Avicenna, the Floating Man
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Avicenna, The Floating Man Avicenna begins by noting that living things DO things. For instance, they perceive by the senses, are moved by volition, take in nutrients, grow, and reproduce. Material bodies act in these ways. But, what is it that causes physical bodies to do so? He calls the source these actions (“the principle of these actions”) the soul. Avicenna thinks that there must be ONE source of these actions, because the mental faculties all interact with one another (for instance, the perceptual faculty of sight might interact with the emotional faculty of sadness, and so on). In that case, there just HAS to be some central hub, or “nexus” for all of the mental faculties. He writes, “these faculties must have a nexus that joins them all together and to which they are bound as a group” So, we know that a mover exists, “something that uses the body”; and this mover (or, nexus of all of your physical and mental activity) is “the thing that each of us sees as himself”. The mover is YOU, the living, thinking individual. But, what ARE you? 1. Proof of the Immaterial Soul: Avicenna argues that the “self” is immaterial. Cannot Be a Body: Imagine that your “self” IS a body. Well then, in that case, it would have to be (a) your WHOLE body, or (b) some PART of your body. Consider (a): You are your WHOLE body That’s clearly false. Surely you can lose a PART of your body and still continue to exist, right? None of your fingernails are a foot long and your hair is not down to your feet. So, I presume that you were not afraid to cut them for fear of going out of existence. It is clear that we can even lose more significant things like an arm, or a kidney, and still continue to exist. Avicenna writes, “If it [the self] is the whole body, then if it lost some part of itself, what we perceive to be us would not exist. It is not like that, however.” (al-Shifa) Consider (b): You are a PART of your body Imagine, for instance, that your “self” is just your heart, or your brain. But, surely you were aware of the existence of your self long before you were aware of the existence of your heart or brain. He writes, “If … a heart, a brain, or some other organ … is identical to … the thing that I perceive to be myself, then my perception that I am must be my perception of that thing.” (al-Shifa) But, “one can know that his self … existed without knowing that he has a heart …” (Epistle on the Ma’ad) 1 In short, if X and Y are numerically identical, then to perceive X is also to perceive Y. It follows that, if the self is numerically identical to the brain, then to perceive the self is to perceive the brain. However, it is not like this, Avicenna says. For we DO perceive the self WITHOUT perceiving the brain (or the heart, etc.). In short: The existence of my SELF is known immediately. However, “the existence of such organs [e.g., heart, brain, etc.] is not revealed to you except through dissection.” (Remarks and Admonitions) The Floating Man: Avicenna supports this line of reasoning by way of a thought experiment, known as “The Flying Man” or “The Floating Man”. The Floating Man Imagine that a fully grown man pops into existence, floating in a sort of void. The air is neither hot nor cold, and there is no wind blowing, so he does not feel it. There are no sounds, no smells. His eyes are closed. Nothing is touching him. His limbs are spread away from his body, so he is not even touching himself. In effect, he is in something like a sensory deprivation tank. What would this man believe? What could he come to know? Answer: Avicenna says that he would know one thing for certain; namely, that he exists: “He has no doubts about asserting his self as something that exists …” (al-Shifa) At the same time, there is also something important which the Floating Man does NOT know for certain; namely, that he has a body. For, he affirms his own existence “without also [having to] assert the existence of any of his exterior or interior parts, his heart, his brain, or anything external.” (ibid.) Why not? In short, because the concept of existing and the concept of having a body are distinct. The Floating Man can coherently imagine one without the other. Knowledge of his own existence does not logically entail knowledge that he has a body. Conceptually, having a body is not a necessary condition for existing. He writes, “if it were even possible for him in such a state to imagine a hand or some other extremity, he would not imagine it as a part of his self or as a necessary condition of his self.” (ibid.) However, if one’s self and one’s body are conceptually distinct, then they must ACTUALLY be distinct. For, “what can be asserted as existing is not the same as what cannot be so asserted and that what is stipulated is not the same as what is not stipulated.” (ibid.) Since the Floating Man can be confident in affirming the existence of his self, but is NOT confident in affirming the existence of his body, then they must not be the same thing—otherwise, if they WERE one and the same thing, then the affirmation of one would just be the affirmation of the other. 2 [Consider: Richmond is the capitol of Virginia. The terms ‘Richmond’ and ‘the capitol of Virginia’ refer to one and the same thing. So, if I affirm something of one, then I automatically affirm it of the other; e.g., if I affirm that the population of Richmond is 1.2 million, then I also affirm that the population of the capitol of Virginia is 1.2 million. On the other hand, if I affirmed something DIFFERENT about them, then I could deduce that the two were NOT one and the same thing. For instance, if I knew that Richmond was in North Carolina, but the capitol of Virginia is in Virginia, then I would be able to infer that they were not one and the same thing.] Avicenna concludes that the “self” is distinct from the body. He says, “what [the reader] has been alerted to is a way to be made alert to the existence of the soul as something that is not the body—nor in fact any body …” (ibid.) His argument seems to be as follows: 1. The Floating Man is certain that he (i.e., his self) exists. 2. The Floating Man is not certain that any body exists. 3. But what is known for certain must be different from what is not known for certain (i.e., if one is certain that X exists, but is not certain that Y exists, then X is numerically distinct from Y). 4. Therefore, the Floating Man is distinct from (i.e., is not identical to) any body. [Objection: But, is premise 3 true? Consider someone who knows what water is, but has never heard of H2O. Though it is true that Water= H2O, can’t this person know that water exists WITHOUT knowing that H2O exists? If premise 3 is true, then either this difference in knowledge is impossible, or else waterH2O. But, both of those options are absurd. To illustrate, consider the following “argument” which parodies the above: 1. Sophia is certain that Mark Twain exists. 2. Sophia is not certain that Samuel Clemens exists. 3. But what is known for certain must be different from what is not known for certain (i.e., if one is certain that X exists, but is not certain that Y exists, then X is numerically distinct from Y). 4. Therefore, Mark Twain is distinct from (i.e., is not identical to) Samuel Clemens. Clearly, the argument is unsound, for Mark Twain IS (i.e., is identical to) Samuel Clemens. But, maybe Avicenna has put his finger on something weird. If there is an ‘=’ sign between two things, we SHOULD be able to substitute them out in various sentences. For instance, 2+2 = 4 ; but ‘4 = 3+1’ is also true, so we should be able to sub in ‘3+1’ for ‘4’ and still get a true sentence, like this: 2+2 = 3+1 3 Fred is a bachelor ; but ‘bachelor’ = ‘unmarried male’, so the following substitution also delivers a true sentence: Fred is an unmarried male. So why doesn’t this substitution work? Sophia knows that Mark Twain exists ; but Mark Twain = Samuel Clemens. Therefore: Sophia knows that Samuel Clemens exists.] 2. Further Proof That the Soul is Not Corporeal: A second (more complicated) proof. Consider: If the soul were a corporeal body, then it would have to be one that is either (1) indivisible, or (2) divisible. (1) Indivisible Bodies are Impossible: But the idea of (1), an indivisible corporeal thing, is absurd. To put it simply, a bodily thing always has extension (i.e., it is spread out in space). But, what has extension has a left half and a right half—i.e., two PARTS. But, whatever has parts is (by Acivenna’s definition) NOT indivisible. Perhaps you’re not convinced. You might say, “Yeah, but material objects have planes, which are made of lines, which are made up of non-extended mathematical points—and those are indivisible.