Sexual Knowledge

 

 

In endnote [A] to An Enquiry Concerning Human Understanding Hume asks: “I should desire to know, what can be meant by asserting, that self-love, or resentment of injuries, or the passion between the sexes is not innate?” He clearly thinks that these “ideas” (Locke’s term) are innate, so that they are not learned by experience or instruction. In particular, sexual passion is present innately, though it may not reveal itself until well after birth. We should not suppose that Hume means only some kind of non-cognitive drive for sex: he must mean that the affective-cognitive package of sexual passion is innate, including certain kinds of knowledge. Sexual passion includes the desire to do various specific bodily things, so it will involve some kind of mental representation of these things. It will involve knowledge of what to do sexually—what goes where, and so on. Thus some conception of the anatomy of the object of this passion will be installed in the mind prior to all experience. In short: sexual knowledge is innate.

            Presumably this thesis will not be disputed in the case of animals. It is hardly to be supposed that dogs and cats, to take only the animals most familiar to us, learn how to have sex by means of observation or instruction: they are not in the dark about the mechanics of sex until they see other animals doing it or receive a “sex talk” from their elders. No, they know instinctively what to do—which is just what you would think the genes would program. Just as cats know instinctively how to fight and groom, so they instinctively know how to have sex. And not only the sexual act itself but also what leads up to it and what may follow it—they also know innately how to court and parent. This knowledge lies dormant till maturity, but it is encoded in the genes nevertheless. It is as instinctive as eating and breathing, walking and sleeping. Animals must have an innately fixed mental model of the opposite sex’s anatomy along with an action plan to guide their behavior. This innate system will be species-specific: cats and dogs don’t have mental representations of the anatomy of elephants or reptiles. They have a dedicated module for sexual activity equipped with suitable cognitive structures. Compare the human language faculty: a species-specific modular mental structure present at birth. This is just what you would expect given the importance of sexual know-how right off the bat (what would happen, or not happen, if an aroused animal had never observed an act of intercourse and had no innate knowledge of what it involves?).

            Plato, Descartes, Leibniz, and Chomsky didn’t consider sexual knowledge, preferring to talk about knowledge of mathematics or grammar, but it is clear that they would agree with sexual nativism.  [1] Poverty of the stimulus applies here, as well as uniformity within a species, brevity of the learning period, spontaneous emergence, etc. Also there is a complexity to sexual knowledge that is easy to miss: it is not just a simple matter of stimulus and response. When animals mate they have to negotiate each other in all sorts of ways, conducting an elaborate series of actions leading to a specific goal, preceded by appropriate courtship (think bower birds). The actions involved are not simply elicited by impinging stimuli but are carefully controlled by perception of the prevailing circumstances, involving knowledge of fertility and the correct way to mount and be mounted, as well as what to do once coitus is complete. As parenting is a highly structured activity, so is copulating. Neither is simply the mechanical product of randomly impinging stimuli. I am sure that if animals were artificially prevented from observing the sexual behavior of other animals they would still know how to have intercourse when the time is ripe. So we should add sexual knowledge to the list of other things now generally considered innate; and perhaps it could serve as the basic model for the nativist position, given its obviousness (compared to ethical knowledge, say).

            Returning to humans, picture Adam and Eve: they have never heard of sexual intercourse and certainly never observed it in others. No one has ever taught them about the birds and bees. According to the empiricist, they know nothing of sex and are clueless about how it should be performed—as they are ignorant of tennis and how it should be performed. According to the nativist, they are already equipped with sexual knowledge (God would not leave them sexually ignorant, given the importance of reproduction for the human race). They innately desire sex and they innately know what to do to satisfy that desire—no need to experiment with various bodily entanglements in a process of trial and error. Genital pleasure will certainly offer them some guidance, but it will not by itself be sufficient to explain their sexual behavior, since they need to know how the genitals are combined in sex. There will necessarily be a cognitive dimension to this, presumably involving mental models of the other’s body and which parts do what. God will equip them with this knowledge, so as to prevent much blundering and potential injury. Adam and Eve were created already in possession of sexual know-how (which involves a good deal of know-that). Let us then suppose that they possess a specific schema or module or data structure dedicated to sex located somewhere in their brain, alongside similar centers for language, mathematics, ethics, and whatever else you deem innate. They possess an innate sexual faculty alongside other innate mental faculties.

