked, and the

next two sections address the most influential arguments against traditional foundationalism.

b. Sellars and the Myth of the Given

Sellars (1956) provides an extended critique of the notion of the Given. There are two parts to

Sellars' argument: first, he claims that knowledge is part of the "logical space of reasons" and

second, he provides an alternative account of "looks talk," or an alternative reading of such

claims as "that looks red to me," claims that traditionally have been seen as infallible and as

foundations for our perceptual knowledge. According to Sellars, no cognitive states are non-


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inferentially justified. For him:

"The essential part is that in characterising an episode or a state as that of knowing, we are

placing it in the logical space of reasons, of justifying and being able to justify what one

says." (Sellars, 1956, p. 76)

Whether we are talking about perceptual or non-perceptual knowledge, we must be able to

offer reasons for why we take such claims to be true. To even claim appropriately that I have

knowledge that I now seem to be seeing a red shape, I must be able to articulate such reasons

as, "since my eyes are working fine, and the light is good, I am right in thinking that I am

having a certain sensory experience." As Rorty (1979, chapter 4) argues, justification is

essentially a linguistic or "conversational" notion it must consist in the reasoned recognition of

why a particular belief is likely to be true or why one is rightly said to be having a certain

experience. If such an account of justification is correct, then the notion of non-inferentially

justified basic beliefs is untenable and non-conceptual perceptual experience cannot provide

the justification for our perceptual beliefs.

Surely, though, "this looks red to me," cannot be something that I can be wrong about. Such a

foundationalist claim seems to be undeniable. Sellars, however, suggests that such wording

does not indicate infallibility. One does not say, "This looks red to me," to (infallibly) report the

nature of one's experience rather, one uses such a locution in order to flag that one is unsure

whether one has correctly perceived the world.

... when I say "X looks green to me"...the fact that I make this report rather than the simple

report "X is green," indicates that certain considerations have operated to raise, so to speak

in a higher court, the question 'to endorse or not to endorse.' I may have reason to think

that X may not after all be green. (Sellars, 1956, p. 41)

Thus, Sellars provides a two-pronged attack on traditional foundationalism. The way we

describe our perceptual experience does indeed suggest that we have infallible access to certain

private experiences, private experiences that we cannot be mistaken about. However, we

should recognize the possibility that we may be being fooled by grammar here. Sellars gives analternative interpretation of such statements as, "this looks red to me," an interpretation that

does not commit one to having such a privileged epistemological access to one's perceptual

experience. Further, a conceptual analysis of "knowledge" reveals that knowledge is essentially

a rational state and, therefore, that one cannot claim to know what one has no reason for

accepting as true. Such reasons must be conceived in terms of linguistic constructions that one

can articulate, and thus, the bare presence of the Given cannot ground the knowledge we have

of our own experience or, consequently, of the world. This, then, is a rejection of the traditional


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foundationalist picture, or what Sellars calls, "the Myth of the Given."

One of the forms taken by the Myth of the Given is the idea that there is, indeed must be, a

structure of particular matter of such fact that (a) each fact can not only be noninferentially

known to be the case, but presupposes no other knowledge either of particular matters of

fact, or of general truths and (b) such that the noninferential knowledge of facts belonging

to this structure constitutes the ultimate court of appeal for all factual claims, particular and

general, about the world. (Sellars, 1956, pp. 68-9)

c. Concepts and Experience

According to traditional foundationalism, the content of perceptual experience, the Given, is

not conceptual in nature. It has been argued, however, that experience should not be seen in

this traditional way. The phenomenon of "seeing as," suggests to some that experience should

be interpreted as essentially conceptual in nature.

What is this a picture of?

You perhaps see a duck. I can, however, alter the character of your visual experience by

changing the beliefs that you have about this picture. Think RABBIT looking upward. The

picture now looks different to you even though you are seeing the same configuration of blackmarks on a white background. This picture is usually referred to as "the duck-rabbit."

Originally, you saw the drawing asa duck now you see it asa rabbit (or, as Wittgenstein would

say, you notice different "aspects" of the picture). You have, then, distinct perceptual

experiences dependent on the particular concepts "through which" you see that picture. Some

take this to prove that perceptual experience is not pre- or non-conceptual but that it is

essentially a conceptual engagement with the world. Such experience does not only consist in

our having certain retinal images: "There is more to seeing than meets the eyeball," (Hanson,


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1988, p. 294). It is, rather, the result of a necessary conceptual ordering of our perceptual

engagement with the world. This is a theory of experience that is at odds with that of the

traditional foundationalist.

