Aristotle's Epistemology (History of Philosophy)

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.historyofphilosophy.net. Today's episode, A Principled Stand, Aristotle's Epistemology. All men, by nature, desire to know. This is the opening line of Aristotle's metaphysics. It expresses his conviction that the thirst for knowledge is not something limited to full-time thinkers like himself. It's something we all share. But the fact that everybody wants something doesn't mean that everybody gets it. After all, most of us would like to live forever, but no one has managed that yet. I myself hope to achieve immortality. I may need to, if I'm going to cover the whole history of philosophy in these podcasts. Surely, in the case of knowledge, though, everyone does get what they want, at least to some extent. Everybody knows quite a few things. You, for instance, know that you are listening to a podcast right now. You know that the podcast is about Aristotle. You know what you had for breakfast. And I do hope you had a good breakfast, since, as you also know, it's the most important meal of the day. But what allows you to say that you know any of these things? What, in fact, is knowledge? As I've mentioned before, this is the core question of the area of philosophy called epistemology, the study of knowledge. Epistemology recognizes a basic distinction between knowledge and mere belief. Clearly, these are different. If I know something, then it seems I must also believe it. To know you're listening to a podcast, you must at least believe you're listening to a podcast. But the reverse is not true. I optimistically believe that Arsenal will win the English Football League next year, but sadly, I do not know this. But if we can believe things without knowing them, then what's the difference? Well, it can't just be that knowledge involves truth, whereas belief doesn't. Admittedly, there are false beliefs, but there are also true beliefs, which don't count as knowledge. If Arsenal does turn out to win the league, that won't mean that my belief was in fact knowledge. It was more like a lucky guess or wishful thinking, or perhaps even a well-informed prediction, but not knowledge. As we've seen, Plato was the first philosopher to distinguish clearly between knowledge and true belief. He does so in the Mino, the Theaetetus, and other dialogues, and his characters have little trouble showing that there is indeed a distinction to be made here. But it is more difficult to say what turns a belief into knowledge. The Mino suggests that some kind of causal account might do the trick, but fails to provide details. Some interpreters think that Plato gave up on the project in the Republic, that in this dialogue, knowledge is seen not as true belief plus something, but instead as the grasp of a completely separate kind of object, namely, the forms. In episode 26, I suggested some reasons to doubt this interpretation, but on any interpretation of the Republic, it looks as though knowledge, and in particular, knowledge of really important things like justice, the good, and so on, is reserved for a small elite. The rest of us make do with belief, while the philosophers use dialectic to achieve true knowledge. On this issue, as on many others, Aristotle has paid close attention to Plato. In his treatment of knowledge, he reacts to Plato, and finds quite a lot to agree with, even if he also openly disagrees with his master on occasion. Aristotle not only accepts the fundamental distinction between knowledge and belief, he also, like Plato, sees knowledge as a formidable accomplishment, one achieved by the elite, and only with great difficulty. We learn this from a work with the rather unenticing title Posterior Analytics. You may remember from last time that Aristotle's groundbreaking work in logic is presented in a treatise called the Prior Analytics. What it is prior to is the Posterior Analytics. Both works are complicated and undertake a variety of projects, but if you wanted a one-sentence summary of both analytics, you could do worse than to say the following. First, in the Prior Analytics, Aristotle explains the rules governing valid arguments. Then, in the Posterior Analytics, he explains which valid arguments are sufficient to provide knowledge. Okay, that was two sentences. So, the Posterior Analytics is, among other things, the closest thing to an Aristotelian treatise on epistemology. It asks, what are the conditions that have to be satisfied if we are to take ourselves as knowing something? The short version of Aristotle's answer is that you know something when you have demonstrated it. This immediately helps us to see what the Posterior Analytics has to do with the Prior Analytics. Demonstrations are valid arguments, so we need to know the rules of argument before we can say what a demonstration is. In fact, a good way to think about demonstrations, as Aristotle conceives them, is that they are the best kind of valid arguments. But this brings us to the long version of Aristotle's answer. Not just any old valid argument will be demonstrative and thus provide knowledge. Aristotle thinks that there is a whole series of criteria that need to be satisfied to achieve demonstration, like a series of boxes that need to be ticked. Looking at these criteria will take us through the rest of this episode and expose just how demanding Aristotle's epistemology turns out to be. Let's first remind ourselves of what a valid argument looks like according to Aristotle. It's going to be an argument with two premises which have a term in common. These premises will, together, yield a conclusion. Such an argument is called a syllogism, and Aristotle thinks that all productive arguments can be reduced to certain types of syllogism. So demonstrations will definitely be syllogisms, but which ones? Aristotle's fundamental idea here is that if you are going to demonstrate something, then you need to explain it. So the syllogisms that are demonstrative will be the ones that are explanatory. For instance, I might notice that giraffes have long necks. As a giraffologist, I now ask myself, gosh, why do giraffes have long necks? What I'm looking for is an argument that will explain this feature of the noble animal that is the giraffe. Now, I know what you're thinking. If I've noticed that giraffes have long necks, I already know it, I don't need to demonstrate it. What Aristotle is