            Now my question is this: how extensive is this faculty? How much sexual knowledge is innate? Is there knowledge of the various possible sexual positions or the various kinds of foreplay? I doubt it, but that is not my chief concern, which is this: do humans have innate knowledge of the connection between sex and reproduction? Do they know instinctively that sex produces babies? Certainly the sentence “Sex causes babies” is not analytic—there is no way to reason from propositions about sex to propositions about babies. It is entirely possible to be ignorant about the origin of babies while being well informed about the mechanics of sex. It is an a posteriori empirical fact that sex leads to babies. I suggest that people don’t innately know that sex and reproduction are connected; they learn this from experience, just as the empiricists say. And they may not learn it—they may remain ignorant of the connection. Consider animals again: I conjecture that no animal has ever grasped the sex-baby connection. Animals innately know how to have sex and how to take care of babies, but they don’t know—innately or by experience—that sex results in babies. To know that requires fairly sophisticated empirical enquiry concerning the time period of pregnancy as well as acceptance of something quite surprising. I suspect that even our most intelligent cousins in the animal world find the origin of children a mystery, if they think about it at all. Babies just appear from nowhere as far as they are concerned (how on earth did they get inside the mother?), even though they have knowledge of the activity that in fact produces them. (Indeed, I doubt that animals ever wantoffspring at all, though they clearly do want sex.  [2]) When did it dawn on our ancestors that sex produces babies? Did Neanderthals know about the sex-baby connection? Are there any “primitive tribes” today that don’t grasp the connection (thinking that babies are implanted by the gods and that sex is just good fun lacking any causal connection to reproduction)? This is why it is possible to convince children that the stork brings babies—because they don’t know otherwise (try convincing anyone that sex is performed with the ear and the little finger and see how far you get!). So some sexual knowledge is innate and some is acquired. Well and good: it is the same with knowledge of language–some is innate and some acquired. It is an empirical question where a given piece of sexual knowledge falls; there is no logical necessity here.

            But now there is a puzzle: why is this kind of sexual knowledge not innate? You would think that the genes, concerned above all with promoting reproduction, would program knowledge that sex leads to children, so that animals would do what is necessary to create children (new bodily vehicles for genes to nestle in). Their practical reasoning would take the form: I want babies; sex leads to babies; therefore I want sex. But this is not how it works (notoriously and tragically): animals and people want sex and as it happens sex leads to babies. Animals don’t have sex in order to produce babies; they have sex in order to have sex. But why didn’t the genes at least let us know that sex produces babies? They gave us other kinds of sexual knowledge, but they kept us in ignorance of this central fact about sex. We know innately that the penis and vagina are involved in sex, but we don’t know that children are—unless by experience.  Why don’t at least some animals know this? It’s almost as if the genes were keeping this piece of information from us! They don’t want us to know that sex leads to babies, but they very much want us to know how to have successful sex (by “us” I mean all animals).