The theory has Kantian roots. For Kant, one cannot experience the world without having a

conceptual structure to provide the representational properties of such experience. In Kant's

terms, the intuitions received by the sensibility cannot be isolated from the conceptualizationcarried out by the understanding. As he states, "Intuitions without concepts are blind, concepts

without intuitions are empty" (Kant, 1781, A51 / B75). Intuitions, or what we might call bare

perceptual experience--that which does not have a conceptual structure--cannot be seen as

experience ofa world, and therefore, such a conception of our perceptual engagement with the

world cannot be seen as experiential at all it is "blind". The second clause of Kant's aphorism

claims that concepts that are not based on information received through the senses can have no

empirical content. The Kantian claim, then, is that thinking about the world and experiencing it

are interdependent. This is an attack on the distinction drawn in section 1a between simple

seeing and conceptually structured forms of perception such as seeing that and seeing as. Kant

claims the notion of simple seeing is incoherent since such a non-conceptual engagement with

the world isn't experiential.

Not everyone accepts that the phenomenon of seeing as entails this picture of experience.

Dretske (1969) argues that simple or non-epistemic seeing is independent of epistemic seeing

that is, it is independent of seeing that is conceptually structured. Non-epistemic seeing

amounts to the ability to visually differentiate aspects of one's environment such as the bus

stop and the waste bin, and one can do this without seeing these items asanything in particular

(although, of course, one usually does). Further, "seeing as" presupposes simple seeing. One

has to have some bare experience to provide the raw materials for our conceptually structured

experience or thought. We may be able to see the picture above as a duck or as a rabbit, but we

can only do this if we have a non-conceptual experience of a certain configuration of black

marks on a white background. One's experience of the basic black and white lines in the figure

is independent of any concepts one may have that may then allow one to see these lines in a

certain more sophisticated way, that is, as a duck or as a rabbit. In reply, however, it could be

claimed that even such a basic experience as this relies on the contingent fact that one has the

concepts of, for example, BLACK and WHITE. Perhaps if one did not have these concepts, then

one could not even see this basic figure.

We have, then, looked at two problems faced by the traditional foundationalist, both of which

center on the alleged non-conceptual nature of perceptual experience. Two responses have

been made by those who feel the force of these objections: some modify foundationalism in


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order to take account of some of the considerations above, and others reject it altogether. The

first of these responses is the topic of the next section.

d. Modest Foundationalism

Some foundationalists agree that the Given is in some ways problematic, yet they still attempt

to maintain a "modest" or "moderate" foundationalism. Audi (2003) and Plantinga (2000)promote this view. First, our perceptual beliefs concerning both the world and our own

experience are not seen as infallible. You can believe that you see red or that you seem to see

red, yet either belief could turn out to be unjustified. Second, non-conceptual perceptual

experience does not play a justificatory role. Perceptual beliefs are simply self-justified that is,

it is reasonable to accept that they are true unlesswe have evidence to suggest that they may be

untrustworthy. Such a view of perception remains foundationalist in nature because we still

have basic beliefs, beliefs that are non-inferentially justified. Thus, the justification possessed

by perceptual beliefs is defeasible. You may, for example, have good evidence that your cup of

tea has been spiked with an hallucinogen, and, therefore, the justification for your perceptual

belief that a pig has just flown past the window is defeated. More controversially, your belief

that you seem to see red could be defeated by psychological evidence concerning your confused

or inattentive state of mind. However, in the absence of any beliefs concerning such

contravening evidence, your perceptual beliefs have prima facie justification.

Modest foundationalism avoids a dilemma that faces traditional foundationalism. It is certainly

plausible that beliefs about your own perceptual experience are infallible and that you can't be

wrong when you claim that the cup looks red. It is not clear, however, how such beliefs can

ground your perceptual knowledge since they are about your own mental states and not the

world. The fact that the cup looks red to you does of course relate to the cup, but primarily it is

a fact about how that cup strikes your experience. Recoiling from such a picture, you could

claim that your foundational beliefs concern the color of the cup and not merely your

experience of the cup. However, it is not plausible that your beliefs about the color of the cup

are infallible, and therefore, such beliefs cannot play a foundational role according to the

traditional account. The modest foundationalist can avoid this dilemma. For a perceptual belief

to be justified, it does not have to be infallible. You can, therefore, have beliefs about the

properties of objects in the world playing the requisite foundational role rather than those that

are simply about your own experiences.

