Other Bodies
Other Bodies
The orthodox view of our knowledge of minds is that while other people’s minds are doubtful my own mind is not: I can be certain of my mind but not of other minds. Hence there is a skeptical problem of other minds but not of my own mind. There is a deep epistemological asymmetry between self and other. However, it is not thought that there is a comparable asymmetry with respect to the body: the existence of other bodies is doubtful, but so is the existence of my body. I might be a brain in a vat with no body, and other people’s bodies might be hallucinations; there is a skeptical problem about both. Now that I don’t contest, but it doesn’t follow that there is no epistemological difference between my knowledge of my body and my knowledge of other bodies. I could be more certain of my body than I am of other bodies, and the ground of my knowledge might be different in the two cases. So, let’s explore the question. How do I know other bodies (human, animal, and inanimate)? I know them by sense perception, notably vision. But sense perception is subject to illusion and hallucination, so that source of error has to be recognized. How do I know my own body? By sense perception, to be sure, but also by direct knowledge of what I am doing, by proprioception, and by sensation (feelings in my body). So, I have more evidence about my body than I have about other bodies—more to go on, more to appeal to. Moreover, I don’t have hallucinations of my own body as I have hallucinations of other bodies—I never have impressions of my body existing when it does not, as I have impressions of other bodies existing when they do not (as when I have a false impression of someone lurking in the dark, etc.). Also, I am always (when awake) aware of the condition of my body, even when I can’t perceive it with my five senses, but this is not true of other bodies. I can’t have proprioception of other bodies, but proprioception of my own body is ever-present and highly reliable. All in all, I am in a solid position epistemologically with respect to my body: I know my own body remarkably well, even if I can’t be certain I’m not a brain in a vat. It’s really the best-known physical object in the world as far as I am concerned. I would venture to suggest that the probability of my body existing is a good deal higher than the probability that other bodies exist. I am more ready to accept body solipsism than the hypothesis that other bodies exist but mine doesn’t. I’m pretty damn sure my body exists! Yours, well, that’s more a matter of speculation, faith, received wisdom. Every night I dream of bodies that don’t exist, but I never dream of my own non-existent body. But is this something I can defend against a determined skeptic? Actually, no, except to a limited degree, but this degree marks a difference between my body and yours. For I can argue that I must at least have a brain, while your brain is up for grabs. This is because I know with certainty that I have a mind, and my mind needs a brain; but I don’t know with certainty that you have a mind, so I can’t infer from that that you must have a brain. I can’t move from knowledge of your mind to the conclusion that it is housed in a brain, because I don’t have that knowledge; but in my case, I have indubitable knowledge of my mind, so I have a solid basis for the move to a brain. Thus, I have a Cogito-type argument for a body part belonging to me, but I have nothing comparable in your case—you could be all hallucination as far as I am concerned (though not as far as you are concerned). There is no Cogito-type argument of the form “I think, therefore you have a body”, but there is such an argument as “I think, therefore I have a body”—where the body I have perhaps consists just of a brain. Can I infer the existence of any bodies other than my own from the existence of my body (even if that is just a brain)? In the case of the mind, that looks to be infeasible: I can’t infer from the existence of my mind that any other minds exist or ever existed or will exist (solipsism-of-the-moment is inescapable as a skeptical possibility). But in the case of the body the prospect of other bodies looks brighter: because I can infer from the existence of my body that other bodies didand will exist. The reason is that the matter of my body did once belong to another body and it will later come to belong to a separate body too. The matter of my body moves around composing different bodies at different times, but the “matter” of my mind does not. Thus, my bodily matter survives my body’s demise, as it once survived the demise of another body or bodies; but my mind does not likewise persist through time—it is limited to me. So, I can know that other bodies once existed and will exist, given that I know that I have a body—not so for mind. This thinking thing might be the only thinking thing that ever existed or will exist, but this extended thing is one among many extended things spread out in time—that is its nature. I can assert “I am an extended thing, therefore there must be other extended things (at some time)”, assuming that a past and future exist during which my matter exists and my body doesn’t. My body implies other bodies (on reasonable assumptions) but my mind doesn’t imply other minds; and this point applies equally to my brain alone. (But, of course, I can’t infer that your body exists in this way, since your body is not composed of the matter that composes mine.) In short, I know more about my body than I know about your body; so, I have more of an other-body problem than a my-body problem (though I do have somewhat of a my-body problem). It is true that I cannot be certain that I have a body just as I experience it, but I can be certain that I have some sort of body (even if it’s just a brain quite unlike the one I think I have). However, I really can’t be certain that you have a body of any kind, since you might just be a figment of my imagination, an outright hallucination. Accordingly, it is too simple to say that there is no epistemological asymmetry between my knowledge of my body and my knowledge of your body: I am better placed to know my own body, and in several ways.[1]
[1] In the Matrix people hallucinate their body and are quite wrong about what it is up to, but they can’t hallucinate the fact that they have some sort of body, since that is a precondition of their having a mind at all. But there is no conceptual bar to hallucinating other people’s bodies in toto; they need not have any physical reality at all.