Here an obvious thought comes to mind: the genes don’t want us to know because it might deter us from doing what they want us to do. If animals were well aware that having sex would lead to becoming parents, they might be less inclined to have sex. That is surely true in the human case, but from a gene-theoretic perspective it makes sense for all reproducing animals: animals are the slave of their genes and their genes keep them in ignorance of what might lessen the genes’ chances of survival. So maybe the ignorance is programmed ignorance—ignorance by design.  [3] The genes have made sex very attractive for animals (I’m thinking mainly of mammals) so that animals will do what the genes want them to, without letting them in on the dirty little secret that sex leads to parenting. We can imagine a species in which the psychology is constructed differently: the animals want to have children but the sex is not particularly appealing, rather like building a nest or burrowing a hole. The genes have designed these animals in such a way that their desires lead to offspring and hence gene propagation, but without making sex attractive and the sex-baby connection obscure. Theoretically this would work to get the genes into later generations, but evidently it has not gone that way on planet earth; the genes here deemed it wiser to opt for attractive sex (along with knowledge of its mechanics) combined with ignorance of its effects. Boring sex might in principle lead to babies in the presence of a desire to have babies, but the genes have in their wisdom opted for enjoyable sex and a lack of knowledge of the sex-baby connection. We must assume they had their reasons. The psychology of sex is therefore not one in which the sex-baby connection plays a role, however important it is biologically: animals don’t have sex as a means of satisfying their desire to have babies; they have sex despite the fact that it leads to babies. At any rate, they operate in ignorance of the fact that sex produces babies. Humans are probably alone in the animal world in grasping this connection, as we are alone in knowing many things of no biological relevance; from a biological point of view, this knowledge is either unnecessary or positively disadvantageous. Genes manipulate their vehicles by means of orgasm and by not letting them know that orgasm leads to parenting. Hence animals have innate sexual knowledge but not innate knowledge of the results of sex: they know the mechanics but not the consequences. There is really no reason for any animal species to grasp the fact that sex leads to babies—the genes can get along quite nicely without ever installing such knowledge, as they did for millions of years before modern humans came along. Thus our sexual knowledge falls into two parts: a necessary part (the mechanics) and an unnecessary part (the consequences)—the former being innate and the latter acquired.

            Socrates elicited knowledge of Pythagoras’ theorem from the slave boy by suitable questioning, thus demonstrating his innate knowledge of geometry. I doubt that questioning alone could elicit the slave boy’s innate knowledge of sex, but the injection of a suitable hormone might have done the job, as it naturally does in the case of adolescence.  [4] However, nothing like this could elicit the knowledge that sex produces babies—for that the slave boy would need either instruction or experience. So nativism about sexual knowledge is partly right and partly wrong: some of it is inborn and some of it is derived from experience. We are certainly not born a sexual blank slate, as Hume observed.

 

  [1] They may have thought it just too obvious to be worth mentioning compared to knowledge of language and mathematics; or perhaps they had a non-cognitive view of the sex instinct. Hume is bringing some solid common sense to the discussions of innateness with which he was familiar, notably Locke’s. Sexual passion is clearly not the result of being instructed to have it, or observing others in flagrante!

  [2] I mean that they don’t formulate the thought that it would be nice to have children and then set about accomplishing that goal—the thought of children probably never enters their heads as they copulate.

  [3] We might compare this with the ignorance of death among animals. They don’t know they will die, either because there is no biological point in knowing this or because the genes have expressly ensured such ignorance (a mutation that produced knowledge of death might make animals with it less reproductively successful than animals without it). Or again, how would it benefit the genes for animals to know that defecation is the result of eating? Animals probably have no idea about this causal connection—and why should they given that it isn’t useful knowledge (unlike knowledge of how to copulate, or fertilize eggs in some other way)?  

  [4] I assume this is the mechanism, simply stated: it is some change in the nervous system that brings the implicit innate knowledge to the fore upon sexual maturity, just as such changes produce sexual maturity itself.

                                               

 

 

Seeing Sensations

 

 

It has been generally accepted that you can’t know what a sensation is like without experiencing it yourself. No experience of pain, no understanding of pain; no seeing of red, no knowing what seeing of red is. Possessing the concept requires instantiating what it is a concept of. This is not true of states designated physical: you can know what measles is without having it, or how a bat’s wing is constructed without having one, or what C-fibers are without having any in your brain. So sensations differ from physical states in this epistemic respect: sensations require having them to know them, but physical states can be known whether you have them or not. But why is this? What is it that makes it the case that there is this epistemic asymmetry? Why is it that I can know what C-fibers are without having any C-fibers but I can’t know what pain is without being in pain (at some time)?

