web version: June 3, 1999
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MENTAL IMAGES AS MENTAL OBJECTS
by
Anthony Birch, Ph.D.
I. Beginnings: Immediate Experience and a Definition of Mental Imagery
A. Experiments
1. Stare at the blue dot below for 30 seconds. Then close your eyes or stare at a white wall.
You should see an orange after image.
2. Recall, as vividly as possible a favorite vacation you have visited in the past -- perhaps a lake,
forest, or beach. "See" the scene and review the colors and shapes of the items that fill the scene.
3. Imagine that there is a bridge across the Atlantic from New York to London. Imagine that you
are driving onto the bridge by going up a ramp in New York. Now imagine that you are driving
across the bridge. What do you see?
4. Add 23 and 25 mentally. Did you have any mental images when you performed the addition?
Think of the concept of "freedom." Think of the concept of "slavery." Do you have any mental
images associated with these concepts?
B. Observations
Before beginning a philosophic analysis of mental images it is imperative to make some initial
observations about these experiences. What differentiates these experiences? What do they have
in common? There are many observations that might be made, and the reader should reflect on
them, but for the purpose of the view to be developed here, I wish to draw attention to the
following.
1. An after-image is induced. We are helpless witnesses to an after-image. Willpower plays no
part in the formation of such an image. The induced reaction appears to be entirely
physiological. After-images are definite sensations. There appears to be some "thing" of a
definite color and shape before us, but what is "seen" is unlike a physical object because it moves
when the eyes move instead of remaining stationary (as an ordinary physical object). It therefore
appears to float in space, or perhaps be momentarily "on" a particular surface.
2. This contrasts sharply with the vacation spot exercise. Memory images can be willed. They
are not, in any obvious way, the immediate result of a prior sensory overload or any other
physiological circumstance; they appear to be just the result of a simple mental act. Yet, memory
images are not distinguished solely by the presence or absence of an act of will. Unbidden
(unwilled) memory images, along with other sorts of images, certainly populate our conscious
mental lives. For the most part, there is little confusion about which are memory images and
which are not. Something else, therefore, differentiates memory images. It turns out that
identifying what this "something else" is is a rather elaborate philosophical problem, but most
people are likely to accept (at least initially) what seems evident from immediate experience:
memory images are qualitatively different from after-images. Unlike after-images, they are not
definitive sensations, they have no apparent location in space, and do not move when the eyes
move. If it is correct to say that after-images are literally "seen," then it would not be correct to
say the memory images are literally "seen" in the same way. Although we can invite people (or
cause ourselves) to "see" memory images, immediate experience indicates these are "seen" only
in a figurative sense.
3. Imagination images are yet another category of commonly-experienced images. In the exercise
above, there can be no memory of the item in question. Is this exercise of the imagination
qualitatively different from memory? Some may find that constructing an imaginative scene is
generally more difficult than invoking memory. But is this always true? Others may find that
the imagination image invoked by the example may be more vague than a memory image, but
again, this may not always be true. Another fact to note is that imagination images may simply
fail to materialize. Some people, for example, may find the example selected in the exercise so
preposterous or difficult to imagine that it blocks the formation of an image. We can, after all,
imagine that a bridge was built across the Atlantic without invoking any image. It seems, then,
that we have no specific set of qualitative differences to appeal to to distinguish imagination
images from memory images.
Still, imagination images seem to be different from memory images, even if we cannot always
specify the qualitative difference. Perhaps the difference can be found in answering another
question: how are imagination images generated? The intuitive answer, which was passed down
from Aristotle to Aquinas, then to Descartes, and finally the British empiricists, is that
imagination images must have their source in experience; otherwise, they be would be
inexplicable cases of something being generated from nothing. In some sense, imagination
images, as Hobbes insisted, must literally be nothing more than various bits and pieces of
memory images recombined and re-intensified to produce a new image.
Yet, this is a merely theoretical answer about the origin of imagination images, and there are
many philosophic difficulties with such an answer, as we shall see. Immediate experience -- or,
more precisely, a bare minimum of philosophic improvement on the testimony of immediate
experience -- simply tells us that our awareness of the difference between imagination images
and memory images is reflected in the fact that they are conceptually distinct. Memory refers to
actual prior experiences and imagination refers to possible or hypothetical forms of experience,
and this difference remains whether or not they have similar qualitative properties or share a
common origin. It is what types of experiences the imagery is referring to, or understood to
represent, not the sheer appearance properties of the imagery, that determines its type.
4. Finally, let us consider images associated with more elaborate mental operations or problem
solving: loosely termed, "thought images." Are there specific images associated with certain
operations or certain concepts? If so, what do these images have to do with these operations or
concepts? It turns out that these are two of the most contentious questions in the entire history of
philosophy, and one of the reasons for this contention is evident from immediate experience: our
thinking may or may not be associated with imagery, with no apparent pattern. Consequently, it
is difficult to discern precisely what the role of thought imagery might be. "Freedom" may not
invoke an image, while "slavery" may. The addition of simple sums (2 + 2) almost certainly
invokes no image, for example, while the problem in the exercise may.
It is easy to generate other examples that call into question what role images play in thought.
Consider whether there are images associated with the concepts of logical connectives such as
"and," "because," or "if/then"; or consider how we know the meanings of sentences that have a
high degree of abstraction, such as "the rate of inflation is directly proportional to the average
prime interest rate." On the other hand, consider the usefulness of imagery in the following
problems(1) requiring mental operations:
(a) Which is larger, a mouse or a hampster?
(b) How many windows are on the front of your house?
(c) What letter of the alphabet does the capital letter "n" look like when it is rotated 90 degrees counterclockwise?
(d) Imagine a cube. Now "paint" one side blue. Paint two sides that are adjacent to the
blue side, but opposite each other, red. Now cut the cube into nine smaller cubes (as in a
Rubik cube). How many of the smaller cubes have exactly one red side and one blue
side?
Other much more abstract operations also might be cited as examples of the usefulness of
imagery, for example, Einstein's famous thought experiment involving what it would be like to
ride a light wave.
Immediate experience, then, shows us very little about thought imagery. Generalizations about
them are difficult because there does not seem to be a consistent pattern to their occurrence.
However, we may note the following:
a) Thought images are conceptually distinct from imagination and memory images.
Thought images -- or the process of thinking while holding an image in mind -- may use
memory or imagination images, but the process of thinking is not exhausted in the image
itself. In thought imagery, the role of the image as tool or instrument of cognition is more
readily apparent.
b) Qualitatively, thought images may vary as much as memory or imagination images, if,
for example, they are loosely associated with certain concepts. They may be clear and
distinct, or vague and suggestive. On the other hand, the accuracy and completeness of
what I shall term "a visual presentation," i.e., an introspectible mental particular that has
the quality of being "visual," or, more precisely "quasi-visual" (to underscore that this
quality is to be understood by analogy to ordinary vision, not as identical to ordinary
vision), appears to be necessary for solving some problems (as in the "cube" example
above).
