 Hi, I'm Peter Adamson and you're listening to the History of Philosophy podcast, brought to you with the support of King's College London and the Leverhulme Trust. Online at www.historyoffilosophy.net. Today's episode, By All Means Necessary, Avicenna on God. There are, we are told, fifty ways to leave your lover, and there are probably at least that many ways of attempting to prove the existence of God. Some are the equivalent of telling your lover you just need a bit of time to yourself, not very persuasive and unlikely to work unless stronger measures are taken further down the line. Others are like moving to a new city without leaving a forwarding address. If this strategy doesn't work, then nothing will, but on the other hand it raises more questions than it answers. In today's episode, we're going to look at a proof like that, the one offered by Avicenna. Along with the famous ontological argument mounted only a few years later by Anselm of Canterbury, Avicenna's proof is probably the most influential and interesting medieval attempt to show that God exists. It was enthusiastically received, repeated, and modified by medieval thinkers writing in Latin, like Thomas Aquinas and Duns Scotus. In the Arabic tradition, meanwhile, it would be known as Burhan As-Siddiqin, the demonstration of the truthful. One sign of its pervasive influence is the widespread later habit of referring to God as wajib al-wujood, the necessary existent, a phrase we find even in the writings of staunch critics of Avicenna. One reason the proof was so popular, I think, is that it rigorously captures an intuition that really does underlie people's belief in God. In this respect, it is unlike Anselm's proof, which tends to strike readers more as a clever trick than as a philosophical articulation of the grounds of faith. Avicenna exploits our intuition that the things around us from giraffes to planets, and indeed the universe as a whole, could quite easily not exist. So the fact that the universe does exist seems to cry out for an explanation. Anticipating Leibniz, whose ideas can in part be traced back to Avicenna, we might say that there should be some sufficient reason why anything at all exists rather than not existing. God would provide that reason. Ultimately, everything other than God would exist because of Him. We might be tempted to press on and ask why God exists. The answer is that the explanatory buck stops with Him. Unlike giraffes and planets, God cannot fail to exist. He is, in other words, a necessary being, and in fact the only necessary being. That's basically the line of thought Avicenna follows, but of course his version is going to be a bit more complicated and tightly argued. First, we need to think back to the distinctions introduced in the previous episode. You'll remember that Avicenna draws a contrast between essence and existence, and explains that something will be impossible, contingent, or necessary depending on how its essence relates to its existence. If something has an essence that precludes its existence, like a round square, then it obviously cannot exist. It is impossible. Contingent things will have essences that are in themselves open, or neutral, with respect to existence. Considered in themselves, they might exist or not exist. To explain why they exist, or don't exist for that matter, some cause needs to intervene, to preponderate them to existence or non-existence, as Avicenna would put it. Finally, a necessary existent would be that whose essence guarantees its existence. Now, what Avicenna wants to do is to prove that there is indeed a necessary existent. This of course would be God. To deny that there is any such thing would mean insisting that everything that exists is contingent, since there are clearly no impossible things that exist. So let's consider that scenario. Could it really be the case that everything that exists, exists contingently? It might seem so. Of course, each contingent thing will need some cause other than itself which will preponderate it to exist. Since that cause will itself be contingent, it will in turn need another cause to make it exist, and so on. An infinite regress seems to be looming here. Where will the sequence of preponderating causes end? But this is actually not the problem raised by Avicenna, and rightly so. To simplify matters, we can see why if we suppose that the sufficient cause of your existence is your mother. She had a cause too, namely your grandmother, who was caused by your great-grandmother, and so on. This sequence may go off into infinity, but so what? Each mother has a mother, so nothing is uncaused. The only problem would be if the causal sequence cannot be infinite for some reason, for instance because the universe has not existed eternally. But Avicenna is not the man to say that, because as we'll see, he thinks the universe is indeed eternal. Instead, Avicenna asks us to think about the entire collection, or aggregate, of all contingent things. In other words, we should consider the sum total of every contingent thing that exists now, has ever existed, or ever will. Now, what is the status of this collection of things? Obviously it isn't impossible, because it does exist. Rather, the collection as a whole is presumably contingent. This is the point where Avicenna is articulating the basic intuition that the whole universe, with its entire history, could have failed to exist. But if the whole aggregate is itself contingent, then it must obey the rules that apply to any contingent thing. In other words, it