            The answer is crushingly obvious: I can see C-fibers in someone’s brain (perhaps using a microscope), so forming the concept; but I can’t see pain in someone’s brain (with any microscope), so forming the concept. Lacking sensory perception of pain, I have to fall back on acquaintance with instances of it in my own person (I can’t be aware of pain in another person in this way). I have to get the concepts from somewhere, and perception (mainly vision) allows me to get the concept of C-fibers by looking inside brains (or things similar to brains), while the concept of pain cannot be acquired in that way, but must be based on introspection.  [1] I can only introspect myself, but I can perceive many things other than myself. Thus it appears that we can assert the following counterfactual: If we could see sensations, we would know what they are without ourselves needing to have them. Suppose I couldn’t see C-fibers or anything like them, or sense them in any other way: then I wouldn’t know what C-fibers are—they would be like an exotic species I’ve never set eyes on (or heard about from someone who had). They would be an epistemic blank to me. That is our position with respect to sensations: we have never seen bat experiences, for example. Nor have we ever seen our own sensations, but here we have direct acquaintance with them in acts of introspection—as we don’t for bat sensations. But if we could see sensations–as they intrinsically are, as we see physical things–then we would not need to fall back on introspection. The trouble is that this counterfactual looks like it has an impossible antecedent: we necessarily can’t see sensations. This necessity claim is very strong, and even if true applies only to human beings. Is it true that no possible being could conceivably perceive sensations? It is not as if sensations lack causal powers or spatiotemporal coordinates—why should they not be in principle perceivable? And yet it is hard for us to conceive of what perceiving them might be like. That might just be a limitation on the human imagination, born of our particular cognitive faculties; maybe there are logically possible sensory systems that can respond to sensations as ours respond to streaks of lightning or cold air. But even if this is not possible the counterfactual still holds, only now with an impossible antecedent: if  (per impossibile) we could see sensations, then we would know what they are in that way. So this is still the explanation of why we can form concepts of physical states, but not of sensations, without having them: the reason for the asymmetry is that one is perceptible and the other is not.

            Consider a character, Billy, suspended in a tank under conditions of sensory deprivation: suppose Billy has many bodily sensations but no perception of outer objects; in particular, he feels pain but has never seen a brain or anything like one. He knows very well what pain is, since he feels it every day, but he has no idea what C-fibers are, having never seen any, or anything like them. He is an expert phenomenologist but a physical ignoramus. One day he is liberated from his tank and given outer senses: a brain is placed before him with C-fibers prominently displayed and he gazes at it for a good long time. Now he knows what C-fibers are, not having known this before, even though he knew very well what pain is: he has learned something new. Therefore C-fiber firing is not reducible to (identical with) pain: it is something over and above pain. We have thus proved that there is more to the world than sensations: it would not be plausible to maintain that C-fibers are nothing more than pain—or else Billy would have known about C-fibers just by knowing about pain.  [2] Whether or not this argument reaches its conclusion, it illustrates the dependence of certain concepts on perception: these concepts cannot be derived from introspection alone. The reason for Billy’s earlier ignorance about the nature of C-fibers is that he lacked perception of them; and the same can be said for our ignorance of (say) the sensations of bats—we lack perception of them. We only know the nature of our own sensations because we have another route to such knowledge, i.e. introspection. If we lacked introspection, we would have no concept of our own sensations either.