after is some kind of systematic, well-founded, we might even say scientific, understanding of things like the fact that giraffes have long necks. Indeed, it's been proposed that understanding would be a better translation of the Greek episteme than knowledge, at least in this context. This leads us then to the first important box that needs to be ticked. A demonstrative syllogism needs to be not only a valid argument, but also genuinely explanatory. It has to show me not just that the conclusion is the case, but why the conclusion is the case. In our example, an appropriate syllogism might be something like this. Giraffes are land animals that eat leaves off tall trees. Land animals that eat leaves off tall trees have long necks. Therefore, giraffes have long necks. Aristotle will point to the feature that links the two premises, he calls this the middle term, and say that in a demonstration, the middle term helps to explain the conclusion. Giraffes have long necks because they are land animals that eat leaves off tall trees. So, are we done? Will any valid argument that explains something in this way count as a demonstration? Well, no. Aristotle adds several more criteria, and the next one I want to mention is a bit more surprising. His idea is that if we are really going to have understanding, what we are after is not an explanation of just one particular thing, but of a whole class of things. Knowledge or understanding must be universal. It will have to do with general features of the world around me. This means that if I'm looking at a particular giraffe, let's say her name is Hiawatha, then it doesn't count as a demonstration if I say that Hiawatha has a long neck because she eats leaves off tall trees. This is true alright, but it isn't an example of episteme, that is, knowledge or understanding. Rather, if I really understand Hiawatha's having a long neck, it's because I realize that she's a giraffe, and understand that her long neck is just one instance of a universal feature that belongs to all giraffes. This connects to something I mentioned last time, the distinction between accidental and essential features. To remind you how this works, the essential features of something are the features the thing has by its very nature. I can't be human without being rational, so rationality is essential to me, whereas my baldness is accidental to me because I don't need to be bald to be human. In fact, I used to be human without being bald, but let's not get any further into that painful subject. So, a giraffe, we're supposing, can't be a giraffe without having a long neck and without eating leaves off tall trees. These features are essential to it. Obviously, the universality criterion is relevant here. The essential features of the thing will be shared with all other members of its kind. If it is essential to Hiawatha that she has a long neck, then all other giraffes must have long necks too. So, here's another box to be ticked. The premises of a demonstrative argument must mention essential features of the things that they are explaining. This is a point worth dwelling on for a moment. Aristotle is claiming that there simply isn't any such thing as knowledge or understanding, in the proper sense, of accidental features, meaning features that are exceptional among a given class. If Hiawatha has a broken toe, for instance, this will not interest the Aristotelian giraffologist, because in general giraffes don't have broken toes. Aristotle accordingly has a strong tendency to relegate accidental or unusual things to his list of things not to worry about very much. Insofar as we're doing science, we aren't going to worry about the accidental features of things. This makes Aristotle very different from modern day scientists. Of course, they do look for regular laws or patterns in nature, as Aristotle recommends, but they are also interested in surprising exceptions, in events or features that threaten to falsify their general theories. By contrast, Aristotle encourages us to ignore such exceptions and to study only the generalities of nature. If a giraffe is born without spots or with only three legs, that won't be worthy of study. It will just be ignored as unnatural. Nonetheless, what Aristotle calls knowledge or understanding is closely related to what we call science. Indeed, our word science comes from the Latin scientia, which was used to translate Aristotle's term episteme. Some even say that the posterior analytics is Aristotle's treatise on the philosophy of science. This makes sense, given his criteria for demonstration, which focus on generality and systematicity. I have called it a work on epistemology more generally, but really there's not much difference between Aristotelian epistemology and Aristotelian philosophy of science. He uses the word episteme not just for biology and so on, but also for disciplines like mathematics and metaphysics. For him, all of these are sciences, that is, branches of knowledge. It is in this broader sense that the posterior analytics sets out a scientific program. According to the program, science gets hold of explanations, which are universal and are based on the essential features of things. If Aristotle's criteria are demanding, it is because he is telling us how to achieve full understanding of the world around us, how to become scientists, if you will. But he's still not done. Go back to the fact that you can only know something if it is true. Aristotle draws a rather surprising conclusion from this simple observation. He says that if the things I know cannot be false, then they are necessarily true. When I demonstrate something, not only will I have premises and a conclusion which deal with universal and essential features of things, but I will have premises and conclusions that are always guaranteed to be true. Thus, I can know or understand why giraffes have long necks, because giraffes must necessarily have long necks, a giraffe with a short neck is impossible, and because it's always the case that giraffes have long necks. The first part there stands to reason. If long necks are an essential feature of giraffes, then of course a giraffe can't have a short neck, because if it does, it won't be a giraffe anymore. But we're not likely to agree with the always part, because we don't think that giraffes have always existed. We think they evolved, so that once upon a time, the world had to struggle along