4. Perception and Coherentism

Modest foundationalists attempt to keep some of the features of the traditional foundationalist


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picture while conceding that their foundations aren't infallible. There is, however, a distinct

response to the problems associated with traditional foundationalism, and that is to reject its

key feature, namely its reliance on foundational, non-inferential, basic beliefs. Coherentism

presents an alternative. Coherentists such as Bonjour (1985) and Lehrer (1990) claim that

beliefs can only be justified by other beliefs and that this is also true of our perceptual beliefs

Section 3.a described how Sellars argued for such a position in that, for him, perceptual beliefs

must be supported by beliefs about the reliability of our experience. The next two sectionsexplain the coherentist account of justifying perceptual claims.

a. The Basic Idea Behind Coherentism

For a coherentist, a particular belief is justified if one's set of beliefs is more coherent with this

belief as a member, and, conversely, a belief is unjustified if the coherence of one's set of beliefs

is increased by dropping that particular belief. The basic idea behind coherentism is that the

better a belief system "hangs together," the more coherent it is. How, though, should we

conceive of "hanging together" or "coherence"? First, one requires consistency. Our beliefs

should not clash they must not be logically inconsistent: we should not believe p and believe

that not p. However, more than mere logical consistency is required. One could imagine a set of

beliefs that consisted of the belief that 2+2=4, the belief that Cher is a great actress, and the

belief that yellow clashes with pink. Although these beliefs are logically consistent, they do not

form a particularly coherent belief set since they do not have any bearing on each other at all

For coherence, therefore, some kind of positive connection between one's beliefs is also

required. Such a positive connection is that of inference. A maximally coherent belief set is one

that is logically consistent and one within which the content of any particular belief can be

inferred from the content of certain other beliefs that one holds. Conversely, the coherence of a

set of beliefs is reduced if there are subgroups of beliefs that are inferentially isolated from the

whole.

b. Bonjour and the Spontaneous Nature of Perceptual

BeliefsFor a coherentist, perceptual beliefs are justified, as all beliefs are, if our acceptance of them

leads to an increase in the overall coherence of our belief system. An account, though, is also

required of how perceptual beliefs can be seen as correctly representing the external world, a

world that is independent of our thinking. This is particularly pressing for the coherentist

because the justification for our perceptual beliefs is provided by one's other beliefs and not by

one's perceptual experience of one's environment.


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To account for the representational ability of perceptual beliefs, Bonjour focuses upon a class of

beliefs that he calls "cognitively spontaneous." These are beliefs we simply acquire without

inference. Right now, on turning my head to the left, I spontaneously acquire the belief that the

orange stapler is in front of the blue pen, and that my glass of water is half full. These

perceptual beliefs are likely to be true when certain conditions obtain--that the light is good

and that I am not too far away from what I am looking at (these Bonjour calls the "C-

conditions"). My belief, then, that my glass is half full is only justified if I also have beliefsabout the obtaining of C-conditions. However, for Bonjour's account to be persuasive, he needs

to provide some justification for this claim that beliefs acquired in the C-conditions are likely to

be true representations of the world. This he does. First, we do not arrive at them via inference

they are spontaneous. Second, the beliefs that we acquire in this way exhibit a very high

measure of coherence and consistency with each other and with the rest of our belief system.

The question arises, then, as to why this should be so, since it is not obvious why such

spontaneous beliefs should continue to cohere so well. If, for example, these beliefs were

randomly produced by our perceptual mechanisms, then our set of beliefs would very soon be

disrupted. Bonjour's claim is that there is a good a priori explanation for the ongoing coherence

and consistency of our set of beliefs, that is, that it is the result of our beliefs being caused by a

coherent and consistent world. Thus, our perceptual beliefs correctly represent a world that is

independent of our thinking. Non-conceptual perceptual experience does not play a

justificatory role with respect to perception. This experience may cause us to acquire certain

beliefs about our environment, but the justification for these perceptual beliefs is provided by

the inferential relations that hold between these beliefs and the rest of our belief system.

There are important objections. Plantinga (1993) notes that in the Cartesian skeptical scenarios

we also have a coherent set of beliefs, but in these cases they are caused not by a coherent and

consistent world but by an evil demon or by a mad scientist who manipulates a brain that lies

in a vat of nutrient fluid (see Descartes 1641 and Putnam 1981). Bonjour's claim, however, is

that it is a priori more probable that our beliefs are not caused by these creatures. Plantinga

finds such reasoning "monumentally dubious."

