What is the relation between perceiving the redness of a tomato
knowing that the tomato is red?


The two main issues that need to be addressed here are (a) what does it mean to "perceive" the redness of the tomato? and (b) what does it mean to "know" that the tomato is red?

As a convenient starting place, assume the traditional "Justified True Belief"definition of "knowledge".  In order for me to know that the tomato is red it must be the case that
                      (1) It is true that the tomato is red; and
                      (2) I believe that the tomato is red; and
                      (3) I am suitably justified in believing that the tomato is red.

From this preliminary understanding of what it means to "know" that the tomato is red, we can see that the relation queried in the essay title can be expanded to
                      (a) the relation between perceiving and believing that the tomato is red;
                      (b) what it is about that relation that constitutes suitable justification for the belief; and
                      (c) what function the truth has in this relation. 

Perceiving to Believing

From the internal experiential viewpoint, when I perceive the "tomato" I experience a recognizable patch of visual information (a bounded angle of view with certain spatio-temporal properties) that shares some of the visual characteristics of previously experienced things that I have learned to call "tomato".  And when I perceive that patch's "redness"I  recognize that the data-pattern in my visual field contains a property in the family of colours I have learned to call "red".  Once we start dealing with the conscious experience of perceiving the redness of the tomato we necessarily require an informationally rich context of associated beliefs.

Can I perceive the redness of the tomato without employing any of these labels or classifications?   Yes, I can -- sort of.  It is perfectly possible for me to experience a visual field (either all or part) to which I do not or cannot apply classifications and labels.  There are two ways that this can happen.  I can be distracted from consciously attending to my visual field (or part thereof).  Or my visual field can contain "data patterns" that defy classification on my part. 

If I am distracted from attending to part of my visual field, I might be receiving the photons from the tomato, and doing some processing in my visual cortex.  But the information is not making it to my conscious awareness.  Classifying and labelling the visual data-patterns that pass before me is not an automatic and immediate process.  It demands a conscious focus of attention.  As I gaze out the window, deep in thought, my eyes pass over a scene that contains numerous familiar visual data-patterns.  When I attend to what I am looking at, I can identify (classify) what it is I am seeing.  But when I am pondering the answer to the essay question, I am distracted, and do not consciously attend to the visual data before me. 

In the normal course of events, when I am consciously attending to some part of my visual field, I am actively classifying and labelling whatever it is I focus my attention on.  Unless, of course, my visual field contains "data patterns" that I cannot match with any of my classifications.  In such cases I will usually make a classification error -- classifying what I see as, for example, a "pepper" instead of a "tomato" (assuming I don't know what a tomato looks like), or the tomato's colour as "rose" instead of "red" (assuming I don't know what red looks like).

So, for me to perceive the redness of the tomato, I must experience and consciously attend to a visual field containing a "data pattern" that I can classify as a "tomato" and as "red".  Once I have classified the data-pattern, I can form the belief "the tomato is red" to capture my visual experience.  This last step is also an active effort of consciousness.  I can gaze out my window and land my focus on various things (data-patterns I classify) without forming any propositional beliefs about what I am seeing.  I only form a propositional belief when I need the information for some purpose -- even if it is only the saying to myself what it is I am looking at.  The belief that "the tomato is red" is only one of very many possible beliefs I might form, given the perception of a red tomato.  The visual field presents data patterns that are far more rich than can be expressed in a simple proposition.  I only form a belief about the tomato being red if I have some need for that information.  I might just as easily form the belief that the tomato has a blotch on it, or the tomato is sitting on a book, or there is something to eat, and so forth.

Believing to Knowing

To discover what it is about that the relation between perception and belief that constitutes "suitable justification" for the belief we need to delve a little more deeply into how "suitable justification" qualifies a "mere" belief for the honorific of "knowledge". 

