Perception and Other Minds Fred I. Dretske Noûs, Vol. 7, No. 1. (Mar., 1973), pp. 34-44. Stable URL: http://links.jstor.org/sici?sici=0029-4624%28197303%297%3A1%3C34%3APAOM%3E2.0.CO%3B2-T Noûs is currently published by Blackwell Publishing.
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Perception and Other Minds UNIVERSITY OF WISCONSIN
Assuming for the moment that I know it, how do I know that there are any other people in the world besides myself, conscious human beings who think and feel in ways similar to the way I think and feel ? One of the answers that I can think to give to this question-an answer that strikes me as both true and appropriately responsive-is that I can see that there are other people, a great many of them, If asked how I know that there are any other Volkswagens in the world (besides my own) I would reply, similarly, that I see them wherever I go. Volkswagens, after all, are easy to spot. But so are people. We may someday have a more difficult time (Is this a person or a cleverly contrived robot? Is this a person or a highly evolved orangoutang ?), but as things now stand a person is, in normal circumstances, quite an easy thing to pick out-easier, certainly, than apple pie. This being so, what or where is the problem of other minds ? Being minded is, I take it, part of what we mean to attribute to something when we speak of it as a person. If there is no problem about identifying people, there should be no special problem about deciding whether there are other minds or how we come to know this. We routinely speak about seeing that there are some people in the waiting room, passengers on the bus, students in the office, and a crowd of people listening to the speaker. If what we routinely say is true, if we do see this sort of thing, then this is how we know (or, at least, one of the ways we know) that there are other minds. Furthermore, there are a great many other things of a more specific nature that we commonly say we see that imply that we know that there are other conscious beings in the world besides ourselves. I do not always know when my wife is angry, and some of the times that I do know this it is not because I can see that she is; but there are occasions, or so I believe, when I can see that she is angry. Knowing her as I do I can also see when she is tired, bored, irritated, uncomfortable, frustrated, and interested. Since
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I believe I can see this sort of thing, I do not believe that there is any particular, any special, problem about other minds. No particular, no special, problem of other minds because the way I have of knowing that there are other minds is the same way I have of knowing that there are (other) bodies (e.g. Volkswagens). T h e way I have of knowing that my wife is angry is the same way I have of knowing that her jaw is set and her eyes have that characteristic glint. If there is a problem about other minds, then there is a problem, the very sameproblem, about other bodies. I do not mean to suggest that we can ignore epistemological scepticism, that we can simply assume that what we ordinarily say about what we see, and about what we know, is true. Quite the contrary. There are, I believe, genuine problems in the analysis of knowledge, real difficulties in coming to understand just what knowledge is and how it can be obtained in perceptual situations. Common sense may be right, and I believe that it is, but the epistemological case against scepticism cannot rest with the observation that it is contrary to common sense (or contrary to what we ordinarily say). What I mean to be suggesting when I say that there is no particular, no special, problem about other minds is not just that we commonly say we see that another person is angry or upset (thereby implying that we know that he is angry or upset in the same direct way we know that he is fat or bald). This much is certainly true, and perhaps worth remarking, but it doesn't get us very far. For comparable remarks could be made about our attitude toward physical objects; we go about our everyday affairs quite oblivious of sceptical difficulties and speak as though we could see that there were flowers in the vase and cookies in the jar. But the sceptic remains unimpressed. T h e point I mean to be emphasizing in my attempt to demote the problem of other minds is that, as commonly conceived, our way of knowing (or one of our ways of knowing) about other minds (e.g., that his finger hurts) is exactly the same as our way (or one of our ways) of knowing about other bodies (e.g., that his finger is in his mouth). We speak (more frequently than one might suppose) of being able to see that he is losing interest (getting tired, etc.), and we do this in as casual a way as we speak of seeing that he is losing his hair (getting fat, etc.). If there is a problem of knowledge, if there is a problem about how we can see what we commonly purport to see, then it would seem that these difficulties affect both our knowledge of objects and our knowledge of other minds. For, as commonly conceived, there are no greater epistemological barriers in the one