            What if we could know both things both ways? Suppose we could know sensations from our own case andknow them via perception: then we wouldn’t have any problems of conceptual limitation vis-à-vis other types of experience. We could know what it’s like to be a bat without having bat-type experiences. This would open up our knowledge of mind considerably; maybe it would enable us to solve the mind-body problem, by locating the psychological in the realm of perceptible things.  [3] It would certainly involve a conceptual transformation. Similarly, suppose that we could know physical states by perception and know them by introspection: then a lack of perception of them wouldn’t bar us from arriving at an accurate conception of what they are (unlike Billy). One might have a sensation as of one’s C-fibers firing (not the same as a sensation of pain); and this too might contribute to solving the mind-body problem, by locating the brain in the field of consciousness. As it is, the duality of perception and introspection underscores the duality of physical and mental states, but that duality might reflect our epistemic predicament more than any underlying ontology. A perceptual concept for sensations would render sensations more objectively comprehensible, while an introspective concept for brain states would render them more subjectively comprehensible (someone who lacks the C-fiber sensation can’t know what it’s like to have that sensation). As it is, however, we are stuck with a sharp duality of understanding: one thing we understand perceptually, the other introspectively. We are thus saddled with an unbridgeable subjective-objective divide. The point I have wanted to make here is diagnostic: the reason for the divide is that we can’t see sensations. That may be a contingent truth or it may be a necessary truth, but it is why our concepts for sensations are as they are; if we conceived them perceptually, we would have no trouble extending our psychological understanding beyond our own case. Bat minds would be transparent to us—as transparent as their bodies and brains.  I strongly suspect that the limitation here is contingent, though human beings would have to change dramatically (unrecognizably) in order to become mind perceivers: I think there must be beings in possible worlds that can see (etc.) sensations. You just have to hook up a sensitive surface to the intricacies of sensations in such a way that the corresponding percepts reflect fine distinctions in the sensations perceived. In any case, that is the ground of the difference: we can see brains but we can’t see minds. Just think how much simpler your intellectual life would be if you could see both. The “world-knot” might unravel before your eyes, literally.                

 

  [1] I won’t discuss the possibility of having these concepts innately—say, being born with the concept of a bat’s experience (but no bat experiences). This raises other puzzles.

  [2] Of course, I am alluding to Mary in her black and white room.

  [3] For one thing, seeing sensations would allow us to draw pictures of them, as we can draw pictures of C-fibers. We could then set the pictures side by side and compare them. As it is, we can draw no picture of pain to compare with our picture of C-fibers. What would that do to the mind-body problem?

                                                           

 

 

 

Real Freedom

 

 

The free will debate is usually characterized as a dispute about whether or not freedom is compatible with determinism. Determinism is understood as the doctrine that all events are subject to the laws of nature, which admit of no exceptions. So an act like raising your arm falls under natural laws, which guarantee that in the same antecedent conditions the same action will be performed. The question then is whether freedom is consistent with the uniformity of nature: does determinism in the defined sense rule out free will or is it compatible with free will (and perhaps conducive to it)? The first point I want to make is that this is not quite the right way to put the issue: the question isn’t about whether freedom is compatible with determinism in the sense defined—that is just one form of the question. The general question, of which this is a special case, can be put in a variety of ways and it useful to have a sense of these ways: Is freedom compatible with determination, causation, psychological and physical laws, constraint, necessity, dependence, fixation, supervenience, grounding, predictability, forcing, compelling, being subject to, being based on, being conditioned by, being controlled by, being in the grip of, being the result of? That is, if an action A is in accordance with a desire D, can A be free if it bears any of these relations to D? Put most generally, is freedom of action compatible with dependence of some kind? The compatibilist says yes while the incompatibilist says no. The strong compatibilist (as I define him) holds that freedom requires such dependence, as well as being consistent with it; but the further spelling out of the nature of the dependence is not yet stated. So far it is an abstract placeholder.

