 Hi, I'm Peter Adamson and you're listening to the History of Philosophy podcast, brought to you with the support of the LMU in Munich. Online at www.historyoffilosophy.net. Today's episode, Into Thin Air. Avicenna on the Soul. One of the most popular weapons in the arsenal of contemporary philosophy is the thought experiment. It's gotten so you can't venture into any department of philosophy without being asked whether you'd be willing to shove someone off a bridge to block a train before it hits a bus full of school children. Or suppose that your best friend stepped into a Star Trek-style teleportation device, and two identical people popped out at the far end instead of just one. In such a circumstance, would you be willing to buy both of them a birthday present? Thought experiments are nothing new though. Already in antiquity, Aristotle had asked what would happen if there were another universe. He concluded that the Earth in that universe would need to converge on the same natural place as the Earth here, since the two Earths share a nature. Thus the two universes couldn't possibly remain distinct. Which reminds me of my favorite example of a thought experiment from late antiquity. Plotinus wonders whether an eye on the outside of a second universe placed next to ours would be able to see our own universe. He concludes that it would not, since sensation works through a universal sympathy that binds our single universe together. The use of this method in philosophy raises a number of interesting issues, especially when we are considering scenarios like these that are so remote from our experience. Here it may help to draw a distinction between strict impossibility and inconceivability. It is not interesting or helpful to ask what would happen if 2 plus 2 were 5. That's just incoherent and so inconceivable. But it is possible, and philosophically useful, to think about conceivable scenarios like the ones I've mentioned. Such scenarios are almost certainly never going to come about, no matter how long we hang around on railway bridges. Yet they elicit our intuitions about various philosophical issues, from ethics to morality to cosmology. And intuitions are crucial in philosophical reflection, often providing its starting points or objections to what seemed to be a promising theory. So it makes sense that in the Islamic world, the champion of thought experimentation was the champion of philosophy itself, Avicenna. No thinker in any medieval tradition makes more eager or effective use of such scenarios. This probably relates to the ideas about philosophical inquiry I touched on in the episode about his life and works. As we saw there, he believed that intellectual progress is made by finding the linking or middle terms of syllogistic arguments. A thought experiment is not in itself a syllogism, but it can prompt you to reflect more effectively and help trigger an intuitive insight of that elusive middle term. More modestly, the experiment might just guide you towards the right conclusions, for which you could then seek a good demonstrative proof. So Avicenna was a devoted user of thought experiments and other ways of prompting himself and his readers to reach new insights. You'll remember that he wrote a work called Pointers and Reminders. It asks the reader to do most of the work by just hinting and alluding to the arguments that constitute Avicenna's philosophy without actually laying out those arguments. His most famous thought experiment is explicitly labeled as such a pointer or reminder, a tonn bich. It appears in several of his works and is clear that he was very pleased with it. Here's how it goes. Avicenna asks us to imagine someone being created out of thin air, and indeed into thin air, all at once and as a perfectly functioning adult. In one version, he actually tells you to imagine yourself suddenly being created this way, but I'll stick with the third person version. So this man is suspended or flying or falling in mid-air. His vision is somehow veiled, and there is no noise. Also, he isn't touching anything, not even the ground, and his limbs are splayed out so that he is not even in contact with his own body. Thus, he is in a state of total sensory deprivation. Furthermore, he has only just been created, so he has no memory of ever using any of his senses. So now the big question, will this person be aware of anything at all? He won't know that his own body exists, whether his limbs or his internal organs. And yet Avicenna insists he will nonetheless be self-aware. He will have a knowledge, Avicenna says, of his own essence or self. So what does that prove, other than that Avicenna's late-night wine drinking sessions bore some serious fruit? The flying man thought experiment is sometimes compared to Descartes' cogito argument, I think therefore I am, because it appeals to the inevitability of grasping one's own existence. But Avicenna is not trying to defeat radical skepticism, which was the purpose of the cogito. His argument is a different kettle of fish. In fact, he's out to fry more than just one fish. Most obviously, the flying man draws our attention to the phenomenon of self-awareness. Avicenna was fascinated by the fact that we are all always able