Some philosophers have sought to improve on these admittedly meager generalizations by
joining observations about the mechanics of the mind to additional metaphysical and
epistemological assumptions. For example, Hume argued that our thought should be completely
determined by the nature of the original, unembellished images available to us from perception.
Following Hobbes, and in the spirit of the mechanical notions of the universe introduced by
Newton, Hume thought that perception was nothing more than motions imparted to the sensory
organs. Memory and imagination were nothing more than a continuance of these motions in
decayed or less vivid and forceful form within the mind. The additional supplementation,
combination, or alteration of these original images is a pernicious propensity of the mind,
resulting in illegitimate concepts for which there is no epistemological support. On this basis,
Hume argued that we have no original perceptual image of causality, only the regular succession
of one kind of events followed by another kind of events. Therefore, we have no authentic
conception of causality. Again, we have no direct experience of an image of the soul or of God,
therefore there is nothing we can identify as conforming to these conceptions. Another example:
consider a mathematical point. The image of a point has no proper size at all. A small point can
be imagined as easily as a large point. Yet no matter what size the image of a point is understood
to be, the image cannot be divided and still remain as an image of a point. There is therefore,
Hume reasoned, no such thing as an infinitely divisible magnitude. The properties of the image
of the smallest imaginable magnitude do not allow this conception. Hume concluded that
mathematicians and philosophers were wrong when they appealed to our understanding of our
innate conceptions of mathematical realities in order to explicate a concept.
I shall leave aside the many issues that might be raised about Hume's argument. For my
purposes, Hume's view serves as an example of how imagistic thinking may lead us astray;
Hume's theory is a philosophical embellishment that is not justified by the mere presence of
imagery during thinking. Our concepts of such things as "point" are not and should not be
thought of as identical with an image. Indeed, an image will interfere with the proper concept,
for a point is merely a location, without any size or shape whatsoever. Hume's misguided
reasoning on this issue serves as a reminder that the role of images in thought is ambiguous --
and it requires far more than a simple identification of thought with images to elucidate their
role.
C. Conclusions: Definition and The Common Sense Object Theory
These preliminaries allow us to make tentative conclusions about the qualitative
experience and conceptual structure of having mental images. First, most people would probably
agree having a mental image is
"SEEING" SOMETHING THAT IS NOT THERE.
The quotes around the word "seeing" are necessary, for we do not mean we literally "see"
something that is not there when we are having a mental image. Even a person who is having a
hallucination does not actually SEE anything. What we mean is that having a mental image is an
experience that is somehow
SIMILAR TO ACTUALLY SEEING SOMETHING.
It involves what I have termed a visual presentation. Second, mental imagery experiences fall into a variety of conceptually (and, to a certain extent, phenomenologically) distinct types; among them: after-images, memory images, imagination images and thought images. The means of formation and the range of these experiences are not uniform, although they are linked by having a visual presentation. Having a mental image encompasses a wide variety of experiences, from those that are induced by easily identifiable physiological circumstances and have definitive sensation-like qualities (after-images) to those have no easily identifiable physiological causes, and whose quasi-perceptual characteristics may be difficult to describe or measure, but whose appearances are, at least to a certain extent, controlled by the will (memory, imagination, or thought images). There appears to be little to differentiate the qualitative aspects of imagery that occurs through some of the higher cognitive functions (memory, imagination, and thought), but we seem to be able to automatically (in most cases) differentiate the images (just as we do the functions themselves). For lack of a better term, we can refer to the capacity of automatic differentiation, as modal awareness of imagery types (or, more generally, as modal awareness of a cognitive function).
The fundamental notion that mental images involve an experience similar to seeing that occurs in the absence of anything that can actually be seen, has been used to formulate a formal definition of mental imagery in traditional (as opposed to contemporary cognitive) psychology. This definition has been articulated and defended by Alan Richardson, who defines mental imagery as follows:
Mental imagery refers to (1) all those quasi-sensory or quasi-perceptual experiences of which (2) we are self-consciously aware, and which (3) exist for us in the absence of those stimulus conditions that are known to produce their genuine sensory or perceptual counterparts, and which (4) may be expected to have different consequences from their sensory or perceptual counterparts. (Alan Richardson, 1969, pp. 2-3)
Writing again on the topic of the definition of mental imagery in 1983, Richardson defended this definition against the advances of cognitive science. The only concession that Richardson made was that the fourth criterion for mental imagery -- different consequences than an original stimulation -- should be slightly more hedged. Although we might generally expect different consequences in the case of mental imagery, it is not always the case. Directed imagination, for example, has been shown to produce effects that are identical to those experienced in the case of external stimulation. This minor point aside, Richardson has consistently maintained his view that this constitutes the definition of mental imagery that is appropriate to psychology.
Reflection on the testimony of immediate experience also, I submit, intimates, or provides the beginnings for, what may be called the common sense object theory of mental images. Having a mental image involves a form of awareness of a mentally presented quasi-visual particular -- an "object," if you will. This object status is borne out by a number of other facts derived from common experience. Many mental images seem to exhibit continuity over time. Memory images, for example, seem to be recalled over and over again, and imagination images, even though they may be transitory, one-of-a-kind images, seem to be stable while we are having them. Some mental images, for example, can be mentally "manipulated," in a manner analogous to physical manipulation, by rotating or moving them in an imagined space. Mental images, from a common sense point of view, might be regarded as "objects" in the sense that they are like "materials" or "constituents" in the overall economy of mental life. We seem to use or employ images as fundamental constituents in memory, imagining, and thinking activities, and we are subject or witness to them in the form of after-images or other forms of imagery such as dreams, hallucinations, and eidetic images.(2)
In what follows, I shall defend, broadly, what I call the common sense/traditional
psychology view about mental images. Within this broad conception, I shall also defend a
specific point of view about the metaphysics of mental images: namely, that they are a species of
mental object admitting of intentional characteristics through the modal awareness of imagery
types.
II. A Rejected Philosophic Approach
A. Fundamentals of Descriptivism
The view I defend flies in the face of a received contemporary doctrine. This doctrine is based on a family of views in contemporary philosophy of mind derived from linguistic/analytic philosophy since the turn of the century and articulated by such thinkers as Ryle, Dennett, and, to a certain extent, Wittgenstein. Currently, versions of this same doctrine, which I shall term "descriptivism," have also been adopted by cognitive psychologists.
Descriptivism relies on a set of more or less standard objections to mental imagery.
