Imagery and Imagination
Amy Kind
Page 1
Source: http://www.iep.utm.edu/imagery/
Both imagery and imagination play an important part in our mental lives. This article, which has three main sections, discusses both of these phenomena, and the connection between them. The first part discusses mental images and, in particular, the dispute about their representational nature that has become known as the imagery debate. The second part turns to the faculty of the imagination, discussing the long philosophical tradition linking mental imagery and the imagination—a tradition that came under attack in the early part of the twentieth century with the rise of behaviorism. Finally, the third part of this article examines modal epistemology, where the imagination has been thought to serve an important philosophical function, namely, as a guide to possibility.
1. The Imagery Debate
Consider the following list of questions:
- What shape are a beagle’s ears?
- How many windows are in your bedroom?
- Which is a darker shade of green, a pine tree or a frozen pea?
- When a person stands up straight, which is higher, her navel or her wrist?
- If the letter D is turned on its back and put on top of a J, what does the combination remind you of?
When attempting to answer these questions, which are adapted from Pinker (1997) and Kosslyn (1995), you undoubtedly produced mental imagery—images of beagles, of windows, and of peas. For some of these questions, you probably had to produce two different images to compare to one another, while for some of the other questions, you probably had to rotate the image you produced from the orientation at which it started. These tasks probably also seemed routine—the production and manipulation of mental images are common aspects of our mental lives. But what are these mental images? What role do they play in our mental life? In attempting to answer these questions, philosophers and cognitive scientists have given two very different sorts of answer.
a. Two Views About Mental Images: Pictorialism vs. Descriptionalism
We are naturally inclined to think of mental images as analogous to non-mental images. Consider, for example, my mental image of the Grand Canyon and a photograph of the Grand Canyon. Intuitively, the two are similar sorts of representations. Both are pictures—only the latter is in a frame while the former is in my head.
This view of mental images, commonly referred to as pictorialism, is defended most prominently by Fodor (1975) and Kosslyn (1980). (See also Kosslyn and Pomerantz 1977.) In addition to its intuitive attractiveness, pictorialism derives support from various empirical experiments concerning mental image rotation and scanning (Shepard and Metzler 1971; Kosslyn 1973; Shepard and Cooper 1982). In one such experiment, subjects were asked to identify whether a pair of figures, such as letters, digits, or block formations, were identical or different. In each pair, the second figure had been rotated to an orientation different from the first. The experimenters discovered that subjects’ response times varied directly with the degree of rotation between the figures, a finding that suggests that the subjects were mentally rotating images of the objects.
Despite this intuitive and empirical support, however, pictorialism runs into trouble in its attempt to account for the mental pictures (or, at least, the quasi-pictures—see Kosslyn 1980) that it posits. If such pictures are non-physical, then they are not made of the right sort of “stuff” for use in a scientific conception of the mind. In order to avoid dualism, then, the pictorialist seems forced to suppose that these pictures in the head are located in the brain. Unfortunately, this supposition is also problematic, as it is not clear that there are any structures in the brain that could plausibly be construed as these physical pictures.
Motivated in large part by such worries, many philosophers and other researchers in contemporary cognitive science advocate an alternative view called descriptionalism. Among its most prominent defenders are Dennett (1969, 1979) and Pylyshyn (1973, 1978). While pictorialists claim that mental images represent roughly in the way that pictures represent, descriptionalists claim that they represent roughly in the way that language represents. Consider a state of affairs where George W. Bush is seated to the right of Dick Cheney. One way to represent this situation is by drawing a picture of Bush and Cheney with Bush sitting to Cheney’s right. As we have seen, pictorialists claim that this provides us with a model for the way that mental images represent. But another way to represent the same state of affairs is with a sentence such as, “George W. Bush is sitting to the right of Dick Cheney.” Descriptionalists claim that this provides a better model for the way that mental images represent.
Natural language descriptions, however, are by no means the only kind of representations that count as descriptional in the sense intended by descriptionalists. In fact, for the descriptionalists, a representation can count as descriptional even if it is not literally descriptive of the states of affairs represented. Consider one such representation: the binary language of a computer. In a computational system, a particular string of 0s and 1s might represent the above state of affairs. Alternatively, consider a representation of this state of affairs that proceeds by defining a certain operator, the “RIGHT-OF” operator, that takes an ordered argument pair: RIGHT-OF(George W. Bush, Dick Cheney). Like the sentence “George W. Bush is sitting to the right of Dick Cheney,” the binary representation and the operator representation are clearly not pictorial in nature. One important reason is that these representations do not look like what they represent. What sets pictorial representations apart from other representations is that they represent in virtue of having at least one visual characteristic (e.g., form, shape, or color) in common with what they represent. So, for example, though a black-and-white photograph can represent a pumpkin pictorially, a drawing of a purple triangle cannot.
The dispute between the pictorialists and the descriptionalists, known as the imagery debate, has generated considerable controversy and discussion in the last thirty years. As we have seen, the imagery debate concerns the representative nature of mental images. The descriptionalists challenge the pictorialists’ claim that mental images represent in a pictorial way. Unfortunately, the imagery debate is commonly mischaracterized as a debate over the existence of mental images. Descriptionalists are often taken to be denying the existence of mental images, while pictorialists are often taken to be defending their existence. (See Block 1981a for discussion of this mischaracterization.) The situation is exacerbated by the very participants in the debate, who themselves often obfuscate the issue between them. Dennett (1979) describes the debate as “a war between the believers and the skeptics, the lovers of mental images … and those who decry or deny them,” and he frequently puts his own position in terms of “abandoning” mental images. Likewise, Fodor (1975) cites empirical studies in an effort to “argue forcibly for the psychological reality of images.” The pictorialist, however, should really be seen as arguing for the psychological reality of pictorial representation, which is also what the descriptionalist should be seen as abandoning.
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