to become aware of our own existence. The difference between us and the flying man is that our souls are full of the deliverances of sensation, of memories and thoughts. This might fool us into supposing that when we are self-aware, we are aware only that we are having some sensory experience, some memory, some thought. But Avicenna insists that self-awareness is more fundamental than any such mental activity. Indeed, all other mental activity presupposes self-awareness, since whatever I think or experience, I must always be recognizing it as my thought or experience. Of course, we are not always actively aware of this self-awareness, as if we spent all day constantly narrating our own lives to ourselves, like, here I am drinking a coffee, and now here I am drinking another coffee, and now here I am wondering whether I should stop drinking so much coffee. Rather, our primitive self-awareness is a kind of background foundation for all our mental life. Avicenna claims that it goes on even while we are asleep. To become actively conscious of it, we need to focus on it deliberately, and the flying man thought experiment is one way Avicenna helps us to do that. But this isn't all he wants to get out of the argument. He also points out that with the flying man, we have a situation where someone is aware that he exists, but is not aware that his body exists. This Avicenna claims shows that he is not his body, in other words that his self or essence is an incorporeal soul. He's invoking a general rule here, which goes like this. If I'm aware of thing 1 and not aware of thing 2, then thing 1 and thing 2 are not identical. This principle sounds plausible and is confirmed by study of that philosophical classic The Cat in the Hat, where thing 1 and thing 2 are indeed distinct. But is the principle really right? Consider an analogy. Avicenna could have known that he was drinking a glass of water instead of wine for a change. But given that modern chemistry hadn't yet been invented, he could not know that he was drinking H2O. He was aware of the water, but entirely unaware of the existence of hydrogen and oxygen atoms, or the molecules they make up. But that obviously doesn't prove that water is not the same thing as H2O. Likewise, perhaps the flying man is aware of a bodily self without realizing that that self is a body. For this reason, some interpreters have emphasized that Avicenna calls the thought experiment a mere pointer or reminder, a prompt that might help to shake us out of our materialist assumptions. And in fact, if Avicenna really wants to prove that the soul is immaterial, he has other ways of doing it. His favorite argument for this is not the flying man thought experiment, but one that cleverly uses Aristotle's theory of knowledge for metaphysical ends. We've seen numerous times that in the Aristotelian tradition, knowledge in the strict and proper sense should be directed at universals. So if I know about giraffes, I am grasping the universal giraffe rather than a given individual giraffe such as Hiawatha. But what makes Hiawatha an individual giraffe, distinct from all the other giraffes? The traditional answer, which Avicenna accepts, is matter. Because Hiawatha consists of one batch of matter arranged as a giraffe, while her cousin Harold consists of another batch of matter, Hiawatha is distinct from Harold. That suggests that if our minds take on a universal, rather than particular, form, then our minds must be immaterial. Here we might again be tempted to see a bit of Descartes in Avicenna. Though I'm sure Avicenna would have enjoyed being French with all the wine, I think we should again fight off the temptation to see him as a Descartes avant la latre. At least the cliche version of the Cartesian soul, a substance radically separate from the body which can interact with it in only a rather mysterious way, is not what Avicenna has in mind. Rather Avicenna considers only the intellectual part of the soul, what he calls the rational soul, to be separate from body in its activity. In fact, just like giraffes, the human soul needs matter in order to be the specific soul that it is. What makes your soul different from mine is that they are two separate forms given by the active intellect to two different bunches of matter. Whenever a bunch of matter is prepared in the right way, an appropriate form will emanate into it, just as in Al-Farabi's cosmological theory. Before this emanation into some particular matter, the soul doesn't exist. So seriously does Avicenna take this point that he uses it to show the impossibility of reincarnation. If a pre-existing soul turned up to inhabit a new body, then that body would wind up with two souls, the old one that is being reincarnated and the new one that has just been given by the active intellect. This causes Avicenna some problems at the other, more tragic end of the life cycle. Since the only aspect of the soul that operates without bodily organs is the intellect, or rational soul, it is only this rational soul that will survive the death of the body. But once there is no matter to be connected to, how will my immaterial soul be distinguished from yours, or from any other soul? Perhaps the difference is that each soul has