Among the claims common in descriptivist accounts:
1. Visual mental imagery experiences (i.e., as the traditionalist conceives of them, as mere pictorial presentations) are epiphenomena. They are the causally-ineffective results of other cognitive processes.
2. All (or nearly all) the causally-effective cognitive processes involve descriptions. Conscious imagery processes may "feel" visual and may seem to be involved in our cognitive processes, but that is just an illusion sustained by the imprecise way we have of talking about our experiences. Descriptive processes, some of them automatic, actually underlie imagery experiences.
3. Mental images, conceived of as the traditionalist's "pictures" in the mind, cannot exist.
There is nothing that has the properties of real pictures in the mind.
What I call strong descriptivism argues for all these claims. Taken together, these claims amount to the view that in a perspicuous explanatory language of causally-effective cognitive processes, references to mental images could be eliminated.
Strong descriptivism can be supported by four important arguments. It will be useful to
review these here.
Argument 1: No Images for Essential Concepts
Descriptivism capitalizes on a point already alluded to above: there are many important classes of ideas for which there are evidently no images at all. This applies, first of all, to the logical connectives and quantifiers (and, or, not, some, all). Clearly, these concepts are essential to thought. Since there are no images of them, images are inessential to the formulation of sentence meanings that rely on the meaning of connectives and quantifiers. By extension, if such individual logical sentence meanings cannot be accounted for, no series of meaningful logical steps can be accounted for in terms of meanings. The result is that images will be irrelevant in logically connected reasoning processes.
The intuition that images are necessary, or ought to be present in consciousness,
descriptivists argue, is just an ad hoc assumption made in order to bolster the idea that
something, derived with a minimum of alteration from raw sensory input, is responsible for our
ability to reason using universal terms. If we simply dispense with the assumption that the form
of our thinking must follow a picture-like derivative of sensation, we can view the matter another
way. We can look for clues to the substance of thought in linguistic practices and logic rather
than visual perception.
Argument 2: No Content
What is the meaning or content of an image? Is it obvious or "given," something we may know without learning or the necessity of language? The assumption that images have intrinsic or pre-linguistic meaning seems to lie behind the uses to which images have been put in imagist ontologies of the mental. How do we know, for example, that if we have a mental image of a chair, we know the image means "chair," rather than "example of furniture?"
The "twins argument," and its variations, has been used to drive this point home. Consider the mental image I would have of Tim or Tom, the identical twins. My images of the two are identical, but when I think of one rather than the other, I surely intend that my image, if it has any function at all for me, be understood as representing only one of them. If the images qua visual or imaginary presentations do not differ, what makes the difference in meaning possible? We must conclude that something other than visual properties of an image determines whatever meaning it has. At root, descriptivists point out, we are forced to admit every sort of image is fundamentally ambiguous, for in and of itself an image depicts or designates nothing specific at all.
Only some context can bring meaning to an image. Descriptivists argue that this context
is supplied by linguistic elements and the patterns of use that grow up around them. At a
minimum, an image needs to be verbally labeled, as it were, in order to signify anything at all.
Without such a designation, images are meaningless. As Wittgenstein remarked, not even God
could tell the meaning of a mental image.
Argument 3: The Language Trap
This objection holds that we do not in fact refer to any mental object when we speak of mental images. Instead, we refer to concrete, observable patterns of human speech and action. Descriptivists of this school claim that an analysis of language will show that we refer to mental images as a way of indicating that we can pretend, suppose, hypothesize or imagine that something is the case. All of these occur in ways that are publicly manifested in actions and habits of speech.
What we are really doing when we use terms that imply the literal existence of mental images is to employ certain modes of intersubjective communication that indicate our knowledge of human capacities. Although we seem to refer to mental images, this is in fact a replacement or metaphor for more complicated sentences that would explain our expectations and interpretations of the current state of affairs in other terms. For example, to say the artist has a mental image of David in the stone, is a replacement or metaphor for our belief that the artist is capable of carving the stone in the shape of David. These capabilities can ultimately be made directly observable. Such references do not actually refer to inwardly seen and completely private mental objects. To actually refer to private mental entities would be pointless in a world where the meanings of words are established by observable human practices.
The reason that we have lost sight of the metaphorical aspects of talk about mental
imagery is that we have been fooled by our habits of language. We become victims of the casual
use of language when we begin to believe that the words we use to communicate actually pick
out incorrigibly private items that exist in some mental space. Since linguistic forms of
communication ultimately rely on common agreement of objective reality, there can be no place
for any meanings that are attached to distinctively private mental objects. If we actually assumed
that all such mental states were intrinsically private, with no possible manifestation of public
behavior, language would be impossible. The fact that we have a public language about the
mental realm, then, does not prove its existence as a separate and inaccessible place filled with
special sorts of objects such as mental images. It actually proves the opposite, that all
suppositions of a private mental world and its content can ultimately be dispensed with.
Argument 4: Wrong Properties
This argument asserts that mental images lack the proper characteristics to be accepted into the class of true, proper, or actual images. Actual images are located in space and time, have specifiable parts, specific relations among those parts, and determinate sensible features such as size, color, and shape. This applies to all actual images, whether schematic line drawings or minutely detailed full-color photographs. Since mental images have none of these properties, they do not count as images at all.
Dennett has made extensive use of this form of objection, often combining it with related objections. It will be useful to review some of his arguments here, since together they result in a comprehensive, strong eliminativist view.
Dennett (1969) makes a distinction between the sub-personal or scientific account of images and the personal (conscious or phenomenological) account of images. In neither of these accounts, Dennett claims, do proper images intractably appear.
From the sub-personal perspective, Dennett argues, mental images are obviously not what he calls "proper," or actual, images at all. There are images on the retina of the eye, 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. The subsequent neural firings along the optic nerve, continuing to other portions of the brain which are responsible for seeing or imagining, have nothing in common with proper images.
A variation of this objection is Dennett's version of the homunculus argument. Dennett argues that in order for something to function as an image, it must be perceived. Images cannot, therefore, be the product of the process of perception; they can only be things that exist independently of us -- things we can literally see. If the perceptual process literally produced images, these would be images of things in the mind, and it would be those images that we would inwardly see and not the external things themselves. And, so the argument goes, since the internal images need to be literally seen in order to be recognized, there would have to be an internal agent, a man-analogue or homunculus, that could look at the images in order for recognition to occur. But this man-analogue could not perceive any images unless it too had an internal homunculus that could perceive internal images. We have the beginning of an infinite regress. The point of the argument is that we cannot introduce a new, intermediary entity into perception and call it (the intermediary) 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.