must have an external cause that preponderates it to exist. Now Avicenna pounces. The external cause is certainly not impossible, since it would never exist in order to serve as a cause. Nor can it be contingent, since then it would be included within the big aggregate of all contingent things that it causes. That leaves only one possibility, namely that the external cause is necessary. Thus, we have shown there is a necessary existent, known to its friends as God. It might seem that we could avoid the conclusion by rejecting Avicenna's assumption that the aggregate of contingent things is itself contingent. Okay, each thing inside the collection is contingent, but does that mean that the collection as a whole is contingent? We might consider a mathematical parallel here. Avicenna's aggregate looks a lot like a mathematical set, and sets frequently have features that their members do not. For instance, the set of numbers is not a number. Or if you stopped paying attention in math class when you were 13 years old and don't like that example, think of a clock. The parts of the clock might each be small, even though the clock as a whole is big. In general then, wholes don't automatically share the features of their parts. So maybe the whole collection of contingent things isn't contingent after all. It might be necessary. Translating that into less technical language, this would mean that the universe, past, present, and future, has no external cause. Instead, it simply must exist, and requests for an explanation of its existence are wrong-headed. That sounds like the sort of thing that a modern day atheist might say, so it's a bit surprising to see that Avicenna is fairly relaxed on the point. He sees that an opponent might raise this objection against his proof, and as if shrugging his shoulders, says that in that case, the opponent would just be giving him what he wants. After all, he is out to prove that there is a necessary existent. The opponent has actually admitted that, it's just that the opponent thinks that this necessary existent is the universe itself. So as Avicenna says, in a way, this is what was sought. The objection is no objection at all, but a capitulation. Unfortunately for Avicenna though, we can now see that his ingenious proof has not gotten him as far as he might have hoped. Perhaps there is a necessary existent, but it turns out to be the universe itself. Or maybe there are even many necessary existents. Perhaps there are many gods, as in pagan belief. Or maybe the necessary things aren't even divine. We might think that numbers necessarily exist, for instance. Or platonic forms. Avicenna may as well go around wearing something that says, I proved there is a necessary existent and all I got was this lousy t-shirt. Unless, that is, he can show us that the necessary existent, established by his argument, is to be identified with the god worshipped in Islam. Avicenna now turns to this further task with great energy, devoting lengthy sections of his various works on metaphysics to showing that a necessary existent must indeed have all the attributes we would associate with God. It turns out, or so he will argue, that necessary existents implies a wide range of other features, such as uniqueness, immateriality, wisdom, power, and generosity. Necessity thus becomes the core idea in Avicenna's understanding of God. In this, he is radically departing from the Aristotelian tradition. Before Avicenna, it was traditional to prove the existence and features of God by reasoning from features of the world we see around us. For instance, Aristotle himself had argued that we need an immaterial divine mover to explain the eternal motion of the heavens. Other arguments invoked the perfect design of the universe to prove that there is a wise and powerful Creator. Avicenna, by contrast, argues that there must be a necessary existent if anything whatsoever is to exist at all. Then, he extracts the entire range of familiar divine attributes from that notion of a necessary cause. That turns out to be a rather laborious enterprise, because Avicenna needs to argue for each individual attribute one at a time. I'll just give you a couple of examples. The first thing he needs to do, of course, is show that there is only one necessary existent since God is unique. Avicenna's argument is ingenious. He asks us to imagine that there are more than one necessary existents, and then he'll show that this would lead to absurd consequences. To keep it simple, let's just suppose that there are two necessary existents, and to make it fun, let's call them Buster and Charlie. Now, obviously, neither of them can be in any way a cause for the other. If Buster were a cause for Charlie, then Charlie would be causally dependent on Buster. But being causally dependent means being contingent, and we are supposing that Charlie is necessary. Obviously, the same goes for the reverse. Buster cannot be dependent on Charlie either. So for both to be necessary, Buster and Charlie must be entirely causally independent. No problem, that's exactly what we'd expect since both are uncaused necessary existents. But now we can ask, what makes Buster different from Charlie? After all, there are two of them, and there must be some explanation for this difference. Obviously, neither Buster nor Charlie can be the cause of the difference. Then whichever one was responsible for the difference between them would be causally prior to the other. Nor can some third thing explain why they are different. For instance, if Charlie