Critique of Pure Reason

"True, the Critique of Pure Reason is not a book for the general public (unless they work very hard at it). But the contribution it makes to philosophy is fascinating, although I don’t think that it’s right in many of its details. It was a powerful effort to make sense of the relationship between thought and the world. In my own more technical work in philosophy I’m fascinated by the same question Kant is asking. It is one of the most fundamental questions in philosophy: how do thought, experience, language and theory-formation relate to the world out there? Critique of Pure Reason is an effort to show that when we try to apply the concepts of our ordinary perceptual experience to what lies beyond sense perception, they run wild, like cogs not engaged with each other. All the concepts we use in thinking about the world, for example unity and causality, are only the properties of our ordinary experience. When we start thinking about things that lie beyond the bounds of our senses, and try to apply these concepts to them, we get into trouble."

"It’s an illuminating way to think of the Critique , as a kind of prolonged wrestling match with Hume. Kant recognizes the challenge Hume poses to human reason, and he tries to show that reason can meet that challenge, that there are proper ways of thinking, correct ways of thinking, there are correct categories of thought, and these have a kind of logical or a priori command over any thought, not just human thought. So instead of human nature, we’re going to get unalterable structures which any reasoning creature would have to be following. For example, in Hume, if, let’s say, human beings came across Martians, there’d be no particular reason to expect the Martians to think in the same way that we do. For Kant, there would. If the Martians think of themselves as individuals inhabiting an extended spatial and temporal world, they’ll have to think like that. They will share a lot of common categories with us: categories like causation, substance, space, time and so on. That’s right, that’s basically the element that Kant wheels out to try to diminish the scepticism about reason that we’ve been talking about, and to put in its place a kind of guarantee: first of all that there will be uniformity in nature and secondly that we’re right to think of nature in terms of causation, space, time and whatever other structures he can dig out. Yes, he says it’s Hume who awoke him from his dogmatic slumbers. He pays the most generous tribute to Hume. He’s also very scathing about Reid and Beattie, who he thinks totally failed to understand Hume. They totally failed to see that Hume is not attacking natural belief. He’s in favour of our natural belief systems, but he’s attacking their foundation in reason. That’s what Kant sets about trying to supply. Get the weekly Five Books newsletter This is very interesting. The key text here is the final section of the Dialogues , section XII. As we’ve been discussing, in most of the Dialogues Hume absolutely destroys the argument from design. But then, in the final section, he turns around, apparently very concessive, and says “Look really the whole issue is just verbal. The theist thinks that the ultimate cause of the universe bears some relation to human intelligence, why should we deny that? Maybe it does. It probably bears some relationship to other processes of nature and human intelligence is just one of those, so let’s not make a meal of this.” This all seems terribly soggy. Just at the point where Philo seems to have won hands down, he turns around and says, “There’s not really much of an issue here.” That of course would anger someone like Richard Dawkins enormously. The greatness of Hume is apparent here. He was a very economical thinker. He doesn’t ever try to prove more than he wants. At this point, what he’s interested in is that there are no implications for practice. He’s reduced what our natural reasoning powers can deliver about God or the ultimate causes of things to the point where we can’t draw any implications for how to behave, who to worship, what kind of doctrines or beliefs to hold. We’re reduced, in effect, to a kind of silence. That is quite congenial to some religious thinkers, but to Hume, it matters enormously, because all the wars and the dogmas and the legal systems which are founded with the alleged authority of religion, in turn, are just creations spun out of our own heads. They’ve got no real foundation in anything else than the cultural habits that their authors bring to the issues. So if you find a religious text telling you that homosexuality is a bad thing, well that text is written by someone and he brought to it his ethics, and he takes out of it his ethics. So, in a nutshell, as I like to put it, Hume’s position is you can’t check out of Hotel Supernatural with any more baggage than you took into it. That’s a very important discovery. It means that arguing about the existence of God becomes kind of pointless. What you should argue about is the implications people think they can draw from it. Yes. I think Hume along with Wittgenstein . My third would be Aristotle , who also deserves lots of credit for his association of the investigation of human nature with the whole investigation of nature. Fourth would be Kant . I think I have to put Kant in over Plato ."