The defender of images will reply that if proper images cannot be said to exist in the mind from the sub-personal, or scientific, standpoint there is surely an intractable sense in which they must be granted to exist at the personal, or phenomenological, level. So much of our personal experience is structured by images, it seems ludicrous not to grant them existence. Dennett dispatches images from this arena by arguing for what he calls the "descriptional view of awareness." He argues that seeing and imaging actually involve descriptive rather than imagery-based processes. This, he claims, 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 specify particular features, such as hair color, but it need not. Mental images are not like actual pictures that must, in virtue of their being pictures, show such details. Mental images are more like descriptions in that we can specify as many details as we want, but the failure to do so does not change their basic character. Imagining, then, is actually the process of providing ourselves with descriptions, rather than images.
The illusion that there are mental images to be inwardly seen or inspected occurs because the process of creating these descriptions is often automatic. As quickly as we imagine something, we provide an inward description, automatically, that provides that actual content to our imagining. The so-called "image" does nothing at all, because it is actually a form of inner description. The same account of automatic descriptions extends to perception. Dennett says, "seeing is rather like reading a novel at breakneck speed" (Dennett, 1969, p. 57). There is an illusion of visual content, but the actual content of perception is conceptually ordered in the manner of language. Dennett concludes that mental images we experience have none of the properties of actual pictures or images. The actual modes of our thinking and perceiving at the personal level can be accounted for through descriptions.
As a final argument against the existence of images in the mind, Dennett gives his own view on the issue of whether mental images must consist of determinate parts in specific relations or can also be vague or indeterminate. Dennett argues that we know from direct experience that a mental image is vague and lacking in distinct, numerable parts. Dennett's example is the mental image of a tiger. How many stripes does it have? Dennett claims there is no answer to this question because a mental image of this type is inherently indefinite. No specific number of stripes is represented. Since this "mental image" fails to meet one of the criteria for being an image, it is not a proper image at all.
Dennett concludes that since mental images have none of the required properties, they are
not images in the proper sense at all. Mental images, by this criterion, cannot be said to exist.
B. An Evaluation of Descriptivism
Arguments 1 and 2 make valid points. As some imagists (e.g., Price, 1953) have themselves observed, there are indeed no images for the logical connectives necessary for deductive thought and the synthesis of concepts. It is also true that images, considered as mere visual presentations, have no intentional content.(3) Traditional imagists did, in fact, seem to assume that mental images could derive intentional content by means of visual similarity to perceptual objects that already have a self-evident meaning. Descriptivists are right to point out that there is no such thing as an image with a self-evident meaning, much less any string of images that could itself carry a meaningful thought.
Arguments 3 and 4 are far less convincing. Accounts based on these arguments place one at odds with the form of our conscious experiences. No one, I submit, experiences seeing as high-speed reading. If some analog to high-speed reading is what is actually occurring as an unconscious process, and this is invoked as an explanation of seeing, it places our whole relation to the external world on another footing, because language, not the operation of the senses, will ultimately structure our access to the world. In any event, the descriptivist account does not capture the nature of the conscious awareness of seeing, and, as a result, it does not address the nature of either visual memory or visual imagination. Seeing (and its visually-derived correlate "seeing," as applied to the notion of experiencing mental images) is almost completely ineffable; the experiential quality of it cannot be explained or described to a blind person. Seeing means being conscious of a unified, non-verbal, presentational whole with visually inspectable features. If, as seems self evident, visual memory and imagination are similar forms of conscious awareness that involve an ineffable visual component, some further development of the characteristics of the images involved is necessary.
Besides its objection to images, descriptivism is apparently also aimed at eliminating the notion that there is private, or exclusively mental, access to the elements of thought. Descriptivists argue we cannot make up, as it were, what the elements of thought will be. As Wittgenstein argued, one cannot inwardly say one word and inwardly mean another. I find that this argument also fails to do justice to the imagist perspective, or the traditional/common sense view. There is, undoubtedly, a confusion in the imagist perspective between the elements of thought and the means of thought. These sometimes appear to be equated. The descriptivist argument applies against construing images as the elements of thought, but it does not address the sense in which images serve as a means. As a means to thought, images can be suggestive, rather than definitive. We can hold in mind one image that serves as a symbol of a meaning that itself has no definitive symbol. The image of a lion can be used in thinking of the class of lions, but also for the class of animals, for which there is no image.
The descriptivist argument even fails to do justice to the indefinite nature of linguistic symbols. Sentences like "I am going to the bank" have an indefinite meaning (river bank vs. financial institution). The mere occurrence of the symbol element "bank" does not define the meaning of the sentence, whether it is uttered in public or is an "inner utterance." In fact, according to the common man's view, failure in communication between interlocutors would be due to there not being the same mental image in minds of the interlocutors when a given word was spoken. It would be the corresponding mental image of the intended kind of bank that would remove the ambiguity of such a sentence.
The descriptivist arguments provide some correctives to the imagist theory, but they
hardly provide the basis for a convincing alternative theory based on common sense. The privacy
of mental images is not a reason to suppose they do not exist, only that they cannot become the
entire basis for shared conventions of meaningful communication. The descriptivist arguments
assume that having descriptive information and having visual information amount to the same
thing. This is surely false. Any list of facts about Fred and Sam is no substitute for seeing Fred
and Sam. Descriptivists who equate seeing with high-speed description formation try to make
experience conform to a theory. Finally, while imagism falters in explaining thought,
descriptivism falters in explaining the presence of images in the lower powers of memory and
imagination. If all the information taken in during perception were really descriptional, there
would be no reason for it to "reappear" as an image in memory or imagination. Even if the need
for the reappearance of the image could be established, the generative process of image
construction would require still further explanation. The descriptivist would be forced to provide
an elaborate set of rules by which descriptions can be transformed into images (a supposition
presently faced by one branch of contemporary cognitive science, and which, in my view, has
only generated a theory that borders on the incredible). Either, then, the descriptional view of
perception is wrong, or descriptions become transformed into images in memory and imagination
for no apparent reason.
III. Mental Images as Mental Objects
1. Review of the Problem
One of the reasons that descriptivism has prevailed is that there are many difficulties with an alternative conception of the mind that appeals to mental objects rather than to linguistic processes and practices, behavior, or brain states. In this section, I defend, in spite of these difficulties, an object-oriented conception of the mind because I feel it is the only one that does justice to the presentational and conceptual facts about mental images.