Different theories of knowledge define "suitable justification" in different ways.  Therefore, what will constitute "suitable justification" will vary according to the theory of knowledge applied.  The coherence theory, as an example of an internalist understanding of justification, would maintain that my belief that the tomato is red qualifies as knowledge if and only if such a belief coheres with (and maximizes the coherence of) the rest of my beliefs. 

Coherence theorists generally describe the coherence involved as "explanatory" coherence.  Knowledge gained as a consequence of the explanatory coherence of our belief about "the redness of the tomato" with the rest of our beliefs set can therefore be considered as justified based on "inference to the best explanation".  The best explanation is more coherent the more beliefs it incorporates into the network, the greater the range of beliefs it records, explains, and allows us to anticipate.  A belief-system is more coherent the fewer self-contained sub-sets it contains, and the fewer beliefs it dumps into the irrelevant category.  Coherence of the best explanation is also increased by our epistemological self-understanding.  Beliefs about our belief forming processes, and our standards of what constitutes the "best" explanation, are important contributors to the explanatory coherence of our belief-set.

However, coherentism does not grant any special status to perceptual beliefs.  The coherence account of knowledge therefore does not provide any specific linkage between one's network of beliefs and that "truth" we identified earlier.  There is nothing within an "inference to the best explanation" that necessarily connects our belief that the tomato is red with the actual redness of the tomato.  Without granting some special status to perceptual beliefs, it is difficult to find a way to ensure that one's coherent set of beliefs maintains some sort of linkage to reality.  It is always at least logically possible that there is more than one coherent set of beliefs that might be equally "best" explanations of the known evidence.  Therefore, "inference to the best explanation" is not sufficient to ground our knowledge of the redness of that tomato.  There must be some allowance made for a connection to reality.  And that is the function of perceptual beliefs.  Perceiving the redness, however understood, has to have sufficient weight to ground a uniquely "best" explanation.

The Contextual theory of knowledge combines the best of coherentism with some reliablism and an acknowledgement that beliefs based on perception require a special status.  Contextualism also has an additional benefit to recommend it.  All of the other JTB theories understand "suitable justification" as meaning that the subject must have adequate grounds to support the claim to knowledge prior to the claim.  Contextualism adopts instead the "default and challenge" model of justification, maintaining that if it seems to me that the tomato is red then that is prima facie suitable justification for my knowing that the tomato is red.  The "prima facie" conditional is required, of course, in order to rule out the possibility that I might be aware of circumstances that would render dubious the veracity of how things seem to me.

The Role of Truth

And this brings us to the role that the truth of the matter plays in perceiving the redness of the tomato.  There are three different "theories of perception" that grapple with this issue.

The direct realist theory of perception is "realist" because it maintains that the objects (like tomatoes) we perceive normally exist and maintain most of the properties we perceive them as having (like redness) even when they are unperceived.  The theory is "direct" because it maintains that we are directly and immediately aware of the existence and nature of physical objects in our environment and their properties.  (This is not to suggest, as direct realism is often accused of suggesting, that its redness is necessarily an intrinsic property of the tomato.  Direct realism maintains rather that the tomato has an intrinsic property that a normal perceiver will see as "red" under normal perceiving conditions.)   Direct realism maintains that the there is an evidence transcendent truth that counts.  And hence that perceiving the redness of the tomato is becoming consciously aware of the evidence that the tomato is red.

The indirect realist theory of perception agrees with the direct realist that we are aware of the existence and nature of physical objects in our environment, and that the objects we perceive normally exist even when they are unperceived.  Where the indirect realist differs is in maintaining that we do not gain this awareness directly, but only in virtue of a direct perception of some intermediary -- called variously a "sensation", "appearance", "sensum", "percept", or "representation", or (in its more popular form) "sense data".  If indirect theories of perception are right, then there is something between the tomato and the conscious "I" that becomes aware of the redness of the tomato.  That thing is the "sensation" or "sense-data" of the tomato.  The sense-data is invested with all of the properties possessed by the appearance of the tomato (such as its redness), and it is those properties that we actually perceive.  Somehow, somewhere between the real tomato and our conscious awareness some intermediate medium or our sensory input processors "translate" the actual straightness of the stick in the water glass into a bent appearance, or the actual round shape of the table into an oval appearance, or thin air into a pink elephant appearance, or the unknowable "nuominal" nature of the tomato into the perceived "phenomenal" properties of the tomato.

