A Disproof of Other Minds
We can’t prove the existence of other minds, but can we disprove their existence? Can we construct a plausible argument that other minds don’t exist, only one’s own mind does (solipsism)? That sounds improbable and I don’t know of any attempt to do it, but philosophy is full of surprising arguments that at least seem to establish improbable conclusions (we call them paradoxes). The exercise is worth undertaking, even if the outcome is that no such argument can be produced; we might discover why such an argument is impossible. In fact, I think we will find the journey illuminating and the destination reachable (notice how cagey I am being). There are also real theoretical benefits to the conclusion in question; it gives us a new metaphysics and accompanying epistemology. It’s worth a try anyway.
Let’s begin with a bad argument, though one rooted in widely accepted principles at one time. We will start to see a structure emerge. Thus: the existence of other minds is unverifiable; what is unverifiable is meaningless; therefore, it is meaningless to say that other minds exist; so, they don’t. The argument is not as hopeless as it may sound in this post-positivist age: for it is not an absurd premise that every meaningful claim must be backed by a possible human experience (have empirical content). Even the most speculative ideas of physics are connected to possible types of experience, e.g., seeing atoms or the big bang or curved space. We know what it would be to have such experiences, though they are impossible in practice. But in the case of other minds, we have no idea what it would be like to experience another mind, e.g., what it would be like for me to experience your mind; certainly, I can’t introspect another mind (human or bat). It may thus seem that I have no real concept of another mind, just a kind of empty place-holder (“the cause of this behavior”). What could be more perceptually inaccessible than another mind? The belief in other minds would appear to be inconsistent with a plausible empiricist principle, viz. that intelligibility requires possible perceptibility. Other minds are just too cut off to permit adequate conceivability; they contrast markedly with one’s own mind in this respect. Wouldn’t it be nice, theoretically, if there were no such things? Then we wouldn’t have to countenance the radically unknowable in our ontology. There would be no skeptical problem, because there is nothing out there (or in there) to know. It’s like ghosts and round squares—these things are not conceptually capturable.
Here is a second type of argument for the desired conclusion; it hinges on countability. Suppose minds are immaterial substances; then there is an individuation problem. How many such minds are there—what is their criterion of identity? We can’t appeal to position in space because immaterial substances have no extension and location in space. What counts as one or twenty or 1,137? Where does one leave off and another begin? We have no clue. Therefore, the ontology is shot, wonky, or otherwise unquantifiable over. The phrase “immaterial substance” is not a sortal predicate with an attached criterion of identity; so, there are no such things. We might hope to escape this embarrassment by dropping the immateriality claim, but that doesn’t really help, since there is a countability problem anyway. The word “mind” is itself not a genuine sortal: how many minds are there in the world? What about unconscious minds and divided brains and split personalities? We can count brains (or we think we can) but we can’t count minds; the word “mind” is just a useful way to sum up talk of mental states—there is no entity here that can be clearly individuated and enumerated. Or so it might be claimed. Accordingly, talk of other minds is not talk of a collection of discrete objects with a determinate cardinality; therefore, there are no such things. It’s like asking how many gods there are or fictional characters or sakes. Notice, however, that this argument carries over to one’s own mind—with what right do I say that I have but one mind? So, we don’t get solipsism out of this argument, only rejection of the ontology of minds in general (many or one). We would do better to come up with an argument that rules out other minds but not one’s own mind. Still, we can see how an argument might be constructed; we are not as engaged on a fool’s errand as might have been supposed.