"This is the one book on the list that is a complete no-brainer. If you’re thinking about the five key texts for an understanding of Kant, this has got to be one of them. I began by saying that, in my view, Kant was the greatest philosopher of all time, and I also want to say that this is the greatest philosophical book of all time. This is his masterpiece. It covers a huge amount of territory. Part of what is so impressive is the range of topics that he discusses in the course of it—although, interestingly, it doesn’t cover as much territory as he originally intended. We’ll be looking at other books in due course, and some of the material in those other books was originally going to be part of the Critique of Pure Reason . In a way, what’s going on here is that those other books contain the material that Kant himself thought was most important—the stuff that he was keenest to get to. But before he could get on to those other topics, he felt that he had to do a lot of preliminary groundwork, and that’s what you find in Critique of Pure Reason . But it turns out to be so fascinating, and has such far-reaching implications, that it has become a classic in its own right. Yes. In a way, that’s the point. Some of the questions that Kant is particularly interested in—and that he will get on to in his later works—are questions where this issue is particularly pertinent. So, yes, Kant in this book is interested in limits. He’s interested in the limits to what we can know; he’s interested in the limits to what we can use pure reason to ascertain; he’s interested in the limits to what we can even think about. He’s interested in these limits in various different senses. On the one hand, he’s keen to approach them, to map out the limits from within by doing as much as possibly can be done through the exercise of reason; but he’s also interested in stepping up a level and looking at them from above, asking questions of principle about where these limits are to be drawn and what might lie beyond them. Of course, there’s an inevitable problem that arises there because if you’re asking questions about what lies beyond the limits of knowledge then inevitably the question arises: can you hope to know any answers to such questions? For if you claim you can, aren’t you involved in self-stultification? So, all these tensions are there throughout the Critique , and they’re part of what makes it such a fascinating read. That’s right. What we find in Hume is a classic commitment to empiricism. The phrase ‘empiricist’ is entirely appropriate in connection with Hume. He takes very seriously the idea that our knowledge and understanding of the world are constrained by experience. In some very deep sense, they are limited to what we can experience. The reason why Kant says that he was woken from his ‘dogmatic slumbers’ when he read Hume was that he had previously, rather unthinkingly, taken for granted that we had the intellectual resources to broach questions and consider issues that transcend experience, in just the sort of way that Hume denied was possible. It wasn’t just that. Hume had also taken his empiricism sufficiently far to call into question some of the basic ways in which we think about experience itself. This also was a bit of an eye-opener for Kant. He recognised that there were issues here that needed to be addressed. He was very impressed by Hume’s arguments, though not actually ultimately persuaded by them, and thought that it was incumbent upon the philosophical community at large, and on him in particular, to do what he possibly could to address these arguments. So that all fed into this broad project that we’ve already described in the Critique of Pure Reason , of trying to determine just how far reason can go, determining to what extent Hume was right in saying that our understanding and knowledge are constrained by experience and to what extent he was wrong. “This is the greatest philosophical book of all time. This is his masterpiece” There’s a lot that Kant is prepared to accept in Hume’s empiricism. He agrees with Hume that there is a fundamental sense in which our knowledge is constrained by experience. Where he most fundamentally takes issue with Hume is that he draws a crucial distinction between—as he puts it—what we can think and what we can know. Kant’s view is that, although Hume is right with respect to what we can know (that that is constrained by what we can experience), we can think about things that transcend our experience. We can have thoughts about things that we can never hope to have any insight into, but where, nevertheless, the very process of thinking about those things can still play a significant role in our lives. So, one striking and obvious example of this, which we will be talking about a little bit later, is the existence of God. Nobody can know that God exists, no one can hope to establish the existence of God, in Kant’s view. This is an issue that lies beyond the reach of our own experience. The various attempts that people have made to prove God’s existence were all, in Kant’s view, futile. He spends a large part of the Critique of Pure Reason laying into these attempts. But it does not follow, in Kant’s view, that the question as to whether God exists should be dismissed as meaningless. It is still a perfectly legitimate and interesting question. There is still room for us to think about God’s existence and perhaps to have faith in God’s existence. Indeed, there is one very striking sentence in the preface to the second edition of the Critique of Pure Reason where Kant describes his project as ‘denying knowledge in order to make room for faith’. So, you can see that there’s a negative project and a positive project that are intertwined. On the one hand, he is curbing our pretensions to know more than we can; but, on the other hand, he is doing so as a means of opening up the ground for the possibility of faith. This is an absolutely crucial distinction that permeates the Critique of Pure Reason and is very relevant to all of the later work as well. Basically, it is a distinction between appearance and reality. Many philosophers have believed that there is a fundamental distinction between appearance and reality. Kant is part of that tradition and makes a distinction between appearance and reality that is as profound as anyone’s. The way this comes about is that, in the process of exploring the scope and limits of our rational knowledge, he comes round to the view that some of what we can know through an exercise of reason can only be explained if it is due to us imposing a framework onto our experiences that is already built