Descriptivism and Standard Objections to Mental Images

Descriptivism relies on a set objections to mental imagery that have become more or less standard in contemporary philosophy. These objections derive from an analysis of thought that emphasizes the importance of linguistic structures and linguistic elements. Essentially, these objections are based on the idea that we should characterize our mental processes (particularly thought processes) as forms of "inner speech" rather than ways of using mental images.

Three Objections

There are at least three important descriptivist objections.

1. NO IMAGES FOR ESSENTIAL CONCEPTS

This objection dates far back in the history of philosophy. Plato and Aristotle were aware of this objection (though they are both usually classified as Imagists). In this century, the basic objection has become one of the mainstays of the descriptivist position. The basic objection attempts to demonstrate that

IMAGES CANNOT BE ESSENTIAL OF HIGHER-ORDER THOUGHT PROCESSES.

Blanshard's (The Nature of Thought ,1940) provides an excellent example of how this position is supported. Blanshard pointed out that that there are many important classes of ideas for which there are evidently no images at all. There are no apparent images, for example, for non-sensible individuals such as "self" or "substance." Nor are there images for relations between objects (on, next to, part of). Another example: there is no image of the relation of causality. As Hume noted, this is a primary relation between things through which we structure our thinking.

Furthermore, there are no images for the logical relations and quantifies (and, or, not, some, all), and these are clearly essential to thought. Finally, images do not seem to be capable of serving as signifying universals or general ideas. Contrary to what Locke (an Imagist) seems to have held, if we think of the general idea of a triangle, we find that we can only form an image of a particular kind of triangle -- a scalene or right triangle. There is no image for "triangles in general." In sum, descriptivists object that since there are no images for the fundamental ideas that are the basis for structured thought, images clearly have very little to do with thought.

Contemporary descriptivists nearly always make similar points in defense of their view.

2. NO CONTENT OBJECTION

This objection points to the fact that images do not have any intrinsic meaning. Wittgenstein's famous example is a sketch of a man on an incline. Is the man going up or sliding down? The image itself gives no clue. It is up to us to provide an interpretation or meaning for the image. But it is the knowledge of meanings that is essential to thought. Evidently, if images play a role in thought it is not through the "meanings" they convey because images, in and of themselves, have no essential meanings. Another way to state the objection is to say that it is what images are of, not the images themselves that are important in thinking (cf. Fodor, 1975). Again, Blanshard pointed out the same sort of objection. Thought is driven by what Blanshard calls "logical meanings," i.e., what we think of, not whatever images may be associated with the logical meanings. Blanshard used the example of a syllogism, which is clearly composed of a series of judgments based on the meanings of the terms. Suppose the conclusion called for the thought of a horse. Now, it is true that in a particular person an image of a horse might arise in consciousness at the time the conclusion was reached. But the process is clearly driven by the meanings involved. If an image used in making a judgment has a role, Blanshard suggested, "it will depend on the sort of help which that particular logical meaning needs to bring itself before the mind" (Blanshard, p. 280). Therefore, having images can certainly not be identical to thought. At most, images can have only a minor role in thought.*

3. WRONG PROPERTIES OBJECTION

This objection relies on the fact that "images," in the ordinary sense of the term, have size, shape, and other physical properties. Is there any sense, the descriptivists ask, to holding that there really are images in the mind? If we all agree that mental images do not have any physical properties, is there any sense at all in referring to them as "images"?