As you say, we have access to additional sources of information about our own bodies (eg proprioception) that we don’t have about other bodies. So we have access to more information of a qualitative type (not just quantitatively more). Can we say the same about our minds vs other minds? As far as thoughts go, we have quantitatively more information about our own, but do we have qualitatively more? If thoughts can be communicated, then it would suggest we don’t. We have feelings, intuitions, etc obviously which are private and not shared. (We don’t feel the pain or sadness of others, though we may empathise.) But is it the case that the private aspects of these sensations are the body based aspects, while the mental aspects can be shared? Or is it too hard to cleave body from mind in this way? What about the experience of knowing (the kind of direct knowledge one has when say one recognises a pattern)? Does that experience depend on a body based sensation in any way?
In the case of minds we can’t be sure there are other minds, though we can be sure we have a mind.
It seems to me (as an outsider) that philosophers are constantly on their back foot when dealing with solipsism. I assume this is because they believe that the existence of mind is the only thing of which one can be sure. And what’s worse, the solipsist can always retort that there is no observation one can make that is inconsistent with their view, so, if restricted to purely logical (rather than pragmatic or ethical) grounds, why not use Occam’s razor and embrace solipsism.
But, logically speaking, isn’t the state of being sure the thing we can be most sure about as all other phenomena, observed, remembered, felt and thought, could have been generated by who knows what? (Perhaps one day GPT will be integrated into our streams of consciousness, and we will not be able to tell our own thoughts from its generative activities …) Can the true skeptic really be sure they are thinking or feeling ticklish, or is that just something they have made themselves sure about?
To the extent that one wants to posit the existence of anything beyond a state of being sure (such as the mind or body), how could one be sure that being sure is purely mental, and does not involve the body?
To be sure implies a simultaneous recognition of and a decision regarding. Recognition is a felt experience that could be described as both a bodily sensation and mental. Decisions are actions, so presumably require extension of some form in which to manifest, as well as time, and a subject and object (even if only transiently constructed). On what grounds can one say decisions are not just as much activities of the body (nervous system, what have you) as the mind?
As a purely speculative question, is it logically possible, or is there any reason to disbelieve, that one could “recognise and decide” that in “being sure” one’s ability to “recognise and decide” is subsumed neither by mind nor body, but spans both? Why would this be less believable than it being a purely mental activity?
You are describing Cartesian philosophy not what philosophers in general believe. It would be generally agreed that mental states could have a bodily expression, and many would suppose they must have. Being sure would not be uniquely certain; one would also be sure one is doubting something. Solipsism is hard to refute.
I hadn’t thought about it before, but being sure is not symmetric with doubting. I can neither doubt I am sure, nor doubt I am doubting. I can never really be consumed with doubt, since if I am doubting, I can be sure of that. (If I feel consumed with doubt, it is just I have forgotten I am sure I am doubting.) Doubting depends on being sure in this sense. (Though it is a bit of a mystery to me what doubting is – it seems analogous to the breaking of a circuit, that isn’t fully broken.) The capacity of deciding with certainty seems to rely on nothing other than itself. Is there more to being self-conscious than having the capacity to “decide on one thing”? One might argue consciousness that enables experience is more basic – but I think that is a statement of a qualitatively different character, like stating the physics/chemistry of life is more basic. It relies on placing ourselves in an empirical evolutionary context, and assumes we evolved from animals that were conscious but didn’t have the capacity of being sure (which I am not saying is wrong, or right, just a statement of a different kind).
You have rediscovered Descartes: I cannot doubt that I am doubting, so even when I try to doubt everything I find a certainty.