Wednesday, February 18, 2015

Rational Reconstruction
In 1976, when I delivered the John Locke Lectures at Oxford, I often spent time with Peter Strawson, and one day at lunch he made a remark I have never been able to forget. He said, "Surely half the pleasure of life is sardonic comment on the passing show".  This blog is devoted to comments, not all of them sardonic, on the passing philosophical show.
Hilary Putnam

In my post on mathematical “existence” on Dec. 13, 2014 [since then I have been posting on other topics], I summed up the difference between my previous and present views thus: In “Mathematics Without Foundations”, where I first proposed the modal logical interpretation, I claimed that conceptualism and potentialism [the position that mathematics is about the possible existence of structures, not about the actual existence of what Quine called ‘intangible objects’] are “equivalent descriptions”. In the three preceding posts I have retracted that claim.  But I don’t agree with Steven Wagner that rejecting objectualism requires one to say that sets, functions, numbers, etc., are fictions, and that the mathematics  student on the street is making a mistake when she says that there is a prime number between 17 and 34.  I now defend the view that potentialism is a rational reconstruction of our talk of “existence” in mathematics. This rational reconstruction does not “deny the existence” of sets (or, to revert to an example I used in the Dec.12 post), of “a square root of minus one”; it provides a way of construing such talk that avoids paradoxes.
In a comment (Jan. 9), Andrei Pop asked “what the objects of rational reconstruction are, if they aren’t fictions? Vague or contradictory concepts?” and I should have answered that question earlier—anyway, I will do so now!

Let us recall that for the logical empiricists (Reichenbach didn’t like to be called a “positivist” but both he and Carnap accepted “logical empiricist”), a rational reconstruction (Rationale Nachkonstuktion) was a proposal, a proposal to give a certain predicate an interpretation that exhibits the rationality of certain uses of that expression.  Reichenbach and Carnap did not understand Frege, for example, as providing a semantic analysis of the expression “natural number” (rightly not, as it happens), but as providing an interpretation of that expression that fits the work required of it in the sciences, and that avoids Frege’s “Julius Caesar” problem (the problem of providing a truth value for all expressions of the form 2=a, including ones in which a is not a mathematical term). Another example of a rational reconstruction is my account of the context-sensitivity of “knows” in “Skepticism, Stroud and the Contextuality of Knowledge” (collected in Philosophy in an Age of Science). Here the occasion for a rational reconstruction was (as I explained in another article in the same volume[1]) that

“The reason skepticism is of genuine intellectual interest—interest to the nonskeptic—is not unlike the reason that the logical paradoxes are of genuine intellectual interest: paradoxes force us to rethink and reformulate our commitments. But if the reason I undertake to show that the skeptical arguments need not be accepted is, at least in part, like the reason I undertake to avoid logical contradictions in pure mathematics (e.g., the Russell Paradox), or to find a way to talk about truth without such logical contradictions as the Liar Paradox; if my purpose is to put my own intellectual home in order, then what I need is a perspicuous representation of our talk of “knowing” that shows how it avoids the skeptical conclusion, and that my nonskeptical self can find satisfactory and convincing. (Just as a solution to the logical paradoxes does not have to convince the skeptic, or even convince all philosophers—there can be alternative ways to avoid the paradoxes—so a solution to what we may call “the skeptical paradoxes” does not have to convince the skeptic, or even convince all philosophers—perhaps here too there may be alternative solutions.) It is not a good objection to a resolution to an antinomy that the argument to the antinomy seems “perfectly intelligible,” and, indeed, proceeds from what seem to be “intuitively correct” premises, while the resolution draws on ideas (the Theory of Types, in the case of the Russell Paradox; the theory of Levels of Language in the case of the Liar Paradox -- and on much more complicated ideas than these as well, in the case of the follow-up discussions since Russell’s and Tarski’s) that are abstruse and to some extent controversial. That is the very nature of the resolution of antinomies.”