Now we come to the argument that prompted this mission impossible. I warn the reader that it will not be simple or easy to understand or clearly sound; but it bears thinking about and has a kind of spooky appeal. I have never heard of anything like it. First, what is its general shape? As follows: if there were other minds, there would be other worlds to go along with them; but there is only one world; therefore, there are no other minds. There is only my mind and my world, i.e., solipsism is true. The argument is clearly valid, so it must be the premises that are at fault, if anything is. What do they mean? The first premise means that for any mind there is a world that is for that mind—corresponding to its way of seeing and feeling things (Umwelt, Lebenswelt). For me, that world is a certain place, a certain set of activities, assorted objects, etc.—what reality is as far as my life is concerned. It is quite specific and full-blooded—the world as I experience it. This world is my world, and my world is not your world. It is the world as it exists for me—the manifest image, the lived environment, the given, the phenomenal. This is the original and correct use of “world”–as in the world of theater or tennis or the human world. It is not an inhuman universal abstraction. Worlds in this sense vary from creature to creature and may contradict each other. They are plural and subjective (in one sense). The second premise is that there can only be one real world—the world of objective reality, as we say. Reality isn’t plural; it is singular—the way things uniquely are. There are not as many objective realities as there are lived subjective worlds. But then, these worlds cannot be the real world, which is singular; so, they cannot really exist (they must be merely apparent). It follows that the minds that have them also do not exist, since minds entail them. There cannot be minds without worlds they inhabit. But I know for sure that I have a mind, which has a world; so, that must be the real world, the one true reality. My world exists and it is the world; the others don’t exist, on pain of objective plurality. We avoid fragmenting the world by denying the existence of other minds.
Hold on, you protest, you are moving way too fast! Why not say that the real world is none of the individual worlds that accompany minds? It is the world of science, especially physics—that denuded mathematical world we have been taught about since the seventeenth century (primary qualities, invisible atoms, peculiar forces, colorless matter). The trouble is that this is no one’s world; it is not a “world” at all. And it produces all manner of conundrums and obscurities: can we really conceive it, is it knowable, how does it relate to the ordinary world we live in and with? This is an old story and I won’t repeat it. The point is that we can avoid all that mumbo-jumbo by a simple (though drastic) move: pick my world as the world that really exists. But this requires us to deny other rival worlds, those that are tied to other individual or species minds. We can’t say there are as many worlds as minds, because there is only one world, and we don’t want to go down the road to the puzzles of a world that is for no one (the world with no name); so, we opt for solipsism. There is only me and my world. There may be other beings just like me physically (robots), but they don’t come equipped with worlds, because they have no minds. My world is the real world; there are no other worlds of other minds to compete with mine. Thus, we prove that there are no other minds: it makes the best sense of reality as a whole. In fact, the idea of a neutral world that is a world for no one is a comparatively recent innovation, invented to provide a philosophy for the new mechanistic physics and has no more authority than that. It is not unquestionably sound metaphysics. Naively, we take our individual world as reality, and only the believed existence of other minds makes us doubt that we are in daily touch with that reality; reflection then suggests that other minds would undermine this naive point of view—the solution is to jettison them. If the choice is between an unintelligible reality and solipsism, we should choose solipsism. Or to put it more simply: my world is real, so there cannot be other worlds that contend with mine for the title. I am the arbiter of reality, not other minds that I have no reason to believe in anyway. There cannot be other minds because my reality is reality, according to solipsism. And note that this is not a form of idealism, since nothing has been said to suggest that my reality is all in my mind; it consists of things just as I naively think of them (including being able to exist unperceived). But this takes us into the epistemology and metaphysics of what may be called solipsistic realism, the subject of another paper.
The aim was to produce an argument for solipsism, in particular the non-existence of other minds. Of course, the argument has premises, none of which is self-evident. These premises are however not question-begging and call upon substantive intuitions and principles. One point has been the misuse of the word “world” in philosophical discussions (a world is always someone’s world); another has been a reliance on the dubious idea of an etiolated abstract “world”. The denial of other minds is supposed to rectify these problems. And did we ever really believe in other minds anyway—in the way we believe in the existence of our own mind? Don’t people just act as if other minds are real (they have this belief drilled into them without ever having been given a solid proof of it); other minds are inherently indemonstrable. This is why it has been easy for people to believe that other “inferior” people and animals don’t have minds as they do. Certainly, other minds don’t compete with my mind for epistemological authority (evidence). In the end, it’s just a hypothesis that might turn out to be false; and now we see that it is (arguably) false. The existence of other minds threatens the existence of the external world (singular), so we are better off without them. Things are so much simpler that way. The real world is simply this.