a unique range of universal thoughts. You have spent your life studying frogs while I busied myself with giraffes, and this is what will differentiate us after death. Here it's worth noting that in an indirect way, the soul actually needs the body in order to continue its activities after death. After all, how could you know about frogs or I about giraffes if neither of us had ever been in a body? With the exception of a few basic first principles and concepts, Avicenna thinks that everything we know is derived from sense experience. The Neoplatonists had portrayed the body as a hindrance to wisdom and knowledge. Unlike them, Avicenna thinks that we absolutely need the body if we are to activate our intellects and live the life of the mind, whether during our embodied existence or thereafter. Avicenna innovates further when he explores our other psychological abilities. It's obvious that our mental lives do not consist solely of sense experience and intellection. There is also the faculty of memory, for instance, as when you think back to the blessed day when you first came across this podcast. There is also imagination, as when you try to conjure up an image of what your favorite podcaster might look like in person. If that ever happens, prepare to deploy your faculty for disappointment. Drawing on some suggestions in earlier authors, including the renowned Galen and the fairly obscure Nemesius, bonus points if you remember him, Avicenna develops a novel theory of what he calls the inner senses. The basic idea here is that just as we have five outer senses like vision, hearing, and so on, so we have five inner senses. These include memory and imagination, for instance. But Avicenna's most significant proposal here is the inner sense he calls wahm. The word is often translated into English as estimation, because the medieval Latin version of Avicenna's term was estimatio. But this faculty has nothing to do with estimating in the sense, for instance, of guessing how much something might weigh. Rather, wahm's basic function is to graph certain features of the world that are too abstract to be perceived by sensation, but not fully abstract and universal like the things grasped in the intellect. His favorite examples involve animals. When a sheep sees a wolf, it does not just perceive the wolf's great big eyes and frightfully long teeth, but also the wolf's hostility. So the sheep must have something in addition to sensation. It needs a faculty through which it can perceive something like hostility. That's why the sheep runs away, albeit not at a speed that will challenge the wolf much. So prominent are animals in Avicenna's treatment of wahm that I suspect he was driven to hypothesize the faculty largely because he didn't think it was possible to explain the complexity of animal behavior in any other way. Still, this faculty is something that humans too share. Like sheep, even the most woolly-minded of humans, who might never attain to intellection, are still capable of perceiving features of the world that are not objects of sense perception. The hostility of a wolf, for instance, is something immediately noticed even by little girls in fairy tales, so long as the wolf is not cunningly disguised in a grandmother's bonnet. Avicenna uses another word here, which is difficult to translate, when he is talking about such features of the world, manah. In some contexts this could be rendered as meaning, or more broadly something that someone has in mind. For this reason it came into medieval Latin translations as intensio, and you'll usually see it translated into English as intention. But it should be clear by now, Avicenna doesn't really have in mind things you would intend to do. Rather, he is trying to explain how it is that our mental life can be so rich, something difficult to explain with only the resources of the traditional Aristotelian theory that has to get by with nothing but sensation, imagination, and intellect. By adding his new faculty of wahm, Avicenna can more easily explain how both animals and humans experience the world as something more than colors, sounds, smells, and so on. On the other hand, the word wahm also has a more negative connotation. It can refer to a misleading or wrong-headed notion. So Avicenna invokes this same faculty of wahm to explain the spurious impressions we form, including those that we can hardly resist even when we know that they are wrong, as in cases of visual illusion. I'd like to pause to dwell on the importance of non-human animals in the story Avicenna is telling here. I just suggested that were it not for the relatively sophisticated behavior of sheep and other animals, Avicenna might not have felt the need to posit the faculty of wahm. But once he did, he inferred that it should belong to humans too, and found other functions for it to carry out. Though it may not be obvious, we're seeing here how the history of medicine has an impact on philosophy. Galen, as you might remember, had proved that the soul's ruling faculty is seated in the brain. He proved that by doing dissections of animals, not people. The implications for human psychology were obvious, without Galen needing to cut open human beings. Avicenna's writing on