has a mustache and Buster doesn't, then Charlie's mustache is causing Charlie to be different from Buster and causing Buster to be different from Charlie, so the mustache is a cause for both of them, and neither of them are necessary. As Avicenna would put the point, there has to be some distinguishing or individuating feature that prevents our two necessary existents from being identical, and if both are uncaused, then this cannot happen. And if there is no way to explain how multiple necessary existents could be made distinct from one another, we must reject the idea that there are more than one. The necessary existent is unique. Avicenna gives a similar argument to show that the necessary existent must be simple and without parts. His idea here is that if a single necessary existent had parts, then something would need to distinguish those parts from one another, but then by the same reasoning we just used, the parts would wind up being caused to be different from each other and then they would not be necessary. But how can a necessary existent have contingent parts? The necessary existent then is not only unique but simple. Avicenna uses the same word for both features, saying that the necessary existent is wahid, or one. This makes it clear, in case we missed it, that he has just given us a philosophical version of the Muslim doctrine of God's oneness, or tawhid, a typical illustration of how he conceives of philosophy's relationship to the faith of Islam. On this basis, he can quickly take another step towards establishing the divinity of the necessary existent by pointing out that a simple thing must be immaterial, since all material things have parts. So far then, Avicenna claims to have shown that something exists necessarily, and that with necessary existents, just as in the movie Highlander, there can be only one. This means that the necessary existent will be unique, simple, and immaterial. It is starting to sound more and more like God, and the next step will get us closer still. Avicenna continues to pursue the line of thought we've just been following, by emphasizing that the necessary existent can have no connection to matter whatsoever. After all, matter in the Aristotelian framework is one of the four kinds of cause, and a necessary existent can have no cause. What would such an immaterial thing be like? Well, it would have to be an intellect, because, as we'll see in the next episode, Avicenna equates thinking with immaterial activity. Indeed, it must be a perfect, separate intellect, not an intellect like the one you or I have, impaired by being related to a physical body. Now we have reason to affirm such traditional divine attributes as knowing and wise. But is it a move Avicenna is entitled to make? Even if we agree with him that intellects are always immaterial, is it really so obvious that anything immaterial has to be an intellect? Yes, says Avicenna. Thinking is an activity that will belong to any immaterial thing as long as it is not obstructed by being involved with matter. So, that's a sampling of Avicenna's arguments for his claim that a necessary existent would have all the features we associate with God. Of course, each of the arguments needs to be assessed on its own merits. Personally, I find some more convincing than others. For instance, I am not all that impressed by that last move of claiming that anything immaterial is an intellect. Avicenna seems to be simply assuming that intellectual thinking is the only immaterial activity there could possibly be. Notice also that, since Avicenna adopts a piecemeal approach and derives each traditional divine attribute from necessity, one at a time, someone might accept the initial proof for the necessary existent while rejecting his arguments for the various attributes. Such a critic could thereby stop short of accepting the existence of God. Or, the critic might agree that there is such an existent and that it has some of the attributes Avicenna tries to establish, but not all of them. For instance, perhaps it is unique and simple, but not an intellect. Another line of attack might focus on the original proof itself. Here, perhaps the most obvious potential point of weakness is Avicenna's fundamental idea that if something does exist and might not have existed, then it must have some external cause. The atheist objector might say that the universe just happens to exist, with no explanation and no cause, yet without being necessary. This would be an incoherent proposal on Avicenna's understanding of contingency, since for him, something's being contingent just means that the thing needs a cause to preponderate it to exist. The challenge for the atheist, then, would be to propose another conception of contingency, according to which the universe could just happen to exist without being necessary and without having any cause. The universe would be like the sequels to the first Highlander movie, whose existence is inexplicable. Avicenna's philosophical theology certainly was attacked later in the Islamic world, but not really from that direction. His fundamental proof of the necessary existent was popular, if not universally accepted. One critic was of Verroes, who was enough of a dyed-in-the-wool Aristotelian to object to the proof on methodological grounds. He insisted that God's existence has to be shown on the basis of features of the natural world, as Aristotle had done. Thus, for a Verroes, we need to go through physics to prove that God exists. We can't do it with this independent metaphysical