Wednesday, March 21, 2007

Is Perception Always Experiential? (by guest blogger Joshua Rust)

In an earlier post, Eric asked the question, "Is There an Experience of Thinking?". In this post I would like to look at a related question—is perception always experiential?

Given the amount of philosophical ink spilled on this question, I think it will be more helpful to proceed indirectly by reframing it as an interpretive question.

First, some background: if the question concerns the role phenomenal properties play in perception, there are two broad classes of answer. On one hand, phenomenalists argue that phenomenal properties are necessary for perception (Chalmers, Pitt, Siewert, G. Strawson). On the other hand, representationalists argue that a phenomenal experience is not necessary for sensory experience (Dennett, Brandom, McDowell, Rey, Sellars), or else is reducible to perception's intentional content (Dretske, Lycan, Tye). For more background see Pitt's excellent entry on mental representation in the Stanford Encyclopedia of Philosophy (especially sections 3-5).

Now, the interpretive puzzle: Pitt includes John Searle within the phenomenal camp. He claims that Searle thinks that phenomenal properties are necessary in determining the content of sensory experience. While there is much in Searle which supports Pitt's characterization of Searle, I have recently come across a passage in Intentionality which suggests Searle's considered view is otherwise: while phenomenal conscious properties are "characteristic" of perception, for Searle, they are not necessary.

Searle is clear that beliefs need not have phenomenal experience. But perceptions are different: (A) "States such as beliefs and desires need not be conscious states. A person can have a belief or desire even when he is not thinking about it and he can be truly said to have such states even when asleep. But visual and other sorts of perceptual experiences are conscious mental events" (Intentionality, 45).

He then goes on to assert that, (B) "Someone who claimed that there was a class of beings capable of perceiving optically, that is, beings capable of visual perception but who did not have visual experiences, would be making a genuine empirical claim" (Intentionality, 46).

Given what he says in (B), one would expect that Searle would then cite empirical evidence which would buttress his claim in (A), that in order to percieve one must have some sort of conscious, phenomenal experience. He does go onto cite empirical evidence, but it doesn't appear to justify the claim made in (A).

(C) "Weiskrantz, Warrington and their colleagues have studied how certain sorts of brain lesions produce what they call 'blind sight'. The patient can give correct answers to questions about visual events and objects that he is presented with, but he claims to have no visual awareness of these objects and events. Now, from our point of view the interest of such cases derives from the fact that the optical stimuli the patient is subjected to apparently produce a form of Intentionality. Otherwise, the patient would not be able to report the visual events in question. But the Intentional content produced by their optical stimulation is not realized in the way that our presentational contents are realized. For us to see an object, we have to have visual experiences of a certain sort. But, assuming Weiskrantz's account is correct, the patient can in some sense 'see' an object even though he does not have the relevant visual experiences. He simply reports a "feeling" that something is there, or makes a "guess" that it is there. Those who doubt the existence of visual experiences, by the way, might want to ask themselves what it is that we have that such patients seem to lack" (Intentionality, 47)

To my ear, Searle appears to misconstrue the significance of the 'blind sight' evidence. If blind sight tests show that we can see without having certain phenomenal experiences (C), given that Searle holds that phenomenal experiences must be present in order to see is an empirical claim (B), then the blind sight test seems to contradict his claim in (A) that perceptual experience is a conscious mental event.

Questions: are there are alternative readings of these passages which saves Searle from incoherence? Given (C), is Pitt wrong to characterize Searle as a phenomenalist about visual experience in the SEP article? More generally, is a phenomenal experience necessary for perception? If so, is there any way for the phenomenalist to make sense of the Weiskrantz "blind sight" findings?

7 comments:

michael metzler said...

Joshua,

This was a helpful post. I stopped reading Intentionality at page 37 a couple weeks ago, and given my purposes I now see that I shouldn’t have!

I think there might be way to save Searle from incoherence; in fact, I think this section, read in context of Chapter 7 of Searle’s The Rediscovery of Mind, reveals a natural coherence . . .if it were not for his claim that there was “some form of intentionality” involved in the case of ‘blind site’. That is the one phrase I don’t necessarily get; but perhaps there is a solution to this too:

For Searle, I think the difference between “see” and “ ‘see’ “ is what would make the difference here. This would seem to be a “mere ‘as if’” seeing, not a literal seeing. This ‘seeing’ is really more like a “feeling” than literal perception. As is seen in other discussions of ‘blind site’, the need to actually make “guesses” in order to report the possessed information is crucial; it is notable, then, that “guess” is the next word that Searle makes explicit note of. I would therefore take Searle as coherent here, and his statement “even though he does not have the relevant visual experiences” as meaning that by definition the ‘blind site’ patient does not literally see, regardless of the odd “feeling” that enables to patient to “guess” when prodded by certain questions. No?