Space prohibits a thorough exposition and defense of my view against the many forms of identity and computational theories that might rival it.(4) What I shall present here is primarily a positive account of the metaphysical basis for such a defense. There is, however, also one negative criticism of other accounts that is essential to this defense, and it is important to present this at the outset. I believe other accounts fail because they seek to substitute the fundamental metaphysical relations involved in the being of images with other relations. Consider a visible, public image. We can attend to the visible features of the visible particular which is the subject of our attention, or we can attend to what that particular represents. The distinction is crucial, and it applies to mental images as well. We do not literally see "images." What we see (for the most part) are real physical things, not the images of them. For an object that is merely seen is not an image per se at all. What makes something an image is that it is an image of something. A photograph or drawing of Clinton is an image of Clinton, not Clinton himself. Were this distinction utterly opaque to us, the entire (human) universe of primary objects, their signs, and the means by which these relations are established would disappear. Similarly, we can attend to the quasi-visual features of a mental image, but this is not (alone) what gives it its signification or power in mental operations. It is, rather, what the image represents -- a prior experience, a possible experience, a tool in problem solving, a set of abstract relations, a color, a shape, a size, location, and so on -- that provides its potency for mental operations. I shall therefore adopt the position that images, of every type -- both public and mental images -- are best described as relative beings, and relative beings that are such in virtue of the fact that they are representations. The reason for this is straightforward. Public images are real, but are relative beings because they owe their existence qua images to the existence of other things. This is true of anything (e.g., also symbols) that are representations of other things. Existing as a representation can be signified formulaically.(5) When we say
X represents Y to Z,
and X is an image, Y the object it represents, and Z a conscious agent, we express the fact that representation is a triadic relation, and X is in relation to both Y and Z. If one of the terms is removed from the relation we are no longer speaking of the same thing.
This is not an insignificant metaphysical point, for some philosophers apparently believe that representation is only dyadic. They assert
X represents Y
can be an unadorned fact about the world -- a fact not requiring the existence of conscious agents (Z). Dretske's philosophy of the flow of information in the natural world hinges on this interpretation of what it means for one thing to represent another. Other views about what it means to be a representation are sometimes implied or stated in philosophic accounts. Among them:
X causes Y,
X is correlated with Y, or
X functions as if it were Y.
It is often argued that one of these relations is sufficient to characterize how physical states in the brain are "representations." This is a point that deserves a book (at least) to completely treat it. Here, I shall simply assert that the only correct way, and, not coincidentally, the way most compatible with common sense, to understand representation and the being of images is to insist that they are inextricably bound up with human intentionality and the formulaic expression that X represents Y to Z.(6)
Let us now turn to the notion of object status of mental "objects" specifically. I put quotes around the word "object" because even elementary considerations show that mental images do not fit our concept of ordinary physical objects in the external world. Mental images do not literally have size, shape, or color. There is, as Dennett has argued, undoubtedly a tendency to use object language in a way that results in speaking of mental images as if they could be literally seen by an inner eye. The results in the homunculus problem. Descriptivists attempted to remove the homunculus by showing how linguistic elements and concepts could fulfill the role attributed to images. The descriptivist correctives, I argued, went too far, resulting in loss of a correct description of the phenomenon to be examined.
I have attempted to consolidate common sense with science and philosophic psychology by accepting a definition of mental imagery as referring to quasi-sensory or quasi-perceptual experiences. This definition also accepts the fact that these experiences may be significantly like perceptual encounters with actual objects and that these mental encounters may have consequences similar to their sensory or perceptual counterparts. The sense of "objects" implied by this definition stands in need of elaboration.
In short, the philosophic task remains of attempting to sort out what the scare quotes around the term "object" actually amount to. We need to clarify how such objects can be said to be "in" the mind, in what manner, if any, they may be said to exist, and how, or whether, they obtain the properties they seem to have.
I shall begin by briefly describing two competing views about the nature of mental
objects. The two views are the adverbial account developed by Ducasse and Chisolm and the
act/object account defended by Moore and Jackson.
2. Ducasse's Adverbial Theory
Ducasse states his theory as one to be contrasted with G. E. Moore's "object" or sense data theory of conscious awareness. Moore pointed out that in the case of sensing something blue, it is possible to distinguish the consciousness of sensing from the sensation itself. The sensation is of blue, rather than of, say, green, so there is a distinct, identifiable sensum or object that we are aware of that differs from other objects. At the same time, there is an element that remains the same in both sensations -- consciousness -- so it is the objects, not consciousness, that differentiates the cases. Normally, we think of "blue" and our awareness of it as being unified or at least concurrently existing, but, as Moore pointed out, there is no logical objection to the possibility that "blue" and our consciousness of it could exist independently. This establishes the logical possibility of an unsensed sensation or sensa that has independent existence. Moore introduced this possibility in order to argue against idealism. By arguing against the idea that consciousness of sensory qualities necessarily implied the existence of something "in the mind," rather than something "objective" and possibly capable of independent existence, Moore hoped to weaken one of the central arguments in support of idealism. This argument is that the being of sensible objects consists entirely in their being perceived; as Berkeley put it, esse est percepi. Moore's argument is that the proposition that the esse of anything consists in its being perceived does not even hold true in those cases where consciousness and its objects seem most firmly united, i.e., in the case of the apprehension of sensory qualities such as blue.
Ducasse argued against Moore not in order to defend idealism, but in order to show that esse est percepi is true for a certain class of conscious processes. In Ducasse's view, this does not result in idealism, because he distinguishes between the content of conscious processes and the object of conscious processes. In the case of consciousness of blue, blue is the content of consciousness, not the object of consciousness. For this content, it is true that esse est percepi, for the content exists, although it has no independent existence apart from the
process of which it is a part, and this is the only mode of existence it can have. The object of consciousness, on the other hand, must be an object external to consciousness, having an independent existence.
How are we to understand the mode of existence of the content of consciousness? Ducasse claims that this is a mode of existence of "things" that we readily accept as part of the real world. Consider a waltz. Waltzes are things that can exist, but a waltz has no existence apart from the act of people dancing it. What we find in case we are looking for instances of waltzes, and what we come to know, if we seek to know walzes, are not some independently existing things, but some recognizable parts of a particular kind of process. Similarly, in our consciousness of blue, we become aware not of something independently existing but something that is part of the conscious process itself: "what is known by the knowing process is then its own determinate nature on a given occasion" (Ducasse, 1951, p.260). To say we have consciousness of blue, then, is ultimately a way of characterizing a particular mode of a conscious process. As a waltz is a mode of dancing, consciousness of blue is a particular mode of "being aware of." It is not the case, then, that there is any object that literally is blue when we see blue. "Blue" is not something independently existing in the world but only something brought about by, and inseparable from, conscious activity. This activity takes on the mode of awareness of its own specific form of activity we call sensing blue.
In light of these considerations, Ducasse claims that the essence of the activity of seeing
blue would be most perspicuously formulated by eliminating the noun "blue" altogether. The
process should be described as "seeing bluely" -- a process verb, adverbially modified to indicate
its particular kind. Hence, "blue" is not something objective at all; it is a species of conscious
awareness, not an object of awareness.