argument devised by Avicenna. The more mainstream view, though, was that Avicenna had gone too far by trying to infer all of God's features from his necessity. After all, you can think that God necessarily exists without thinking that everything about God is necessary. But this is precisely what Avicenna thought, which leads him to some rather controversial conclusions. The most obvious problem is that for Avicenna, God must cause the universe to exist. God can have no features or relations that are contingent, so his causing the universe must be something he does necessarily—out with freely-willed gratuitous and generous creation, and in with a necessary emanation of the universe, such as we saw in late antique Neoplatonism. As Avicenna says, God is necessary in himself, but the things that come from him are necessary through another. In other words, their own essences are contingent, so in themselves, they could fail to exist. But once God is in the picture, they absolutely have to exist, because God makes them exist and everything he does, he does necessarily. As we'll see, authors like the theologian and philosopher Alhazali were appalled by this suggestion and chose to fight Avicenna on the ground of the eternity of the universe. Alhazali wanted to insist that the universe is not eternal, and his main reason for this was that he wanted to preserve God's absolute freedom in opposition to the necessitarianism of Avicenna's theory. A further sore point in the later tradition concerns Avicenna's claim that God is an intellect. That itself was not an unpopular claim, at least few Muslims would want to deny that God is wise and knowing. The difficulty was, rather, the manner in which God knows. In one of the most heavily criticized and frequently discussed parts of his treatment of God, Avicenna raises the question of whether, and how, God can know about particular things. There is good reason to think he could not. Suppose that I go to the zoo, admire the giraffes, and then go home and watch a Buster Keaton short film. Ironically, given that that sounds like a perfect way to spend a day, God's very perfection would prevent him from tracking my movements with his knowledge. To do so, he would have to change, first knowing that I am at the zoo, then, a few hours later, knowing that I am chuckling at Keaton's sublime slapstick. But Avicenna must insist that God cannot change. How can he change, if everything about him is necessary? After all, in order to change, it has to be possible for something to be different and then, for that possibility to be realized. But with God there are no unrealized possibilities. There is only necessity. Nor is God's unchanging nature the only problem here. Avicenna adheres to the long-established principle which we first saw with Aristotle and have revisited more recently in the interview about Al-Farabi with Deborah Black, that the best kind of knowledge is universal and necessary in nature. We can apply this kind of high-grade knowledge or understanding to the world around us because we become aware of particular things that fall under universal concepts. For instance, I might universally know that giraffes are ruminant animals. So when I come across Hiawatha, who is a particular giraffe, then I can deploy this understanding and conclude that Hiawatha is a ruminant. But God, being a perfect separate intellect, should have only the most perfect kind of cognition, namely knowledge that is universal and necessary. Of course, that fits in perfectly with Avicenna's general claim that everything about him is necessary. So this is one bullet Avicenna is willing to bite. He says that God does know particulars but in a universal way. He gives the example of a particular eclipse which God could know about by timelessly knowing the necessary laws of celestial motion. As the creator of all things, God has a universal knowledge which covers all of what He has created. Again, this would provoke massive criticism among later authors. The Qur'an states that not even the weight of an atom in the earth or in heaven is hidden from God. Avicenna quotes this verse from Scripture in his discussion of God's knowledge, proclaiming that He has once again supplied a philosophical elucidation of Islamic belief. But for many readers this was a bluff. For them, a necessary existent that knows things only universally and not one at a time could not be equated with the personal untrammeled God of the Revelation, the God who is, as the Qur'an states, closer to man than His jugular vein. We'll see a range of criticisms in this vein before long when we get to Al-Ghazali and other opponents of Avicenna's necessitarian presentation of God. But we're not done with Avicenna yet. Next time we'll be looking at what is, along with the proof of the necessary existent, his most famous argument. This is the flying man thought experiment. It asks us to imagine someone being created by God in mid-air, without any access to the sensory world around him, and to consider what such a person would know about himself. As much as I hate to leave you hanging, though, for the month of August I'll be on my usual summer break. I'll be writing some more podcast scripts and quite possibly spending some time in a Bavarian beer garden or two. If only that were not merely possible, but also necessary. So please join me again in September, when I'll be putting out onto the airwaves a newly created episode on Avicenna's views about the soul and self-awareness, here on The History of Philosophy Without Any Gaps.