But then, why does Searle seem to suggest that there really is a literal “form” of intentionality going on here if understood to come BEFORE the reporting? But perhaps this is ambiguous; perhaps Searle means that the reporting is what brings in a form of intentionality in an ad hoc way?

michael metzler said...

...I went back once again to the passage: only "apparently" is there a form of intentionality involved with 'blind site'. So currently I'm a defender of Searle's full coherence. . . and only coherence.

Joshua said...

Michael--your post has been very helpful in disentangling Searle's view. Perceptual experiences--unlike beliefs--must be conscious, for Searle. He bites the bullet: blind sight isn't conscious so it can't be a case of perception. (Searle: "the Intentional content produced by their optical stimulation is not realized in the way that our presentational contents are realized.").
What is it then? You suggested that it isn't a case of intentionality at all (although it can be described in intentional terms). Another possibility is that the experience is more akin to belief than perception. Beliefs need not be conscious. To the extent that beliefs are like "guesses", this reading is substantiated. It moreover would explain what Searle means when he writes that the "optical stimuli the patient is subjected to apparently produce a form of Intentionality" (although you are right to draw attention to the "apparently"). Blind sight is more a belief-like rather than a perceptual form of intentionality.
Here's one difficulty: an important difference between the intentional forms of belief and perception is that the latter, on Searle's view, is "causally self-referential"--it must be brought about by its object. I don't know much about blind sight cases, but imagine that the subject could "guess" when a certain object is in front of him with the same reliability of someone who regularly perceives the object. In both cases, we would say that it is the object which causes the intentional experience. And since both blind sight and perception seem causally linked to their object (they are causally self-referential), doesn't blind sight seem more akin to perception than belief? Why require conscious experience when blind sight is, in every other respect, totally akin to regular perception?

michael metzler said...

Joshua,

Thanks for the reply! Good stuff. It is not clear to me how Searle is biting the bullet in his response to blind site. If the only element missing in blind site was the conscious experience, I think I could see the point (this seems to in fact be your concluding point); but I do not think this is the case. I doubt Searle would want to say that beliefs are like guesses, and in the blind site case, it seems generally agreed (from the little I’ve seen) that the blind site patient does not have anything like beliefs about the information relevant to the blind sector of the visual field; this is what seems particularly fascinating to me about blind site: the information is accessible but only in a very round about way; the patients would never produce the information on their own, and they have no dispositions to assert anything about the information until they are prodded with particular questions. And even then, it comes in the form of guesses and not judgments. Searle would probably grant that there is much non-conscious information available to the body and brain – but he relegates these as part of the “external” world. Mere optical stimulation and some sort of resulting information storage, it seems, just not going to give us the natural, literal use of “seeing”, which seems to be what counts as “perceiving”.

On the suggestion that blind site is akin to beliefs: This seems to be what Searle is committed to denying: anything not in the domain of occurent consciousness is considered non-conscious, rather than unconscious, and possesses no literal intentionality, unless a specific reason can be given for treating the state as holding a special sort of relationship to conscious intentionality. In the case of beliefs, it is their preservation of ‘aspectual shape’ and their capacity to produce conscious states with intrinsic intentionality. With blind site, the only connection to intrinsic, conscious intentionality is manipulated guessing, which requires additional environmental stimuli and the resulting conscious deliberation of the patient; so it doesn’t seem that what the patient “has”, or the experience undergone, provides the right sort of connection.

As to the suggestion that ‘blind site’ (on redefinition) is akin to perception: I would think that the object’s indirectly bringing about the guessing is not going to be sufficient. On Searle’s view, what characterizes perception just is the distinct way the intentionality is realized; this just is what makes perception ‘presentation’ rather than ‘representation’: its “directness, immediacy and involuntariness”. Blind site seems to me more akin to perception with respect to the source of information, but not, on Searle’s view, akin to what brings in the “form” of intentionality (which would be the guessing).

I didn’t think I would be defending Searle anytime soon! Again, I am only attempting a defense of Searle’s coherence. . . .

Anibal said...

