Images and Thinking
(Critique of arguments against images as a medium of thought)
David Cole
Page 3
Presumably there may be many other kinds of mental representation beyond the four Pinker lists - there may be spatial maps, including body image, that are not visual. There appear to be representations of sequences of motor activity. These are splendidly manifest in playing musical instruments, dancing, and sub-vocalization. So it seems reasonable to hold that considerations of efficiency may count against a unified code, and further, that considerations of efficiency may not be paramount in a complex evolved system such as the brain (designed by a mindless committee, as it were, working over eons).
II. Syntactic arguments:
3. Compositionality (having a constituent structure) is essential to thought B and compositionality requires propositional reps. Images are not capable of compositionality. (see Fodor 1987 Psychosemantics: "What makes the story a Language of Thought story … is the idea that these mental states that have content also have syntactic structure -- constituent structure in particular -- that's appropriate to the content that they have." That appropriateness is cashed out as combinatorial semantics - meaning of whole is function of meaning of parts. The implication is that this consideration counts in favor of a propositional representational system, and against rivals such as images. (on the difference between prop and image, see Kosslyn 1984 Image and Brain pp. 4-5, Pinker pp. 290-293, and Tye 1991).
Reply: Two points: First, images can be compositional. The cat can be depicted worrying the rat that eats the malt that is in the house that Jack is building. One can depict a circle in a square, and then that square in a larger rectangle. If one can depict Pa Kettle standing to the right of Ma Kettle, and one can depict Ma Kettle to the right of a cow, one can combine them and depict Ma Kettle between a Pa and a cow. If one depicts the circle in the square, and in the same image depicts that square as in a rectangle, then one depicts the circle as in the rectangle. Same for other transitive spatial relations (above, left of, under).
Second, and more importantly, there appears to be presupposed what I shall argue is a false dichotomy between propositional representation system (mentalese) and imagistic representation systems. I'll discuss this more fully in responding to argument 6, the argument that representations must be capable of being true or false.
4. Productivity and systematicity are essential to thought (human thought, that is) B and images lack these features. These features set off Language of Thought theories from other forms of intentional realism (that is, theories that place meaning bearers in the head, as opposed to adverbial and eliminativist theories). The terminology is from Fodor. Productivity is the potential infinity of representations. Our "ability to understand and produce sentences…is --as I shall say -- systematic : by which I mean that the ability to produce/understand some of the sentences is intrinsically connected to the ability to produce/understand many of the others."
(Fodor 1987).
Reply: Just as they can display compositionality, images can display forms of productivity and systematicity. One can depict a circle in a square, and then that square in a larger rectangle, and go on to depict the rectangle inside an ellipse, and so forth, indefinitely, limited only by performance capacity . Visual images display systematicity when one substitutes one figure for another in an image: typically if you can depict Curly hitting Moe, and you can depict Shep, then you can depict Shep hitting Moe, and also Moe hitting Curly.
If you can depict the Parthenon against a sunny sky, and you can depict a cloudy sky, you can depict the Parthenon against a cloudy sky. One doesn’t need to think literally of art as language to note some shared traits, in particular representational flexibility, combinatorial potential and articulateness.
[And again, images of sentences will inherit all these properties, compositionality, systematicity, productivity.]
III. Semantic arguments:
5. Resemblance is an inadequate basis for semantics. If thoughts were images, thought would require resemblance semantics.
Reply: The complaint about the inadequacy of resemblance is well-taken. But, history aside, there's no reason to take resemblance as the basis of semantics for images, mental or otherwise. Images can have the same causal, indicator semantics as do (pace Fodor) the non-imagistic constituents of mentalese. This is clear even with non-mental images - a photograph of Mark is a photo of him, even though it also resembles his twin brother. It's representational qualities come from its causal history. The same can be true of mental images. My mental image of Mark is of him because it was caused by him.
Of course, photos, good photos at least, tend to resemble, in the relevant respects, the objects that cause the photographic image. And this resemblance aids us in recognition - given a photo, we can often determine who it depicts solely on the basis of internal features of the image. And then again, often we cannot. In any case, it is crucial to note this is a recognitional, epistemic role that resemblance has -- not a semantic role. What something represents and what one takes it to represent are quite different things, the first semantic, the second epistemic. The semantic relation of representation is not constituted by resemblance in the case of photos, nor is it in the case of mental images.
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