3. Chisolm's Support for the Adverbial Theory
In support of the adverbial theory Chisolm (1966) argued that the object theory utilizes various forms of invalid inferences and unnecessarily multiplies the entities necessary to explain perception. One error is to conclude from the premise
(1) something appears F
that
(2) something presents an appearance that is F.
This error is easily seen by substitution. From, "this ship appears water-tight," we cannot conclude that "this ship presents an appearance that is water-tight" (Chisolm in Rosenthal, p. 382). This, Chisolm would say, is the kind of error Moore commits when he attributes "blue" to a sense datum or an appearance in consciousness. From the fact that there is an appearance of blue, we cannot conclude that the appearance itself is blue. Reasoning in that vein will end in infinitely multiplying entities. For if any perceived object A with property X generates another entity (an appearance) B, having property X in virtue of which A is said to have X, then B must also generate an appearance entity C, in virtue of which it may be said to have property X, and so on. In order to eliminate these unnecessary entities, Chisolm concludes, following Ducasse, that it is necessary to avoid attributing properties to appearances.
Chisolm's argument is an important one to bear in mind in determining the issue of the
qualities of mental objects. For the purposes of the discussion below, I shall accept Chisolm's
argument that to attribute properties to appearances themselves is an error. I shall refer to this as
"the sense datum error." This error is closely related to another one that we must also consider.
To say that from "I see a ghost" it follows that there exists a ghost that I see, is also an error. All
of the mental images we report might be likened to such an example. I shall refer to this as "the
existence error." We should note that each of these errors might be corrected by a suitable
interpretation placed on terms such as "appearance," "see," or "exists," but that without such
embellishments they remain logical errors.
4. Moore's Objection and the After-Image
It is important to note that what we have said so far about the adverbial theory is only indirectly related to our investigation. Ducasse and Chisolm concentrated on an analysis of perception as an adverbially defined mode of consciousness. In one fundamental sense, it may even be said that Moore and Ducasse are bound to agree on the essence of perception as it applies to our investigation. Both accounts endorse versions of common sense realism: independently existing physical objects are the objects that we know. Whether the means by which we know them are designated "contents" or "objects" of consciousness is immaterial as long as it is recognized that some form of conscious mediation is involved in the process. When a physical object is present, the nature of this conscious mediation may be debated; whether it is most accurately designated a mode of consciousness or whether it involves consciousness and a sense datum is a problem, but it is not precisely the same problem as the one we face in the case of mental images. Ex hypothesi, for the purposes of this investigation, there are no conscious mental images involved in perception.(7) We are concerned with the relation of consciousness to its "objects" when consciousness is not directed toward an external stimulus.
Now, both Moore and Ducasse did address the problem of one sort of mental image we have mentioned: after-images. Moore thought the ability to see blue in the absence of any physical object supported his position, since the after-image is a form of direct presence of a perceptible quality in consciousness. Since the question of the ultimate relation between consciousness and the physical object was now ancillary, the after-image case supported even better, he thought, the claim that consciousness is necessarily of non-physical objects (Moore in Ducasse, pp. 282-283). Ducasse responded that after-images are not simple objects (of any kind) at all. Rather, they are complexes of qualities. That is, an after-image is not a single intuition of a single color quality but always appears with the additional qualities of size, shape, and location. While Ducasse allowed that there was a sense in which the after-image constituted a whole, and might even be designated a "sensa" or "sense datum," he held that (1) it was nevertheless composed of distinguishable elements, and that (2) in order to determine the status of the whole, one need only determine the status of the parts because "the existential status of the sense datum...can be no other than that of its elements" (p. 284). The elements, in turn, were most aptly described in terms of modes of consciousness since they literally were qualities and did not themselves bear qualities (as Moore's sensa were reputed to bear). In order to formulate the experience of having an after-image according to the adverbial format, Ducasse suggested that we should most properly speak of seeing an after-image, not just bluely, but, for example, bluely, squarely, and largely.
We now have two accounts, both of which seem to be partly right. Ducasse's account
seems to be right from the standpoint that in the absence of a physical stimulus, certain forms of
conscious awareness should be thought of as modes of consciousness itself. Moore's account
seems to be accurate in pointing to the phenomenological fact that we encounter after-images as
if they were separate objects and not parts of consciousness. At this point we will do well to
consider another aspect of the object theory.
5. Jackson's Object Theory
Jackson (1976) argues that the adverbial theory is not successful in eliminating mental objects because its proposed linguistic recastings of the nature of our experiences fail to do justice to the nature of these experiences, specifically sensations and after-images. While Ducasse has argued that his own theory correctly represented the common sense view and attributed the failure of our linguistic conventions to conform to this to "linguistic inertia" (p. 278), Jackson thinks our linguistic conventions correctly indicate the true state of affairs. By convention, we do in fact refer to many sensations and mental images as singular terms identifying something existing at a particular time and (sometimes) in a particular place.
Jackson claims that mental objects can be eliminated only if we can find a correct, non-question begging analysis of a statement such as
(1) Bob has a pain.
A non-objective account needs to show that "pain" (or some other named sensation) does not appear in a way that logically implies its objective status. But it is immediately obvious that there is not, for example, such a thing as someone simply having "a pain." Bob's having a pain implies that he has a pain somewhere, and this gives an objective status to the pain. The adverbial approach, in order to capture this, must resort to awkward constructions such "Bob senses painly-legily." Similarly, the adverbial approach cannot successfully recast the meaning of what it is to be conscious of an after-image that has more than one property. For example, if (following Ducasse) the suggested formulation for sensing a blue, square after-image is
(2) I sense bluely and squarely,
then this cannot logically differentiate two different cases:
(3) I sense one blue thing and one square thing,
and
(4) I sense one thing that is both blue and square.
According to Jackson's critique, then, Ducasse's proposed solution to identify the locations in the visual field as modes of consciousness simply cannot work. Ducasse's formulation "I sense bluely, squarely" cannot distinguish between sensing an indefinite patch of blue and a square from sensing a blue square. Nor will separating the visual locations of such color and shape intuitions do the trick. Sensing "leftly bluely" and "rightly squarely" would indeed remove ambiguity, but it also implicitly introduces a new form of object identification into the description of the phenomenon. The locations in the visual field are themselves species of objects. We have a sensation "here" or "there" in the visual field, thereby logically implying an object-like status to the segments of visual space themselves. These spatial object areas, designated "left" and "right," then remain as static (non-adverbial) givens even if the mental objects "in" them can be designated as "modes" rather than objects.