medicine is deeply influenced by Galen and it's no coincidence that his theory of the internal senses makes an appearance in that context too. Inspired by Galen, he assigns his five inner senses to different parts of the brain. One of many subplots in the history of philosophy and science is the long-running debate about how much we have in common with animals. Perhaps the greatest push in the direction of seeing animals as somehow kindred to us has come from anatomical research and the psychological theories based on that research. But of course Avicenna thinks that we are capable of something that no non-human animal can do. We can think. This is thanks to our intellects, which as we saw have the job of grasping universals. If we are like animals and having outer and inner senses, we are like God in that we have this ability to engage in intellection. Also because we are able to grasp ourselves using our intellects just like God grasps himself. In a point closely related to the conclusions of the flying man argument, Avicenna points out that whenever we know something, we can also know that we know that thing. All knowledge, in other words, is at least potentially accompanied by self-knowledge. God's case is not so different. He is better than us mostly in that his self-knowledge is of a better object, namely himself, and that it never ceases. But his knowledge does have an intellectual nature, which is why, as we saw in the last episode, Avicenna thinks that God can only know particular things through a grasp of universal truths. Given that we are not God and don't have an internal and perfect grasp of everything we can possibly know, how is it that we go from not knowing things to knowing them? This is one of the most hotly debated areas in research on Avicenna because he seems to give two answers. The first is an answer we might call empiricist. He thinks that after encountering sensible things, we are able to arrive at universal knowledge through a process of abstraction. This process was a matter of great interest to Avicenna, who discussed in detail how we can use induction to generalize from our experiences to understand universal truths about the world. For instance, after seeing a number of giraffes, we might be able to make the universal judgment that all giraffes are tall. And that seems like a pretty good answer to the question of how we acquire knowledge. Why then, does Avicenna also give a second answer, which is apt to strike us as considerably less good? Usually that we receive forms and emanation from the separate agent intellect, the lowest of the intellects of the celestial spheres. Usually philosophers have a hard time explaining how knowledge comes about. Avicenna though is so good at this philosophy business that he's come up with two explanations. How could both be true though? If we abstract universal forms from sense experience, why do we need the agent intellect? And if we have an emanation from the agent intellect, why do we need to go through the laborious process of abstracting from sense experience? Probably the answer is that the two accounts are aimed at explaining different things. The bottom-up process of abstraction explains why we do need sense experience to arrive at knowledge. You will never get to know about giraffes if you have never had experience of a giraffe. The top-down story about emanation, meanwhile, helps to build a strong link between Avicenna's theory of knowledge and his cosmology. However as in Al-Farabi, Avicenna's agent intellect is the so-called giver of forms, the source of forms that are emanated into matter, for instance when plants, animals, and humans are generated. If the agent intellect is the origin of forms in such material things, and also an origin of the forms in our souls, that would guarantee that the forms in our mind are a perfect match for the forms in things in the outside world. Another advantage of the agent intellect is that the forms we come to understand will have somewhere to reside when we are not thinking about them. Suppose I come to understand all about giraffes, then take a break to think about sheep for a few months, but then I revisit my knowledge about giraffes. Where has the universal form of giraffe actually been existing this whole time? Not in my soul since I was thinking about something else, and not out in the physical world since there is no universal form of giraffe out there, only particular giraffes like Hiawatha. The agent intellect is a kind of permanent home or storehouse for these forms, guaranteeing that they are always available, ready to be downloaded, if you will, by those who have managed to get access to them. Here Avicenna is adopting and transforming the theory of knowledge we found in Al-Farabi. It's yet another example of how he innovates within the framework provided by the Aristotelian tradition, which provides me with an excellent transition to the next episode, in which we'll be hearing from the author of the classic study Avicenna and the Aristotelian Tradition. So come to your inner-senses and remember to join me for an interview with Dimitri Gutas, which will be ready to be downloaded next week, here on The History of Philosophy, without any gaps. Thank you.