This leaves room for a formulation not equivalent to the traditional formulation in terms of determinism, namely whether freedom is compatible with causation without laws. Suppose my desire D causes my action A but there is no law subsuming that causal relation, so that D can occur without A and A without D. Then determinism does not apply to A, though there can be a debate about whether the causation involved rules out freedom (or rules it in).  This is because there is still a type of dependence that (allegedly) calls into question the freedom of the action. The claim is that A had to happen given D, and this conflicts with freedom (assuming that freedom requires the ability to have done otherwise). Laws are not the essential consideration here; so denying laws will not save free action from some kinds of incompatibilism. The abstract issue is whether any kind of dependence rules out freedom, where this dependence might not even be causal dependence (as in occasionalism). The question is whether the action follows from the desire in some way (perhaps in conjunction with other psychological states), and laws need not be the only reason for this. Any kind of consequence will generate the problem.

            The strong compatibilist should not then assert that free will implies determinism, as if there can only be free will in a world governed by exceptionless laws; what she should assert is that it is essential to freedom that actions depend on desires in some way, leaving it open what the metaphysics of this dependence might be (suppose she rejects causation and laws on metaphysical grounds). There might be some weird kind of dependence mediated by a capricious God whereby actions are connected to desires; what matters is that the action follows from the desire in some way instead of being quite independent of the desire. We might then say that the dispute concerns the consequences for freedom of desire-dependence, however that is to be understood. The uniformity of nature is a side issue.

            The position I am inclined to accept is that freedom entails desire-dependence (strong compatibilism); and the question this position prompts is whether such dependence is compatible with accepting that agents have an ability to act otherwise than they actually act.  [1] Much ink has cascaded around this question, but I propose to be brief and dogmatic here: “I could have done otherwise” means “I had a choice”. It does not mean any fancy metaphysical business about the course of nature, such as that my actions could flout the laws of nature. It does not mean that two worlds could be exactly alike in their laws of nature and initial conditions and yet agents act differently in those worlds, or that two people could be exactly alike psychologically and yet choose differently. It means simply that I was not constrained by some outside (or inside) force that prevented me from doing what I wanted all things considered. When the gun is to your head you have no choice, as we say, but when you act as you see fit you have a choice—and that is all it means to say that you could have acted otherwise. The phrase carries no metaphysical baggage about the world having alternate futures despite what has obtained so far. And you have a choice even if your actions depend on your desires in some way—indeed that is what choice is. So choice can exist in a world in which actions depend on desires. Choice is compatible with desire-dependence. Intuitively, the ability to act otherwise is a matter of making different choices in the light of different desires, beliefs, perceptions, hunches, personality traits, and so on. It doesn’t require some remarkable capacity to transcend the empirical world and just insert an action into history without any intelligible antecedents.

            I see nothing wrong or misleading about expressing strong compatibilism as the thesis that freedom entails psychological determination (specifically by desires, but not only desires), where this need not imply determinism (though I also believe in determinism about our world). The type of determination in question need not fit any other type of determination in nature, and may indeed be quite mysterious; all that matters is that action not be decoupled from desire (and other psychological states) in the way libertarians sometimes envisage. We are not even required to call the dependence a type of causal relation, still less to assimilate it to other types of causal relation. All we need to say is that the agent acted as he did because of his desires (etc.)—and not because he was compelled so to act by someone with power over him (or anything similar). The essential point is that the strong compatibilist is not committed to holding that actions fall under laws, whether strict or merely statistical; all that is entailed by the concept of a free action is some sort of dependence or determination. This is what the concept of freedom requires, not that actions fall under laws or that they are subject to causality. Equally the incompatibilist does not have to establish the uniformity of nature and the universal reach of causality in order to mount his case against freedom—he just needs a general abstract notion of dependence. The issue between them has thus been improperly formulated and should be recast in the manner suggested here.