We see, then, that there are substantial reasons for accepting that a linguistic account also
terminates in the need to accept the object status of mental images.
6. The Need for a Metaphysical Account
Let us review and assess these accounts. Ducasse's account seems physically correct, even if metaphysically ambiguous. Moore's account seems phenomenologically correct. Jackson's arguments are reminders of the fact that mental images are linguistically identified as objects, even if only minimally as objectively-given aspects of the visual field.
If both Moore's phenomenological and Jackson's linguistic accounts of mental images
grant them an object status, is there a metaphysical account that conforms to this?(8) In what
sense, if any, can we grant object status to mental images? Chisolm's arguments are reminders of
the fact that in any object account we need to address the sense datum and existence errors.
What we need in order to defend an object account, then, is to remove the remaining
metaphysical ambiguities while addressing Chisolm's strictures.
7. Desiderata for an Object Theory
I aim to retain, as far as possible, (1) the characteristics of mental images that have been found central to the common sense approach advocated here and (2) the most valuable insights into the nature of mental images introduced by discussion of the act/object and adverbial accounts. I propose that a metaphysical account of mental images should address and, if possible, decide upon the issues related to the following characteristics.
(1) Object Awareness. Mental images are experienced by us as encounters with presented properties. These properties often cohere, if only temporarily, in a way similar to the coherence of properties given with external objects.
(2) Mode Awareness. We are aware of most mental images (mental images used or created in normal waking states) in a mode that identifies them as experiences distinct from ordinary perception. We are aware of them as being like a sensation or perception of an ordinary object. Imagery experiences, in other words, occur with an accompanying awareness of the context, one that identifies our experiences as being of a certain type or in a certain mode of conscious awareness.
(3) Self-Conscious Awareness. When we are conscious of a mental image (in normal waking states) we are not only conscious of the image, we are self aware, or aware that we are aware of the image.
(4) Relative Being. Mental images are, or can be, understood to be representations of visually similar visible objects. Like publicly visible objects, their being qua image is derivative of the existence of conscious agents who understand the appearance properties of mental images as relative rather than absolute.
(5) Causal Relevance. The common sense view is that mental images bear information in memory and act as tools of imagination and thought. In this sense, they act as mediating elements in a series of causally connected events (e.g., the derivation of a theorem, or the shaping of a statue). In other cases, mental images play a more immediate role and may be identified as either causes or effects themselves. Dreams or after-images, for example, may be either the results or causes of other mental or physical events. Barring strong evidence to the contrary, mental images should be accepted as fitting into the normal causal chain of events in our everyday life.
(6) Inexistence. There should be some identifiable sense in which mental images can be said to "in" the subjects that experience them. This would help give some intelligible meaning to the commonly-accepted idea that statements like "she has a mental image" can be a true statement correctly reflecting the implied linguistic analysis that refers to an inner object.
More needs to be said on the way in which we are aware of the various types of imagery
(the mode awareness in which mental images occur) and the various properties we may say
"inhere" in the mental images belonging to these types. In this paper, I shall be primarily
concerned with the last four desiderata.
8. Self Awareness and Object Awareness
When we are conscious of a mental image we need not be conscious of it alone. We can also be aware that we are aware of the mental image, and this, as Moore says, is one of the aspects we mean to capture when we say that something is a mental, as opposed to a physical, fact. Moore says we are aware of the object of awareness and aware of that awareness in exactly the same way (Moore, 1903, p.449). This analysis cannot be entirely right if it is meant as a full explanation of how awareness is related to objects in consciousness. Aristotle's treatment of this issue indicates one of the problems. Aristotle asked by what sense could we be aware that we are aware of a colored object (On the Soul, 425b10-427a15). Aristotle felt there were only two options. First, we could say that there are two senses aware of the same object. The first sense would be aware of the object alone and the second sense would be aware of the object plus the awareness of that object. This appears to be Moore's solution. The problem with this solution is that the second sense does not yet specifically achieve self awareness. It only posits a higher-order awareness that bears a relation to another awareness. This higher-order awareness in turn needs to be aware of itself, but if this is accounted for by a still higher-order awareness, we have the beginning of an infinite regress.
Aristotle thought the only solution was to accept it as a brute fact that there is a single
sense that is aware of itself and aware of its object in the first place.
Figure 1. Two Models of Consciousness and its Objects. Moore's model (left) and Aristotle's
model (right).
Whether or not Aristotle's pre-Cartesian conception of self-conscious awareness can be likened to our contemporary view is controversial (see Modrak, 1987), but this need not concern us here. Our concern is the general form of the relation between subject and object.
Including self-awareness impacts how we understand the way in which the object is "given" in consciousness. It means, among other things, that we are not aware of mental objects simpliciter, e.g., as a fly might be aware of a moving object. As many imagists have tried to point out, our self-awareness carries with it some nascent knowledge of the individual's own cognitive resources that may be applied to an image. One is aware that other images are "present in power" (as Hume observed), that a rotated image might have a different interpretation, that an image might be of something impossible in the actual world, and so on.
When we refer to the fact that self-awareness is involved in imagery consciousness, this also introduces a possible way to understand how the object can be in the subject. We may be tempted to say, as in Ducasse's theory, that what we are aware of in consciousness is not an independent object but a mode of consciousness itself. It is not, after all, the subject that is "colored," or "square," so it must be some part or sub-process within the subject that has these properties. But if we attribute to some part or sub-process these properties we shall commit the sense datum error. It would be more appropriate to say, then, not that the parts or sub-processes have properties but that they are properties. Still, this does not seem correct, because the question reasserts itself: properties of what? Not the subject -- that has been excluded -- and to say "of an object" just starts the problem again.
The above considerations lead us to question the nature of the independence of the
subject and the object once more. The fundamental intuition that consciousness of mental
images is due to internal processes in the subject is a strong one, and it may be that one could still
conceive of the inner object as a part or sub-process of consciousness. Aristotle took up a similar
consideration when he asked how the subject and the object could be separate and yet "one."
Aristotle reasoned that the object and the sensing of it are "one" in the sense that they come to be
simultaneously. That is, the object, qua something perceived, is only potentially perceptible until
it becomes actually the percept of a sentient being. Likewise, a sentient being (or a power of
sense) is only potentially conscious of something until it senses something. The two
potentialities become a single actuality in the moment of perception. Yet, Aristotle claimed, "the
distinction between their being remains" (On the Soul, 425b25) and, he added, "they differ in
their modes of being" (On the Soul, 426a15-20). We shall follow Aristotle's suggestion, and turn
next to examining the mode of being of the inner object in the hope that this will clarify its status
as an object.