Another example: one purpose of my (and Geoffrey Hellman’s) “modal-logical” or “potentialist” interpretation of mathematics was, as I have said in these posts, to show how “Benacerraf’s Problem (and generalizations of it to non-denumerable “totalities” like the supposed totality of all sets) can be avoided.

But in none of these cases does it seem to me that one can just say that the concept in question (the concept of number, or the concept of a square root of minus one, or the concept of knowing, or the concept of truth,  or the concept of a set, is “vague or contradictory”.  Indeed, there are philosophers who don’t think these concepts (with the possible exception of “square root of minus one” in the nineteenth century) need rational reconstruction at all!   I would prefer to say that a concept needs rational reconstruction when we don’t want to simply give it up and it is problematic, and I would immediately add that whether a concept is actually “problematic” in cases like these is a philosophical question. There is no single universally agreed-on test for being problematic. Often philosophy, from Plato on, causes me to see that a concept is problematic that I had always felt I could just take for granted. 








[1] “Skepticism and Occasion-Sensitive Semantics”.

Wednesday, February 4, 2015

Message from Richard Held
In 1976, when I delivered the John Locke Lectures at Oxford, I often spent time with Peter Strawson, and one day at lunch he made a remark I have never been able to forget. He said, "Surely half the pleasure of life is sardonic comment on the passing show".  This blog is devoted to comments, not all of them sardonic, on the passing philosophical show.
Hilary Putnam

Dick Held whose experiments with kittens in 1963 and much more recent studies of human subjects who had received corneal implants (discussed in the posts that immediately precede this one, as well as in several posts last year) showed that cross-modal correlations between visual space and haptic [touch] space are learned and not innate, has made a brief but delightful comment on my argument that this fact rebuts a central argument of representationalists, viz. that the “transparency” of visual experiences—which representationalists take to be an essential and intrinsic property of those experiences—supports their theory that phenomenal content=representational content.
Here is his message in full:

Hello Hilary,
I do enjoy reading your blog and puzzling over what might be at stake if I really understood it all.  Have you ever considered the possible significance of the following:

H. Poincare

To localize an object simply means to represent to oneself the movements that would be necessary to reach it.
          
TRANSPARENT ?

Best,     Dick

    In sum, Poincare saw that visual localization is cross-modal. And, as I have been arguing,  if “transparency” involves localization (as the repeated claim that it  involves seeing qualities as “external” certainly suggests), then if localization has to be learned, transparency is not innate!


Monday, February 2, 2015

More on “Transparency”
In 1976, when I delivered the John Locke Lectures at Oxford, I often spent time with Peter Strawson, and one day at lunch he made a remark I have never been able to forget. He said, "Surely half the pleasure of life is sardonic comment on the passing show".  This blog is devoted to comments, not all of them sardonic, on the passing philosophical show.
Hilary Putnam

I have argued [see the two previous posts] that experiments performed on childred in India (the subjects’ ages ranged from 8 to 17) who had been blind from birth, but gained full sight when they received corneal implants, show that “transparency” is not intrinsic to visual experience as “representationalists” like Michael Tye claim.  Here is a passage from Tye I quoted in an earlier post (Visual experiences aren’t always transparent (8/27/2014)):

 “Focus your attention on the scene before your eyes and how things look to you.You see various objects and you see these objects by seeing their facing surfaces…intuitively, the objects you see are publicly observable physical surfaces. They are at varying angles to the line of sight and varying distances away. They can be photographed. In seeing these surfaces, you are immediately and directly aware of a whole host of qualities. You may not be able to name or describe these qualities but they look to you to qualify the surfaces. You experience them as being qualities of the surfaces. None of the qualities of which you are directly aware in seeing the various surfaces look to you to be qualities of your experiences…when you introspect your visual experience, the only particulars of which you are aware are the external ones making up the scene before your eyes. Your are not aware of those objects and a further internal object or episode. Your awareness is of the external objects and how they appear. The qualities you experience are the ones the surfaces apparently have. Your experience is thus transparent to you.”[1]