            I shall end with a point that I have not seen made: that there is no merit in having a capacity for freedom that involves desire-independence. Suppose it is claimed that two individuals could be exactly alike psychologically (and possible also physically) and yet act differently. That would mean that their different actions correspond to no difference of desire. But what would be the point of being able to act in ways that are independent of desire—what would that get you? Not greater desire satisfaction certainly, nor greater rationality (all the beliefs are the same too). It seems like a gratuitous talent to flout your own psychology, as if you are trying to prove some supernatural gift—“Look, I can act in ways that don’t satisfy my desires or reflect my outlook on the world!” Why would such a capacity exist in us? Do other animals have it, including our closest relatives? What about children? How could it evolve? It seems like a bizarre kind of spontaneity, serving no purpose except to establish a dubious metaphysics. If this is what freedom is, what is the point of being free? No, freedom is the ability to act on your own desires and reasoning, making sure you get what you want when you want it. That is something we can all get behind. You want your choices to be shaped by your desires (including your moral desires) not to be miraculously uncoupled from your desires. It isn’t that things would be better for us—we would be a better class of being–if we were able to act in ways that contravene our carefully considered desires and judgments. That just seems like a pointless eccentricity, nothing to celebrate.

 

Colin McGinn    

  [1] See my papers “Freedom as Determination”, “I’m Free”, and “Freedom Within Necessity”. I defend this kind of compatibilism in these papers and say more what it means to say that someone could have done otherwise.

                                   

 

 

Proprioception and Naïve Realism

 

 

Philosophical discussions of sense perception seldom address proprioception, but it is a question whether theories that hold for the other senses, particularly vision, hold for proprioception. The objects of proprioception are generally taken to be the muscles and joints, possibly also the skin; they do not include all bodily organs. We do not sense our bones in this way or our internal organs (with the exception of the heart and gut, which are muscular).  [1] It might be said that we can perceive our bones (their size and position) indirectly via our perception of the muscles surrounding them, but the skeleton itself contains no proprioceptors. So the bones are not direct objects of internal perception; similarly for the brain, liver, and blood—or the fingernails, hair, and teeth. We know the properties of these things by means of the senses, but we don’t sense them by proprioception; they are not elements in our “proprioceptive field” (compare the visual field). Simplifying, let us restrict proprioception to the muscles: we sense our muscles this way but nothing else—not other people’s bodies or external material objects. The muscles are the proper objects of proprioception; and this is a sense like no other, a sense in its own right. It makes us acquainted with things in a unique way.

            Various questions can be asked about this sense. Is there something distinctive it is like to deploy the proprioceptive sense? Are there proprioceptive qualia? Is it a type of feeling, analogous to touch? Do we sense events in our muscles as well as the muscles themselves (contractions, relaxations)? What properties of our muscles do we sense? Are the muscles perceived to have both primary and secondary qualities? What kinds of perceptual illusions is proprioception subject to? Is it possible to be a skeptic about proprioception? What is the relationship between proprioception and introspection? Do we sense the mind as we sense the body? How is our body image related to our self-image? Does proprioception provide the most basic kind of knowledge of our body? What would happen if we lost all proprioception? Is our conception of our body mainly determined by proprioceptive sensation? To what degree do we model the external world on the body as proprioceptively perceived?

            These are all good questions, but I intend to focus on a different question: Is naïve realism true of proprioception? I hold that the other senses do not satisfy naïve realism in the following sense: their direct objects are not external distal material things but proximate arrays of energy or materiality.  [2] We do not, strictly speaking, see, hear, smell, taste or touch external objects like tables and chairs, or stars and bananas. We see impinging light, hear ambient sounds, smell the chemicals that emanate from objects, taste the chemicals that stimulate our taste buds, and touch the force fields emitted by things (none of these objects is a sense-datum in the traditional sense, not being mental in nature). I will not defend this view here; my concern is to suggest that we dodirectly sense our muscles. Thus there is a fundamental asymmetry between proprioception and the other senses: naïve realism is true of this sense but not the other senses. If I look at my biceps muscle, I directly see the light packet reflected off it and I indirectly see the muscle itself; but when I sense my biceps muscle by proprioception I sense the muscle directly not some sort of energy emanating from it. There is no perceptual intermediary that is the immediate object of my perception. I am acquainted with the muscle itself not merely with the effects it has on my senses. Proprioception is logically unlike hearing (the paradigm sense in my view): we hear the sound an object produces not the object itself (save indirectly), but we don’t feel the “sounds” produced by the muscles—we feel the muscles themselves. When I apprehend my body I really do apprehend my body. There is nothing mediated or remote here, no dependence of one kind of perception on another; I don’t indirectly perceive my muscles in virtue of perceiving something else. In fact, there is nothing else that I perceive when I perceive my muscles—no analogue of light or sound or chemical impingements. It is the muscle itself that falls within my proprioceptive field not some sort of emissary or intermediary of it.