Even if such a hypothesis [that concerning the claim that our coherent belief systemcorresponds to a coherent world] and these skeptical explanations do have an a priori

probability...it's surely anyone's guess what that probability might be. Assuming there is

such a thing as a priori probability, what would be the a priori probability of our having

been created by a good God who...would not deceive us? What would be the a priori

probability of our having been created by an evil demon who delights in deception? And

which, if either, would have the greater a priori probability?...how could we possibly tell?

(Plantinga, 1993, p. 109)


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5. Externalism

The varieties of foundationalism and coherentism examined so far share a certain approach to

questions concerning epistemic justification. They ask whether the evidence available to you is

sufficient to justify the beliefs that you hold. Questions of justification are approached from the

first person perspective. Foundationalists claim that you have justified perceptual beliefs

because of the fact that these beliefs are grounded in your perceptual experience, experience

that is, of course, accessible to you it is something of which you are aware, something that you

can reflect upon. Coherentists find justification in the inferential relations that hold between

your perceptual and non-perceptual beliefs, relations that are, again, something to which you

have cognitive access. Epistemic practices can, however, also be assessed from the third person

perspective. It can be asked whether a person's methods do, in fact, lead him or her to have

true beliefs about the world, whether or not such reliability is something of which they are

aware. Externalists claim that it is this perspective with which epistemology should be

concerned. A key notion for externalists is that of reliability. A belief is justified if it is acquiredusing a method that is reliable, with reliability being cashed out in terms of the probability that

one's thinking latches onto the truth.

The justificatory status of a belief is a function of the reliability of the processes that cause

it, where (as a first approximation) reliability consists in the tendency of a process to

produce beliefs that are true rather than false. (Goldman, 1979, p. 10)

One need not be able to tell by reflection alone whether or not one's thinking is reliable in the

required sense a thinker does not have to be aware of what it is that justifies his or her beliefs.

According to a reliabilist, then, a perceptual belief is justified if it is the product of reliable

perceptual processes. One strategy that reliabilists have adopted is to ground their account of

reliability in terms of the causal connections that thinkers have to the world. Roughly, for one

to have a justified perceptual belief that p, the fact that p should cause my belief that p. I am

justified in believing thatFrasier is on television because its presence on the screen causes my

belief. Such accounts are developed by Goldman (1979 / 1986) and Dretske (1981). It is

important to note the difference between this kind of account and that of Armstrong (section

2a). Armstrong eschews all talk of justification and provides a wholly causal account of

perceptual knowledge. Many externalists, however, give an account of justification in causal

terms.

It was assumed throughout this article, except during the discussion of scepticism, that we do

have perceptual knowledge of the world, and the article explored the multifarious epistemic

and causal relations that there are between the various modes of perception and perceptual


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knowledge. Justification is the key issue, and there are four basic stances. One stance is to

agree with Armstrong and deny that perceptual experience plays any justificatory role

Foundationalists see perceptual experience as the justificatory basis for perceptual knowledge,

and it is such experience that ultimately provides justification for all our knowledge of the

world. Problems with the traditional form of this position urged us to explore a more modest

form of foundationalism. Others reject foundationalism altogether. Coherentists claim that the

justification for our perceptual beliefs is a function of how well those beliefs "hang together"with the rest of our belief system. They too reject the justificatory role of perceptual experience.

Some externalists claim that justification is a matter of reliability and that so long as our

perceptual beliefs are produced by mechanisms that reliably give us true beliefs, then those

beliefs are justified. Therefore, perception is of prime epistemological importance, and it

remains the focus of lively philosophical debate.

6. References and Further ReadingArmstrong, D. M. 'The Thermometer Theory of Knowledge' in S. Bernecker & F. Dretske, eds.Knowledge

Readings in Contemporary Epistemology, Oxford University Press, Oxford, pp. 72-85, 2000. Originally

published in Armstrong, 1973, pp. 162-75, 178-83.

Armstrong, D. M.Belief, Truth and Knowledge, Cambridge University Press, Cambridge, 1973.

Armstrong, D. M.Perception and the Physical World, Routledge and Kegan Paul, London, 1961.

Included in the above is Armstrong's causal account of perception.

Audi, R. "Contemporary Modest Foundationalism," in Pojman, L. ed. The Theory of Knowledge: Classica

and Contemporary Readings, Wadsworth, Belmont, CA. 3rd edition, 2003.