Searle made recently the review of Humphrey´s new book entitled "Seeing Red", and there Humphrey distinghises, following Thomas Reid, a duality in psychological states.
He differentiates between "visual perception" and "visual sensation" not too much surprise because is a consequence of extending his amazing discoveries relating to "blind sight" phenomena.

In my view Searle and Humphrey´s point of views are apart in this respect. While in Searle intentionality and consciousness goes hand in hand neglecting Freud´s overtone concept of unconsciosness; Humphrey looks with sympathy a duality in visual perception and visual sensation with the self entering the scene after.

To me the phenomenalist is loosing the debate at least due to the actual trend in cognitive science in general, where the unconscious or the non-concious is growing in acceptance from neuroscience to the psychology of automatic behaviour permeating all branches.

Joshua said...

Michael- again, you've made some really insightful comments. I think you are right to emphasize the disanalogies between blind-sight-as-guessing on the one hand and belief and perception on the other hand. According to Searle's "connection principle," in order for something to count as even unconscious it must be potentially conscious. While blind sight patients accurately guess what the stimuli was, it is also clear that this guess doesn't involve an uncovering of a previously masked conscious state. There is no conscious, perceptual state which is even in principle available to the blind sight patient, so whatever blind sight is it can't be a conscious. As you put it--it has no aspectual shape.
I'm beginning to buy your reading of Searle's take on the blind sight case.

Just to play devil's advocate in favor of a reading of Searle which sees blind sight as a kind of intentional state: What if, upon being asked, the blind sight patients reported that their "guess" was prompted by a "feeling". Couldn't that feeling, however degenerate, be construed as the aspectual shape which must accompany all forms of intentionality. You are right to say that the brain receives much non-intentional information which then results in behavior; but if this information comes to represent itself and its causes propositionally (even by way of a guess), wouldn't *that* information be better characterized as form of intentionality?

If I've been resisting your reading of Searle's reading of the blind sight scenario, it principally because I don't think that conscious experience must be (even in principle) necessary for something to count as a perception. So, at least in certain cases, I'm tempted to count blind sight as genuinely perceptual. But as far as Searle's views are concerned, given the centrality conscious experience in the attribution of intentionality, Searle recognizes the logical consequences of his view in precluding blind sight from the sphere of the perceptual. (it was my own view that makes me feel like Searle was "bitting the bullet" in precluding the blind sight cases).

Again, thanks for the stimulating conversation!

michael metzler said...

Joshua,

This discussion has been helpful for me too! Yes, I’m with you in rejecting all the restraints Searle has for intentionality. Yet, I’m still a bit skeptical that the blind site case gives much ammunition for the cause. This is because it seems to me, at least on the face of it, that there is a big enough difference between what I think both you and I might want to call normal unconscious perception and what is going on in the case of blind site. I’m actually hoping to find some literature giving empirical findings to the fact that we normally have better and different conscious access to information via unconscious perception than we do in the case of blind site.

But I like your noting of the “feeling” Searle mentions. I did not even think of that part of the story. I need some further distinctions before I would be confident with what to do with that. We have the additional stimulus from the questioner, the feeling, the propositional guess, etc. It seems we need to fill out the story about how all this comes together; e.g. is this feeling just the phenomenal side of thinking the thought (Pitt) that generates the linguistic guess? My guess (!) is that the additional stimulus of a question directly causes the beginning of the patient’s intentional search for the best answer. Whatever information-memory is left in the brain (or even still within the original sensory module?) due to retinal stimulation that explains statistically correct guesses is not what we could consider a normal cause for the resulting propositional guess (although keep in mind I am no expert on real blind site either). And if we ask Searle, he would say that the residing information from retinal stimulation has to be the sort of state that has the capacity to cause the phenomenal guess, or at least just that aspectual shape of the “feeling”. But it just isn’t clear to me that this is the sort of ‘state’ that we are dealing with in the case of blind site.

But I really would be interested to see how you would respond to these further considerations; if we could say that the retinal stimulation is a robust form of ‘seeing’ I think that would be cool.

However, if I’m right that blind site isn’t the best form of ammunition, what is? I think the crux might be located at the distinction between literal/metaphorical. I’m inclined to think that our references to unconscious perception (like the kind of propositional information you describe) are metaphorical, in the same way our talk about the beliefs of someone sleeping is, yet still explanatory. I do agree with Searle that the meaning of ‘perceive’ and ‘see’ is rooted in our conscious seeing; I just disagree with what that implies about the unconscious mind. I like anibal's last comment in this regard.

Thank you for following along this far!