case than there are in the other. Our way of knowing is, in both cases, the same. This, at least, is the thesis I wish to argue in this paper: there is no special problem of other minds-no problem, at least, that isn't already present in our (putative) knowledge that there are other bodies that behave as though they were minded.l Some philosophers seem to think that there is a special difficulty about other minds because, to put it roughly, we can't see other minds. They are unobservable. You can see the smile (at least the upturned mouth), but not the thought 'behind' it. You can see the perspiration, the flushed face, the wrinkled forehead, the squint, the jerky motion of the arms, the hunched shoulders, the clenched fist, and the trembling lips, but you can't see the fear, the embarrassment, the frustration, the desire, the pain, or the anger that the other person (presumably) feels. Since this is so, we have a difference, a rather important difference between our knowledge of other minds and our knowledge of other bodies. T h e conclusion we are apparently supposed to draw from this set of remarks is that there is a greater difficulty in seeing that he is sad than there is in seeing that his mouth is turned down because, though we can see his turned down mouth, we can't see his sadness. Before examining this argument, let me spend a few moments with the premises themselves. Is it true that we cannot see a person's excitement, fear, anger, or pain? Is it true that we cannot see those states, conditions, events, processes, episodes (or what have you) that constitute the mental life of another person ? I t seems not. I say 'it seems' because I suspect that the answer one gives to this question will depend on how devoted one is to the utterances of the man on the street. That is, we may be reminded that people do say they can see the anger in another person's eyes, see his mounting fear or frustration, and see the man's embarrassment. Such statements suggest that another person's anger, fear, frustration, and embarrassment are visible (can be seen). Nonetheless, despite the occurrence of such expressions, the examples are not very compelling. For it is, I think, reasonable to construe these claims in such a way that they do not imply that another person's fear or anger is something that can be seen. I n saying that one could see the fear in his eyes, for example, it seems plausible to understand this as a statement to the effect that one could see that he was afraid by looking in his eyes, that one could see (by his eyes, or in his eyes) that he was
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afraid. Seeing that a person is afraid, however, is something that we can do without supposing that the fear itself is visible (we don't have to see a person's wealth to see that he is wealthy). Similarly, when we say that a person 'blew up', could no longer conceal his anger, we do not mean that everyone could suddenly see his anger (though, I admit, we might easily say just that). What we mean is that everyone could now see that he was angry, that he was angry became evident. What is evident (can be seen), however, is a fact (that he is angry), not a thing (his anger). This discussion of whether we can see another person's fear or embarrassment is, perhaps, a little pointless since those who concern themselves with the problem of other minds are concerned with this problem in so far as other minds are understood to be constituted by states, episodes, or processes that cannot be seen (touched, tasted, or smelled) by others. I n other words, if it is permissible for me to say, and to say truly, that I can see your disappointment (and to mean by this not simply that I can see that you are disappointed), then your disappointment, or that much of it that I can see, is not relevantly involved in your having a mind as this is understood in the philosophical problem of other minds. Thoughts and feelings are the most often cited elements of a mind as the mind is understood in this problem, and these are precisely the sorts of things that it becomes most implausible to say are seen by other people. We say that we can see how a person feels, see what he is thinking (or that he is thinking), but not the thoughts and feelings themselves (even here, though, there are exceptions). I will assume, therefore, without further argument that the elements that constitute a person's mind, whatever their exact ontological status (states, episodes, processes, events), are elements that others cannot see. Unlike his arm, or the movement of his arm, both of which can (under normal circumstances) be seen, his anger (or his feeling of anger) and the change in feelings cannot themselves be seen. This is how the problem of other minds is generally understood and, therefore, how I propose to deal with it. But where does this leave us ? Can we conclude, as suggested above, that since we cannot see his feelings, it is more difficult (impossible?) to see that he has feelings than it is to see that his arm is bent or that his hands are trembling? Is it true, as this line of argument seems to assume, that if V is visible (we can see V) but N is not, then there is a more significant epistemological problem in knowing whether N is present than there is in knowing
whether V is present? Surely some such principle as this is being taken for granted in such discussions. If the fact that we cannot see a person's thoughts is relevant to the problem of other minds, it must be because our inability to see his thoughts represents some special obstacle to our seeing that he is thinking. According to this principle, if I cannot see your pain, then I am at some special disadvantage in seeing whether you are in pain or not since your being in pain involves your having pains (which I can't see). Will such a principle as this withstand scrutiny? I think not. Consider the following story: T h e Martians and the Earthlings are at war. T h e Martian Chief of Staff decides to send spies to Earth to discover, if possible, the Earthlings' strategy. Technologically more advanced than the Earthlings, the Martians have the wherewithal to conceal their presence among Earthlings in two different ways. They can alter their appearance so as to look and behave exactly like Earthlings or they can make themselves totally invisible. There is, however, a difficulty associated with the latter alternative. I n the process of inducing invisibility, an