9. The Mode of Being of the Inner Object
According to our desiderata, we want to capture the sense in which images are relative beings. At the same time, we want to keep, if possible, some intelligible notion of the inexistence of the object. The first question, then, is to consider how a relative being could be in a subject.
Recall that just as in the case of perception of a visible image, we can, when attending to a mental image, attend either to its visual features or to what it represents. To appropriate the terms "content" and "object," we can make the visual content the object of our attention. And, just as in perception, we have no consciousness proper of a mediating visual content qua representation unless we are aware either (1) that it at least potentially bears a relation to something else or (2) what, specifically, it does in fact refer to. This conforms to the analysis of visible images we gave at the beginning of this chapter, where "X represents Y to Z" was given as a formula indicating what is meant by apprehending an image.
What sort of circumstance can sustain these relations? It seems clear that this is quintessentially a circumstance brought about by the existence of conscious interpreters and that the apprehension of "objects" not physically present is a mental phenomenon without any obvious counterpart in the physical world. If, therefore, fundamental aspects of the mental realm are structured this way, we ought to admit the existence of objects that are part of this structure. Also, there seems to be a logical constraint on our description of the relations. If we assert the reality of the relations among X, Y, and Z, we ought to assert the reality of the relata -- including, therefore, mental objects.
However, such considerations about the relative being of mental images reach a stumbling block when we attempt to address simultaneously other desiderata, such as inexistence. There does not seem to be any clear way to explain this notion. Suppose we say, despite also wishing to claim that the subject and the object of consciousness are metaphysically distinct, that the object must (since it is "in" the subject) be a part or process within consciousness. Aristotle provides an interesting account of this possibility. He asks, "can a part of a substance, whether a contiguous part or a process within it, have relative being? To this question Aristotle answered "no" (Categories, 8b15-25). A part of a substance does not conform to the requirement that when we cognize a relative thing we also cognize that to which it is related. A part of anything is not necessarily experienced as a part. For example, an old car part lying in a field is not necessarily apprehended as a part of any whole. Aristotle concluded that objects of knowledge and perception bore what was a singular type of fundamental relation to the substances in which they inhered: they were "in" the substance, but not as a part. Perhaps, then, this is the best that we can do to explain the notion of inexistence.
Let us now describe how these considerations come together in the form of a paradox. We have said that mental objects can be understood to be "in" the subject but not as a part. Yet, this is a strange, and perhaps unintelligible, way of putting it.(9) Mental images themselves cannot literally be of a certain size, shape, or color. That is the sense datum fallacy. Yet we are conscious of presented shape and color properties that seem to inhere in an object, and the relations among subject, inner object, and what is represented seem to be real. We should not state, however, that simply because this is the form of our experience that the object itself unequivocally exists. That would be the existence error. Shall we then say that there exist no objects that have these properties and that there exist no objects that are literally "in" us, but that we are nevertheless aware of them as objects in consciousness? That would indeed be paradoxical.
To state the problem another way, we have in mental images consciousness of properties that we think of as belonging to an inner object, but we cannot assert that an inner object exists in any physical fashion. When it comes to defining how this is to be understood, it appears that we can state this only in a way that appeals to an intuitive understanding of the very notion we are trying to clarify. To say that the "object" is "in" the subject, but not as a physical part, is just to aver to the way in which mental objects are intuitively understood to be "in" consciousness.
One form of solution to this paradox can be derived from Santayana's philosophy of critical realism. Santayana distinguished between those things which have being or reality and those we should most properly say actually exist. The things that exist are beings in flux, determined by external relations and "jostled" by irrelevant events (Santayana, 1946, p. 42). The term "existence" was to be reserved for "facts and events believed to occur in nature" (Santayana, p. 47). There are, according to Santayana, also entities that have being but not existence. These are what he calls "essences," and they include the immediately given sensa of consciousness presented to us in perception and imagination. They include, in other words, what we have described as the appearance properties or pure visual content of mental images. These immediately given data of consciousness are not in nature; rather, they are the evidence by which I come to believe in the existence of exterior things that are in nature.
This account has the advantage that it coheres with a number of the desiderata we have listed. Mental images are real things that we encounter and we can also say that individuals have them. For what the facts and events of nature include, according to Santayana, are such facts as someone intuiting an image. What exists in the physical world is the person having the mental image, but not the mental image itself (Santayana, 1923, p.45). This allows us to say that it is true that someone has a mental image and that the mental image has objective being, but does not commit us to say that it has physical being.
This way of describing the facts also has the advantage that it defuses the question of how mental objects are "in" subjects. Objective essences are neither in nor out of the subject, and they are not parts of anything at all. They have their own objective being outside of time and space. The base fact of our world is that consciousness is able to know essences without altering the essences themselves.
On the other hand, this view is difficult to maintain in light of the desideratum of causal relevance. In Santayana's Platonic realm of essences, essences themselves are causally inert. How can they be effects or causes of human acts if they belong to an entirely different metaphysical realm?
I leave this final riddle unsolved. To solve it would be to give a more complete analysis
of "nature," "physical," "cause," and other terms. In short, it would be to review the entire scope
of the mind/body problem. Officially, I shall leave the metaphysical status of mental objects an
unsolved problem. On the other hand, I believe that there are no metaphysical bars to exclude
such objects.
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September, pp. 68-76.
1. All of these examples are drawn from contemporary investigations in cognitive science. The point of using these examples is that however obvious it is that imagery is involved in these tasks from the common sense point of view, not one of the examples remains uncontroversial within cognitive science: whether or not images are involved at the root level of cognition, as defined by cognitive science, is one of the most hotly debated issues in all of the contemporary literature.
2. The latter three were omitted in the inventory of images from immediate experience above for the sake of brevity in this text. They must obviously be considered in a full treatment of the topic, and I have done so elsewhere.
3. This is not to admit that descriptivists are correct in implying, as they often do, that mental images have no content. Mental images, qua quasi-visual mental particulars, do present qualitative content.
4. Such a defense and exposition is present in my dissertation.
5. I am indebted to Professor Charles Landesman for this formulation.
6. The point of view articulated here, although it may depart in its subsequent metaphysical implications, is also intended to be consistent with the view developed by Searle and others, who have argued that the concept of "understanding" does not admit of reduction to terms involving only the manipulation of finite physical particulars related only by the laws of mechanics.
7. A point that might be debated, but one implied by the common sense conceptual distinction between ordinary seeing and having quasi-visual experiences through mental imagery.
8. I owe this way of stating the "object problem" for mental images to Charles Landesman.
9. Aristotle equates, at one point, being in a subject but not as a part with "being incapable
of existence apart from the said subject" (Categories, 1a22). This is a less unintelligible way of
putting it, but it also locks in a certain metaphysical interpretation of the mode of existence of
mental objects. This is point that might be pursued further.