without giraffes. Even more depressingly, we anticipate that one day giraffes will probably be extinct. Aristotle will have none of this. For him, all species are eternal. They'd better be, because all knowledge is of eternal truths, so if giraffes didn't always exist, there could be no demonstrative knowledge of them. Couldn't we try saying something slightly different here? We could say, bad news Aristotle, you're wrong about giraffes always existing, but here's something that's always true. If something is a giraffe, then it has a long neck. That could be true even when there are no giraffes. Aristotle might be grateful for the suggestion, but it is not how he thinks about the situation. In his logic, it seems to be assumed that A is B can only be true if there is at least one A. So a statement like giraffes have long necks will for him be false if there are no giraffes. He doesn't explore the strategy I just suggested, which might be more to the taste of a modern logician. You might remember that this issue came up last time, when I said that for Aristotle, either all humans are white or there is at least one non-white human. And I promised to come back to the question of what happens if there are no humans. Well, I've come back to the question. And for Aristotle, the answer is that there are always humans, and if there weren't, if there were no humans, then there would be no true propositions about humans being white or non-white. Let's take stock. We started by saying that Aristotle believes that knowledge or understanding is produced through demonstration, and that demonstration is going to be a kind of valid argument. We've now spent a lot of time looking at the boxes that need to be ticked to turn a valid argument into a demonstrative argument, and we've discovered that to be demonstrative, an argument has to be explanatory, universal, and eternally necessary, dealing with the essential features of the things concerned. Surely, we're finally done, right? Well, yes and no. These do pretty well exhaust the special features of demonstrations, but there is still another worry we might have. Aristotle is keenly aware that my knowledge of a conclusion will only be as good as my knowledge of the premises I use to generate it. For instance, go back to my giraffe example one more time. Suppose I demonstrate that giraffes have long necks on the basis that they eat leaves off tall trees, but I don't understand why they eat leaves off tall trees. Now it looks like I don't understand why they have long necks either. My understanding of the conclusion in the demonstration can only be as good as my understanding of the premises, so those too stand in need of demonstration. Perhaps you can already spot the problem that is looming here. If each demonstration depends on further demonstrations for its premises, then won't I be sucked into a regressive explanation? If I understand giraffes' necks because I understand their eating habits, then I must understand their eating habits on the basis of something else, like maybe the structure of their stomachs. But then there must be something else that makes me understand their stomachs, and so on. There will be no stop to the chain of demonstrations. Aristotle raises this problem explicitly and declares that, like all good things, the demonstrative chain must come to an end. It can't just go on in an endless regress, and neither can it be circular. If I wind up explaining giraffes' necks via their eating habits and their eating habits via their stomachs, I'd better not explain their stomachs on the basis of the kind of necks they have. So the regress must end, but how? Aristotle answers the question at the very end of the posterior analytics. He says that any demonstrative argument will ultimately derive from what he calls a first principle, and that our grasp of first principles must be even more certain and solid than our grasp of the things we demonstrate via those principles. Aristotle is what we nowadays call a foundationalist. He grounds all knowledge on some fundamental, certain truths. These are, of course, not themselves demonstrated, so how do we know them? Aristotle raises but dismisses as absurd the idea that we know these things already, but are unaware of them—obviously an allusion to Plato's theory of recollection. Instead, we get hold of fundamental principles through the most modest of means, using a faculty possessed even by animals—sensation. It is through sensation, says Aristotle, that we arrive at a grasp of the universal features of things, but only after repeated experiences. In a striking analogy, he suggests that this is like a group of soldiers who is in retreat, who turn again to fight so that their formation is restored. Each soldier that turns seems to represent an individual experience, and when everything clicks as it were—their phalanx snapping back into line, the shields in a neat row again—that is like getting the universal into our minds. Here, Aristotle seems to reveal himself as some kind of empiricist, since he traces our knowledge back to sense experience. He even uses a term which is often translated as induction—the Greek word is epigoge. But Aristotle is no David Hume. His brand of empiricism is not tinged by skepticism. He has a serene confidence that our minds are perfectly fitted to receive universal necessary truths just by examining the world around us. There is a further difference between Aristotle and modern empiricists like Hume. Even though Aristotle appeals to sense experience to stop the regress of demonstration, he isn't relentlessly committed to the idea that all our knowledge somehow depends on sensation. That term I just mentioned, epigoge, also appears in Aristotle to describe the careful consideration of commonly held or reputable opinions. This goes back to something I mentioned in the first episode on Aristotle. His practice as a philosopher is to begin from what already seems plausible, even if these appearances may ultimately be overthrown. Next time, I want to reconsider that feature of Aristotle's philosophy in light of the theory of knowledge I've just discussed in this episode. For some help, I'll be turning to a reputable authority of my own, Hugh Benson, an expert on Socratic, Platonic, and Aristotelian methodology. So don't miss what should be a wonderful demonstration of knowledge, next time on the History of Philosophy Without Any Gaps.