intense magnetic field is generated. An invisible Martian attracts, rather forcibly, all ferrous objects within a radius of a dozen feet. T h e problems this creates (in terms of simple maneuverability) are enormous, of course; within a few moments (in the wrong environment), a revealing cluster of paper clips, pins, pencils, buttons, and other loose objects betrays our Martian's location. T i n cans clatter as he moves. Not surprisingly, the Martian Chief of Staff elects the first alternative: his spies will remain visible. His decision is prompted by the desire for concealment. I n order to avoid detection he chooses to send visible spies. Given his limitations, the only way he can create a genuine epistemological problem for the Earthlings is to let them see his spies. T h e point of the story is simply that one must be careful in drawing epistemological consequences from the fact that something can, or cannot, be seen. T h e fact that Vs can be seen and N s cannot does not mean that it is simpler to see that Vs are present than it is to see that N s are present. T h e visible Martians were most difficult to identify; though the Earthlings could see the Martians that were present, they could not see whether they were Martians-see that Martians were present. Whether or not something can be seen is, logically speaking, quite unrelated to the ease with which we can visually detect and identify it. Counterfeit bills can be seen as easily as the genuine article; this doesn't make
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it any easier to see that we have been given a counterfeit bill. Everyone agrees that my aunt and my cousin are visible, but no one thinks this of any help in seeing who my aunt and my cousin are. Air is invisible; yet we see when it is getting windy or that the wind is bending the willows. Can we see such things as weight, heat, and age? However one chooses to answer this question, the answer (even if negative) does not affect the ease with which we can see that she is old, it is hot, and he is overweight. T h e question to ask in regard to the epistemology of these matters (and I am assuming that the problem of other minds is an epistemological problem) is not whether we can see other people's feelings and thoughts; for the answer to this question is irrelevant to our problem. T h e question to ask is whether there is any special difficulty in seeing how other people feel, or that they feel angry, depressed, nervous, distracted, or happy. T h e feelings and thoughts of another person may, after all, be similar to our invisible Martians in at least one respect; though they cannot be seen, it is easy to detect their presence. T h e feelings and thoughts of another person may enliven their appearance (modify those parts of the person that we can see) in much the characteristic and easily identifiable way that our invisible Martians animated the metallic environment in which they entered. This, though, brings us to the second line of defense for those interested in nourishing a problem of other minds. Let us grant (they may say) that other people do have thoughts and feelings; let us even grant that (often enough) a person's thbughts and feelings are 'revealed' in his appearance and behavior. T h e fact remains that due to the perceptual inaccessibility of the thoughts and feelings themselves, we have no way of establishing that that, in fact, is what is being 'revealed' in a person's appearance and behavior. If I raised a red flag every time, and only when, I had a pain in my big toe, thus 'revealing' or 'manifesting' the presence of this pain, this would not help others to tell whether I had such a pain or not, not unless they could somehow establish the fact, or at least make it reasonable to suppose, that there was this reliable correlation between my flag waving and the pain in my toe. But this (the argument goes) is exactly where the problem lies. Only I can tell whether the correlation exists. All others can see is the flag waving. They have to take my word for the existence of the pain, but my word is, from their point of view, simply another bit of flag waving which they have no reason (evidence) to suppose correlated with the relevant feelings. For others to
know that I have a pain in my toe, to see (by my frantic flag waving) that I have such a pain, they must surely have some reason (at least) to suppose that my flag waving constitutes a reliable signal or sign of such a pain. But to establish the reliability of this sign they must, occasionally at least, be able to tell when there is a joint occurrence of the pain and the flag waving; and this, apparently, is exactly what they cannot do since they have no way of knowing about the pain other than via the very correlation (between flag waving and pain) whose validity is in question. This way of putting the problem of other minds is useful because it reveals how exactly the same problem arises with respect to everything we normally (say we) see to be the case. I t also suggests the curious paradox that attends any attempt to analyze our knowledge of the world around us. T h e paradox-call it the paradox of mediate knowledge-can be put as follows: either P is the sort of thing that can be known immediately (non-inferentially, directly, with no evidential basis) or it is the sort of thing that can't ,be known at all. For suppose P is the sort of thing that is known indirectly-on the basis, say, of Q-states. If P is to be known on the basis of a Q-state, then a Q-state must be a more or less reliable sign, indicator, or symptom of a P-state, and this fact must itself be known or, at least, reasonably well established. But the fact that a Q-state is a reliable sign of a P-state can never be known. We can never know this because we can never