            It is hard to argue for this position except by pointing to the absence of anything that could play the role of intermediary, and also perhaps its phenomenological verisimilitude. What could we proprioceptively perceive butthe muscles of the body? The case is rather like our “perception” of our own mind: we “sense” our thoughts and sensations directly not via some sort of intermediary. Mental states don’t reflect light or emit sounds or send out mental chemicals that enter a mental nose or mouth. Similarly our muscles don’t have these kinds of effects on our internal sense: their properties are immediately given in proprioception. We perceive our muscles somewhat as we perceive light or sound—that is, directly and immediately. But our muscles are solid objects like external objects, so these are the only such objects that we sense directly. I sense your body indirectly via my external senses, but I sense my own body directly (as well as indirectly through my other senses). Proprioception is unique in giving us access to physical objects directly. Thus there is nothing about such objects intrinsically that precludes them from being directly perceived; it is just that objects can reach our minds in different ways, some direct, some indirect. Mostly we sense the physical world indirectly, but in the case of proprioception we are granted a direct route.

            This is not to say that perceptual illusion is impossible in proprioception, or that skepticism doesn’t apply; and indeed both are possible. We have the phantom limb phenomenon as well as the standard brain in a vat scenario. So we don’t know with certainty that we have muscles. The point is rather that the structure of our perceptual relation to the body in proprioception is unlike our other forms of perceptual relation to things: if we perceive our body (pace skepticism), we do so without perceptual mediation—without sensing something else first. It is not that we perceive our muscles by perceiving our skin or something of the sort (as we do when seeing our muscles). In this sense, then, we can be naïve realists about proprioception: we really do directly perceive the physical things called muscles. Of course, we have proprioceptive experiences that are distinct from muscles, but these are not perceptual intermediaries, since we don’t perceive them (we have them). The experiences make it as if we are sensing our muscles directly, and indeed that is true as a point of logical analysis: we literally experience our muscles.

            It is an interesting fact that this asymmetry exists: instead of naïve realism being true or false of perception in general, we have the result that it is mainly false but not universally so. Different philosophical theories of perception apply in different cases. Interesting, too, that our own body should be the object that engages our perceptual apparatus most directly, so that our body becomes the thing most intimately experienced (not counting the mind itself—though the mind isn’t experienced). “Know thyself!” takes on a new meaning. And is it possible that we tend to model external perception on proprioception, regarding it as more intimate than it really is? In fact, there is a sharp logical discontinuity between perception of the body and perception of other physical objects, animate and inanimate. Other bodies resemble our bones in contrast to our muscles.  [3]

 

Colin McGinn

  [1] We can sense pain in internal organs that contain no muscle, and this might be regarded as a form of perception; but that is not the same as proprioception, which has to do with the perception of position, size, and movement. Thus sensory physiologists distinguish proprioceptors from nociceptors.

  [2] See my “Seeing the Light” in Philosophical Provocations (MIT Press, 2017).

  [3] Don’t our bones seem more alien to us than our muscles, as if they aren’t quite ours? Ditto for our internal organs (most of them). We are fonder of our muscles because we know them better. The skeleton is not an object of affection.