However, indirect theories of perception are fatally flawed.  First of all, the sense-data theories assume that if the tomato appears to have redness, there must exist something that intrinsically has redness.  But there is no need to reify appearances.  If a church looks like a barn, we do not perceive a barn appearance.  We perceive a church that looks like a barn.  Secondly, if the tomato's sense-data do have the properties they appear to have (which, according to the theory they must), where and what are these sense-data?   They are certainly not physical objects located in physical space in the place that they appear to be located.  Of course, they may be simply encoded representations of the tomato's appearance -- brain-states of encoded neural network impulse strings, perhaps.  But if that is the case, in what sense can the sense-data be said to "have" the redness they are supposed to have?   And in what sense would a conscious appreciation of that encoded representation differ from a direct perception of the tomato?   Thirdly, indirect realist theories presume a hidden Cartesian Dualism.  Such theories demand somewhere in the consciousness/mind/brain a place where sense-data ("appearances") can be "presented" for our consciousness to "appreciate" and evaluate.  They assume, therefore, some manner of direct perception by the consciousness of the presentation.  But in the absence of mind-brain dualism, if the mind's "appreciation" of the sense-data is necessarily direct, then why can't the mind's appreciation of the tomato itself be direct?

Which brings me to the third family of theories of perception.  Phenominalism agrees with the indirect realist that the mind is not directly aware of the objects of perception, but only aware of the experiences of perception.  On the other hand, phenominalism agrees with the direct realist in maintaining that the mind's appreciation of those experiences is direct and not mediated by "sense data".  Where the phenominalist differs from the two is in maintaining that there is nothing beyond, behind, or underlying, those perceptual experiences.  All there is, is the experience of redness, the experience of the tomato.  All the tomato is, is a series of experiences.  However, in order to avoid collapsing into Solipsism, Phenominalism demands the additional "free-floating"( unsupported) premise that there are in objective fact other people out there that are the basis (the behind, the underlying) of our experiences of other people.  So a non-Solipsistic Phenominalism is fundamentally self-contradictory.


The relation between perceiving the redness of the tomato and the belief that the tomato is red consists of three parts -- (i) a consciously attended to experience of a visual field containing a data-pattern that can be classified as a tomato and as red; and (ii) the conscious recognition of similarities between this and past experiences and the classification of the data-pattern as "a tomato" and "red"; and (iii) the forming of a belief expressing that classification as directed by some informational need.

By adopting a Contextualist variant of the Justified True Belief definition of knowledge we can maintain that our belief that the tomato is red is prima facie sufficient justification for our knowing that the tomato is red.  Our perception based belief that the tomato is red must cohere with (and maximize the coherence of) the contextually relevant sub-set of our entire belief-set.  And that contextually relevant sub-set, it should be restated, will include any beliefs about the normality of the seeing conditions, the reliability of our perceptual belief-forming processes, the boundaries of our conceptual classification schemes, the meaning of any labels we employ, and the informational need that drives the belief formation process.  Contra foundationalism, those contextually relevant other beliefs are necessary in order to form a perpetual belief.  Contra coherentism, "inference to the best explanation" is not sufficient to ground perceptual beliefs.  A connection to the truth of the matter is necessary if we are to maintain any hold on reality.

Finally, by adopting a Direct Realist approach to perception we can maintain that the truth does matter.  There necessarily must exist within our visual field a tomato that is in fact red in order that we may perceive the redness of the tomato.  Perceiving the redness of the tomato is direct and immediate awareness, and hence suitable grounds for believing that the tomato is red, and prima facie justification for knowing that the tomato is red.

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