determine whether a P-state exists when a Q-state exists since a P-state is not (by hypothesis) directly knowable, and to know that it exists indirectly is to know that it exists on the basis of a Q-state which assumes the validity of the very correlation that is in question. Since we cannot tell whether P exists except via Q, we have no way of telling that the correlation between P and Q is as we must assume it to be in knowing that P is the case on the basis of Q. Therefore, P cannot be known even on the basis of Q. Without (at this time) questioning the soundness of this line of argument it should be noticed how the problem of other minds falls into this pattern. One begins by assuming (for whatever reason) that our knowledge of other minds is mediate knowledge, knowledge based on something else (behavior or bodily appearance). I t then emerges that the correlations between behavior (Q-states) and mental state (P-state), the correlations that we must have if we are to know anything about another's mental state, cannot themselves be known to exist since one side of the correlation (the mental state side) can never be known to exist except on the
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assumption of those very correlations whose validity is at stake.2 This is how the story goes with other minds, but the very same story has been told about ordinary objects. Once we ask the question, "How do we know that there are tables and chairs ?" we are already well into the paradox. For the temptation (an unavoidable temptation for most empiricists) is to offer an answer to this question that makes our knowledge that there are tables and chairs into mediate knowledge, knowledge that we possess on the basis of something else (e.g. the way things appear to us). T h e moment this is done, however, we have the same problem we had with other minds. Once again, we are epistemically cut off from establishing those correlations (the correlations between how things look and how things are) that are essential to knowing how things are in this indirect way. If we can know directly that there are tables and chairs, we don't have to establish the correlations between the way things appear and the way things are; but if we have to establish these correlations in order to know this indirectly, then we are prevented from doing so by the inaccessibility of one term of the relationship (the term that we cannot directly know). Perceptual knowledge, our knowledge of the past, and our knowledge of the future all come under the cloud of this argument. This is why I say that the problem of other minds is not a special problem in epistemology. I t is merely an instance of the paradox of mediate knowledge. T h e problem of other minds is a legitimate epistemological problem, not because minds are curious things our knowledge of which involves special difficulties, but because our knowledge of other minds is, like almost all our knowledge, the sort of thing that, upon inspection, seems to be based on something else. At least our attempts to analyze this form of knowledge (as our attempts to analyze most other forms of knowledge) seems to inevitably result in exhibiting it as a type of mediate knowledge. When this happens we get the problem, the same problem in every case. How can we know something indirectly when knowing it in this way seems to presuppose (in our rational assurance about the requisite connections or correlations) that we can know it directly? Knowledge is a patient that we seem to kill every time we operate. There is, of course, something special about the problem of other minds, but what is special has nothing to do with the problem of other minds. People are (presumably) conscious of their own thoughts and feeelings; hence, someone is directly aware of those things the existence of which constitutes a problem for others.
This means that although everyone has a problem about something, there isn't anything about which everyone has a problem. This distinguishes the problem of other minds from the problem, say, of how we know that there are physical objects. But the fact that I know that I am in pain (directly and non-inferentially), or that others know, in the same immediate way, that they are in pain, is irrelevant to the problem of other minds. For the problem of other minds is the problem of other minds. That others know that they have thoughts and feelings is as irrelevant to how I know it (and this is the problem of other minds) as would be the fact that God knows everything to the problem of how we know anything. That God knows everything, directly and noninferentially, neither helps nor hinders me in coming to know anything; it is, for epistemological purposes, an irrelevant fact. Similarly, the fact that you know you are angry, and that you know it in a special direct way in which I can never know it, is (even if true) irrelevant to the question of how others can know that you are angry-irrelevant, that is, to the problem of other minds. A second feature of the problem of other minds that misleads philosophers into thinking that there is something special about it is, I think, the confusion discussed earlier-the confusion between seeing something and knowing something (or, if you will, between visibility and knowability). Since his frown is visible and his anger is not, the fact that he is frowning is (mistakenly) thought to be epistemically more accessible (so to speak) than is the fact that he is angry. There are supposed to be fewer epistemological barriers between us and the fact that he is frowning than there is between us and the fact that he is angry-hence, the problem of other minds represents a higher order problem. This, though, is a confusion that we should now be in a position to avoid. T o be told that Vs are visible is to be told nothing about whether the fact that this is a V is known (or knowable) directly, indirectly, or not at all. T o be told that N s cannot be seen, but Vs can, is definitely not to be told that our way of knowing that something is N is more indirect, less immediate, than our way of knowing that something is V. As a more or less abstract illustration of this fact consider the following: the visible piece of behavior, B, , is (visually) indistinguishable from the visible piece of behavior, B, . B, and B, are like twins (visible but indistinguishable). Suppose, furthermore, that whenever B, or B, occur the invisible state M is present. I n this situation, although B, and B, can be seen, and M cannot, one can (or could if certain other conditions were