As I pointed out in my previous post (Perceptual transparency and Sinha’s observations 1/20/2015)),  if even some subjects satisfy the following description given by Ostrovsky et al (who examined the children in India immediately afer they received the corneal implants)—
“they pointed to regions of different hues and luminances as distinct objects. This approach greatly oversegmented the images and partitioned them into meaningless regions, which would be unstable across different views and uninformative regarding object identity”—
then the visual experiences of those children at those times weren’t  “transparent” to them in Tye’s sense. Afortiori, transparency is not an intrinsic property of visual experiences. It is quickly learned as cross-modal (visual-haptic[2]) connections are learned, but not innate and obviously not intrinsic. In this post, I want to consider two responses that a representationalist might make.

Response 1: restrict the claim that the objects of which viewers are immediately aware are qualities that “external” surfaces appear to have to “normal” viewers, i.e. replace “when you introspect your visual experience, the only particulars of which you are aware are the external ones making up the scene before your eyes” with “when normal viewers introspect their visual experience, the only particulars of which they are aware are the external ones making up the scene before their eyes”. Point out that until they learn to identify the objects they see, the children who received the corneal implants in Project Prakash were not normal subjects, and thus did not falsify the restricted claim.
The problem with response 1: although the restricted claim is true, it is useless for Tye’s purposes. According to Tye (loc. cit.), the unrestricted claim is explained by representationalism. Why? Because the thesis of representationalism is that the representational content of visual experiences is identical with their phenomenal character, and the representational content is about the those physical surfaces and their qualities. For the purposes of this explanation, visual experiences need to be essentially representational, and if transparency is to be an argument for that, visual experiences need to be essentially transparent, not merely transparent under normal conditions and in the case of normal viewers. This is what the studies of the Project Prakash subjects show not to be the case.
Response 2: abandon the claims that the representational content of visual experiences describes “external” objects and “physical” surfaces [but this would entail rethinking just what representationalists want to mean by “representational content”, of course], and claim merely that what are represented are qualities that the surfaces of external objects can have. This restricted claim would still entaila that even the colors that the Project Prakash subjects saw when they saw “regions of different hues and luminances” were colors that physical surfaces could have, and (according to this response) that is enough. This response concedes that “externality” may require cross-modal (visual-haptic) connections to be learned, as the experiments I have cited (including Held’s experiments with kittens in the 1960s) show, but maintains the essential thesis of representationalism, that phenomenal character=representational character.
The problem with response 2: because phenomenal character is supposed to be identical with representational character, when colors look different to different viewers, the objects they see must be repesented by their experiencs as having incompatible physical properies. According to representationalism, differences in subjective color just are differences in the objective color the viewer’s experience represents the object as having. (Note that Tye is a “color realist”.) Several kind of evidence seem to me to demolish this. Some of this is evidence “from my own case”, that I described in a previous post (Escher Colors (6/11/2014)). Another sort of evidence is beautifully described by Ned Block in “Sexism, Racism, Ageism, and the Nature of Consciousness”, a paper that shows that even normal aging affects the way colors appear to us. If my the subjective colors of the a painting on my wall is somewhat different now than it was when I was fifty, which are the true colors? Like the question, given that the subjective colors of the painting are slightly different when I close my right eye as opposed to looking at it with both eyes open, which are the true colors? the  question is absurd.

The difference between the two responses: the first response maintains the transparency claim, but limits it to “normal” people. The second response abandons it, but holds fast to the central claim of representationalism, the identity of phenomenal character and representational content. Both responses are empirically untenable.










[1] Michael Tye, “Representationalism and the Transparency of Experience”, Noรปs, 36(1), 137-151. The passage quoted is on 138-39.
[2] “Haptic” = having to do with touch.