Daniel Dennett has provided a series of objections to mental images based on the wrong properties objection.

a. From the sub-personal account we can see that images, in the ordinary sense of the term, play no role in the neurophysiology of seeing or of imagining. In order for something to be an image of something else it must bear some physical similarity in terms of shape, color, or configuration to the object imaged. Obviously, there are no colored images of any size inside the head. There are images in this sense on the retina, but this is the last point in the neurophysiological process which transforms light impulses into vision at which there can be said to be an image. Neural firings that are responsible for seeing or imagining bear no similarity to the physical properties of images.

b. A related objection in the sub-personal account is Dennett's version of the homunculus argument. The homunculus objection is historically important and is sometimes considered to alone constitute sufficient proof that images do not exist, particularly in any way that connects them with perception. Dennett argues that in order for something to function as an image, it must be perceived. Images cannot, therefore, be the end product of perception. If what we saw were images of things and not the things themselves, there would have to be an internal agent, a man-analogue or homunculus, that could look at the images in order for perception to occur. But this man-analogue could not perceive any images unless it too had an internal homunculus that could perceive images. We have the beginning of an infinite regress. The point of the argument is that we can not introduce a new, intermediary entity into perception (the "image") and call it the object of perception without losing the essential idea of what it means to perceive: for the subject to see, directly, the object of perception.

c. Once images have been eliminated from the sub-personal account, that only leaves the personal account as a possible harbor for images. Dennett dispatches images from this arena by arguing for what he calls the "descriptional view of awareness." That seeing and imaging are actually descriptional in nature can be demonstrated by examples. If we imagine a man, we have no need to imagine any specific details about the man. A mental image may not specify, for example, a particular hair color. Similarly, if we imagine a tiger, we do not imagine a specific number of stripes. Nor is it possible to inspect the mental image of a tiger and count the stripes. Again, as in the sub- personal account, mental images are not like actual pictures that must, in virtue of their being pictures, show such details. In any description of a man or a tiger, we can specify as many details as we want, but the failure to do so does not change their basic character. A rudimentary description, such as "a man walking" is still a description. Seeing or imagining is simply the process of providing ourselves with descriptions. The illusion that there are mental images to be seen or inspected occurs because the process of creating these descriptions is often automatic. In fact, Dennett says, "seeing is rather like reading a novel at breakneck speed" (Dennett, 1969, p. 57). The mental images we have then, have none of the properties of actual pictures or images. The actual mode of our thinking at the personal level can be accounted for through descriptions.

Concluding Remarks

It is clear from a descriptivist point of view that images have little importance at best. They appear to be inert in thought, having no connection to logic and meanings that are the force and substance of the mind. Quite possibly, they are gross illusions, since all the work of the mind from perceiving to syllogizing is done by means of linguistic elements.

We can further characterize the descriptivist view by summarizing some of the more often repeated objections (for 1-3 see Kosslyn 1980, p. 29 and Pylyshyn in Block, 1980):

1. Images are epiphenomena. They are the result of thinking processes that have nothing to do with image experiences.

2. Images can be reduced to descriptions. Image experiences may "feel" visual, but that is just due to the way we have of talking about them.

3. Images don't exist. There is nothing that has the properties of real images in the mind.

4. Images can not carry meanings. Only words can carry meanings.

Pictorialists have offered responses to these objections. But Dennet's latter writing on images are also interesting in terms of forming a response. Dennett's views have changed over time from total rejection of images to a position that allows for their possible inclusion. In Dennett's own words, he has moved from "skepticism" to "agnosticism" (Dennett in Block, 1969, p. 59).

In a 1981 note appended to his original 1969 paper (discussed above), Dennett calls his pronouncement that no place could ever be found for images in the sub-personal account "rash and overstated" (Dennett, 1969, p. 59). In a 1979 article, Dennett says

Now, if anyone believes his mental images are information-carrying structures in his brain that deserve to be called images because they have certain structural and functional properties, and if science eventually confirms that the normal causes of that person's B-manifolds [results of having an image] are just such structures, then he can happily identify intentional object [the image] with cause. It will turn out for him that imaging is, and has been, like normal perception: just as pigs cause one to see pigs and cows cause one to see cows, images have caused him to believe he is having images. That is the scientific iconophile's prediction. (Dennett in Block, 1979, p. 102)

To a first approximation, this prediction has turned out to be true, according to the pictorialist side.

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