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satisfied) see that M was present without being able to see whether B, was present and without being able to see whether B, was present. None of this is to deny that, in seeing how other people feel, we rely in great measure on their (visible) behavior and appearance. What some people fail to appreciate, however, is how much of a two-way street this is, how often we see what physical states are present by means of the mental states that are present. I n watching her read the letter we might see, by her alarm, that the letter contained bad news; see by her joy that he is coming; tell by a person's lack of interest that there were no pretty girls at the party; tell by his detailed knowledge of the city that he once lived there; and tell by a person's enthusiasm that cocktails are about to be served. T o use our former example, it is not (I think) too preposterous to embellish the story by saying that the clever Earthlings finally managed to detect the (visible) Martian spies by means of their (the Martians') quick wit, detailed knowledge of Martian history, ignorance of Earth history, and warped sense of humor. I n this fanciful case it is easy to see that invisible M s (Martians) are present, hard(er) to see that visible M s are present, but still possible to tell that the visible M s are present by means of their non-visible N s (humor, wit, knowledge). Two final words: it may be objected, rightly I think, that our ordinary talk about seeing that others are angry, depressed, bored, and so on does not so much describe the way we come to know that others are endowed with a mental apparatus similar to our own as it presupposes it. We see that he or she, this person or that child, is bored, interested, or depressed-thereby coming to know, not that they are conscious human agents with thoughts and feelings, but that these conscious human agents (or what we take to be such) are, in particular, in a certain mental state. I n saying that I can see that Johnny is delighted I am not describing the way I have discovered that Johnny is the sort of thing that can have experiences of that sort. I think this is certainly true. Our ordinary talk about what we see does, in large measure, presuppose that others are minded; it only purports to describe the way we come to know that persons (minded bodies) are in specific mental states. Once again, however, this leaves us in a position exactly parallel to our knowledge of physical objects. Most of our talk about objects, about what we can see to be the case and what we have discovered to be the case, presupposes that there are such objects. What we routinely describe ourselves as coming to know is not
that there are such objects, but that these objects have certain properties and stand in certain relations to each other. I n seeing that the page is torn, that the ground is wet, that his arm is moving, and that there are still some cookies in the jar, I have not described a perceptual achievement which has taken me from ignorance to knowledge of a physical world. I have, rather, described a perceptual achievement that has taken me from some knowledge (or presumed knowledge) of the world to a more specific and detailed form of such knowledge. I n the case of other minds we proceed in exactly the same way. Secondly, it should be remarked that I do not suppose it a simple matter to see when someone is bored, nervous, exhausted, in pain, deep in thought, and so on. Nor do I suppose that when we do see that these things are so, we rely exclusively on the way the person looks and behaves. Being angry, embarrassed, ashamed, or guilty (i.e. feeling guilty) may involve a great many things (including, perhaps, social factors), and to see that a person is embarrassed (not, say, ashamed) may be quite a sophisticated achievement involving a good many more things than simply how he looks or behaves. But the same could be said about some of the physical states that we see to be the case. I t is not just the way the iron looks that enables us to see that it is magnetic, not just the way the ladder looks that tells us it is over twenty feet, and not just the way the pen looks that enables us to see that it is out of ink. Seeing what is so may not be easy, but whatever the difficulties, they don't seem to be concentrated in the area of other minds.
This is another way of saying that the analogical argument for other minds, in so far as it relies on premises describing the content and character of the physical world (features and behavior of other bodies), begs the question. For the epistemological problems inherent in knowing that he is angry are already present in knowing that his fists are clenched and his face is red. The argument by analogy is simply a means of trying to establish the credibility of such a correlation on the basis of a single case-one's own case. I will not here take the time to review the reasons I reject this argument as a satisfactory solution to the problem of other minds (but see note 1).
