Images and Thinking
(Critique of arguments against images as a medium of thought)
David Cole
Page 7
This may appear to be Pinker's solution as well - except that he supposes that (if an image had an inference role) the inference role must depend upon an associated propositional label. But
all Berkeley seems to hold is that there is a purely negative restriction that is needed here - we block the inference from "this imaged triangle is isosceles" to "all triangles are isosceles" or "The Pythagorean theorem, demonstrated with this triangle, only applies only to isosceles triangles." In abstracting form the details of my concrete image, I ignore certain features of the image. In making this particular triangle stand for all, I ignore its idiosyncratic properties. This appears to fall far short of having to embed each image in a "propositional superstructure".
There is probably nothing peculiar to our use of images here. Medical students dissect cadavers. Each cadaver is representative of human anatomy in general in very many important respects, but will differ in some respects. In dissecting, med students concentrate on the general anatomical features, and abstract from eye color, fingernail length, and stomach contents.
If images have a role in thought and inference, that role must be determined by something. So far we have seen that there are problems with taking the role to be determined by the pictorial content of the image. The large question is we are considering here is whether inference role must be determined by attached propositions. Michael Tye gives a theory of images in which they are propositionally labeled data structures (1991 p 90ff). This may account for introspective reports of images in thought -- but surely the proposition is doing all the heavy lifting as far as thought is concerned! That point will discussed in conjunction with the next consideration Pinker advances against the adequacy of images as a medium of thought.
Fourth argument - image ambiguity
Pinker says that I can't represent man, the abstraction, by an image of a typical man, Fred MacMurray, because that image represents tall man, adult, human, actor, etc -- but these are all things we have no trouble distinguishing. "Pictures are ambiguous, but thoughts, virtually by definition, cannot be ambiguous." (297) (This parallels a point raised in The Language Instinct against the idea that we might think in natural language - natural language is ambiguous, thought is not. I reply to that argument in Cole 1997.) Pinker continues, "When vision leaves off and thought begins, there's no getting around the need for abstract symbols and propositions that pick out aspects of an object for the mind to manipulate."
Here I think we find clear evidence of the problem created by focussing on visual images -- and a particular subset thereof, images of non-linguistic objects. Phonological images of spoken natural language are abstract and propositional, dealing with aspects of the objects the imaged natural language sentences are about. So are visual images of written language - although it appears the latter do not play an important role in the thought of most humans (visual imagery of symbols may play an essential role in mental arithmetic, though, as in our laborious attempts at mental long division). A visual image of say a written sentence may be in a particular color on a background that may have a color, and will be a particular size, etc. Here the Berkeley strategy kicks in - none of this plays a role in inference. This abstraction from inscriptional detail is general -- the voltage with which logical "1"s are stored in computer RAM do not determine inference role (as long as they are within spec, that is, discernible by the machine), and some of the neurophysiological details of mentalese instantiations are content irrelevant and are causally inert in inference.
"[Images] cannot serve as meanings for words in the mental dictionary". Hmmm. One would hope that images are not the meanings of words -- whether in a mental dictionary, or in Webster's. We wish to talk and think about the World. We are indeed a (small) part of that world, and of disproportionate interest to ourselves, but much of our thought and talk is, and needs be, about the world around us. Thus it would be very odd indeed if say "dog" or DOG meant a mental image. The view at issue is whether images can be vehicles of thought, not the objects of thought. (They can of course, but only in arcane psychologizing.)
Pinker continues by arguing that you could not represent a negative concept, like "not a giraffe' using images. And one could not represent disjunctions, or universal propositions like "all men are mortal".
Again, these points surely hold only against pictures of extra-linguistic objects, or images that function just like pictures of objects (giraffes, e.g.) except that they are in the head. Images of extra-linguistic objects are the typical denizens of photo albums. But many of the images important for thought are not depictions of extra-linguistic objects. If thoughts run through my head, like a tune runs through my head, it will be as phonological images. Not images of noises, but of speech. These images of speech inherit the semantics of speech - and, as we have seen, such important features as compositionality, productivity and systematicity.
IV. Final Argument: The way of ideas led to a coal pit.
Reply: So it did. But only when coupled with an empiricist theory of meaning, which reduced semantics to relations between ideas. Get rid of the empiricism and anti-realism, embrace causal semantics and maybe some connectionist image processing psychology, shift attention from visual images to phonological and proprioceptive imagery of spoken language, and you have a viable alternative to mentalese theories..
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