A useful paper in which it is argued that modest foundationalism has advantages over traditional

foundationalism.

Bonjour, L. The Structure of Empirical Knowledge, Harvard University Press, Cambridge, Mass. 1985.

A well-developed coherentist theory of justification which includes an account of the role of perception within

such a theory. (One should note, however, that Bonjour has recently abandoned coherentism in favour of a

version of foundationalism.)

Chisholm, R. M. Theory of Knowledge, 3rd edition, Englewood Cliffs, New Jersey, 1989.

A wide ranging study of various epistemological issues including his version of traditional foundationalism.

Descartes, R. "First Meditation," inMeditations on First Philosophy, 1641. Reprinted in The Philosophica

Writings of Descartes, eds. J. Cottingham, R. Stoothoff & D. Murdoch, Cambridge University Press,

Cambridge, 1983.One of the most influential passages of epistemological writing in the history of Western philosophy in which

various skeptical possibilities are raised that suggest that our perceptual beliefs may not be justified.

Dretske, F.Seeing and Knowing, Routledge and Kegan Paul, London, 1969.

Dretske defends the claim that seeing can be seen as non-conceptual (or non-epistemic).

Dretske, F.Knowledge and the Flow of Information, MIT Press, Cambridge, Mass. 1981.

Here he presents his sophisticated version of reliabilism.

Goldman, A. I. "What is Justified Belief?," in G. Pappas, ed.Justification and Knowledge: New Studies in

Epistemology, Reidel, pp. 1-23, 1979.


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Goldman, A.I.Epistemology and Cognition, Harvard University Press, Cambridge, Mass. 1986.

In the above, Goldman forwards his reliabilist account of justification.

Grice, H. P. "The Causal Theory of Perception," in Proceedings of the Aristotelian Society, Supplementary

Volume 35, pp. 121-52, 1961.

A precursor to the various contemporary causal theories of perception, presented in the context of a sense

datum theory of perception.

Hanson, N. R. "From Patterns of Discovery," inPerception, R. Schwartz, ed. pp. 292- 305, 1988.

Hansen argues that the nature of our perceptual experience depends on the concepts we possess.

Kant, I. The Critique of Pure Reason, trans. N. Kemp Smith, 1929 edition, The Macmillan Press, Ltd.

Basingstoke, Hampshire, 1781.

One of the greatest and most influential works of modern philosophy. Of relevance to this article are Kant's

thoughts concerning the relation between our conceptual framework and the nature of our perceptua

experience.

Lehrer, K. Theory of Knowledge, Westview Press, Boulder, Colorado, 1990.

Lehrer provides a critique of foundationalism and his own developed version of coherentism.

Lewis, C. I.An Analysis of Knowledge and Evaluation, La Salle, Illinois, 1946.

Amongst various other important epistemological issues, one can find Lewis's account of traditiona

foundationalism.

McDowell, J.Mind and World, Harvard University Press, Cambridge, Mass. 1994.

In this transcription of his Locke lectures, McDowell argues that perceptual experience is essentially

conceptual in nature.

Plantinga, A. Warrant: The Current Debate , Oxford University Press, Oxford, 1993.

An excellent epistemology textbook which includes an in-depth critique of Bonjour's coherentism.

Plantinga, A. Warranted Christian Belief, Oxford University Press, Oxford, 2000.

In the context of a sophisticated discussion of the philosophy of religion, Plantinga develops a version of

modest foundationalism which he calls "reformed epistemology".

Putnam, H.Reason, Truth and History, Cambridge University Press, Cambridge, 1981.

In chapter 1, Putnam presents his contemporary brain in a vat version of the Cartesian skeptical scenario.

Rorty, R.Philosophy and the Mirror of Nature, Princetown University Press, Princetown, 1979.

A historically informed and extended attack on traditional foundationalism.

Schwartz, R.Perception, Blackwell, Oxford, 1988.

A good collection of articles focused on the epistemology of perception.

Sellars, W.Empiricism and the Philosophy of Mind. Originally published in H. Feigl and M. Scrivens, eds

Minnesota Studies in the Philosophy of Science, vol. 1, University of Minnesota Press, Minneapolis, pp

253-329, 1956. Page numbers here refer to 1997 reprint, Harvard University Press, Cambridge, Mass.

This includes Sellars' influential attack on the Given.

Author Information

Daniel O'Brien

Email: [email protected]

The University of Birmingham

U. S. A.
mailto:[email protected]

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