into our minds. An analogy that is very often used to illustrate this idea, which is in some ways a crude analogy, but in other ways, I think, a very helpful one, is that of a pair of spectacles. It’s as if we are born with native spectacles through which we see everything but, unlike ordinary spectacles, these condition what we see in a very profound way. Ordinary spectacles can literally colour what you see as well: if you’re wearing rose-tinted spectacles then everything will appear to you as having a rosy hue. For Kant it’s a bit like that, but with bells on. Among other things, he thinks that even the fact that we experience things in space and time is due to these native spectacles that we carry around with us. Space and time themselves are part of the spectacles. “We have knowledge only of ‘phenomena’—Kant’s word for appearances; we don’t have knowledge of ‘noumena’—how things are in themselves” This is why you get this fundamental division between appearance and reality. All that we ordinarily think about, all that we aspire to discover when we’re involved in the natural sciences, is concerned with the world of space and time and that’s the world of appearances: that’s how things look to us through the spectacles. Kant is adamant that we can never take these spectacles off. If we could take them off, then we might be able to see how things are in themselves, but that’s precisely what we can’t do, and that’s why this distinction between appearance and reality hits so hard in the Kantian system. We have knowledge only of phenomena – ‘ phenomena ’ is Kant’s word for appearances – and we don’t have knowledge of noumena – ‘ noumena ’ is the word that he sometimes uses for how things are in themselves. This is related to what we were talking about a little earlier, because the question of whether there is a God or not is not a question about anything that’s going on within the world of space and time. However extensively you search, however closely you peer into the cracks, you are never going to find a divine being: whether there’s a God or not is a matter of how things are in themselves. It’s a matter of the world of reality, not the world of appearances. This helps to tie in with what we were saying earlier about Kant’s conviction that matters like the existence of a divine being are matters of faith, not matters of knowledge. Knowledge is restricted to the world of appearances. We have to think of it as something even more profound than that. No doubt, there are all sorts of interesting ways in which our brains do condition how we experience things: perhaps there are differences between us and other animals so far as that goes, and perhaps there are differences between us and aliens on other planets, if there are such beings. But those are themselves matters of empirical investigation. Our brains are themselves physical objects. That’s all part of what’s going on within this spatio-temporal framework. Kant is talking about something that’s even more profound than that because the very fact that we’re seeing things in spatio-temporal terms at all is part of how we condition our experiences. It’s part of the spectacles that we’re carrying around with us. So, the brain analogy is a good one; but ‘analogy’ is the operative word here. It can at most be seen as another illustration of the idea. That is another important point in this connection. That’s right. Kant believes that these discoveries that he has come to about this fundamental distinction between appearance and reality and all that comes with it are discoveries that are themselves the product of pure rational reflection. Here he is doing philosophy, not science: whatever else it is, the Critique of Pure Reason is a philosophical work. Again, you’re absolutely right: we have to distinguish between what’s going on here and what’s going on when psychologists or physiologists investigate the ways in which brains—or even our minds, for that matter—influence how we see things. Yes. Up to a point, he thinks there’s room for genuine speculation here. He’s absolutely adamant that it’s never anything more than speculation. The minute we think we can derive any conclusion about how things are in themselves, the minute we think we have the intellectual resources to explore beyond the limits of our spatio-temporal experience, we find ourselves in trouble: our arguments start undercutting themselves, and we’ll find we have what look like equally compelling arguments for opposite conclusions. It’s just a mess. We have to admit our limitations and we have to admit that we can’t know how things are in themselves. “The minute we think we have the intellectual resources to explore beyond the limits of our spatio-temporal experience, we find ourselves in trouble” But that doesn’t stop us from speculating, and one possibility that we keep coming back to is that there’s a supremely powerful, benevolent deity directing the workings of the world. Of course, a lot of people have had that belief and it’s played a supremely important role in their lives, and Kant thinks that that’s perfectly legitimate as long as we recognise that it is an article of faith and that it’s not something that we can ever hope to make more secure than an article of faith."

"We all know that he couldn’t write, no matter how much he tried. Even German people prefer to read him in English translations because the translations clarify what he might be saying. I find reading Kant a bit like understanding cricket as a foreigner: hard to get at first, but once you get it, it’s very enjoyable. Once you start to understand the rhythm of that way of thinking, it’s mind-boggling. It’s quite extraordinary. You can feel the power of that way of conceptualising problems. What I have learnt from Kant is an important lesson: when you discuss any philosophical problem there is one fundamental clarification that has to precede any discussion. This is, ‘Does that question make sense to us given the conditions of possibility of the debate?’ When we overstep the limits of what we can process, the information that it is sensible to ask about, then we know that we are stepping into pure metaphysics. For us, today, it is pure speculation when there is no way of being wrong. There’s a lot of philosophy of that sort — especially the philosophy of technology, and some popular philosophy — that’s just pure discourse. Or there is speculation in the manner of a Sudoku game or a chess problem. I have no time for speculating about some possible metaphysical world, while the current one is burning. Kant is a good antidote both to pointless speculation, the anything goes approach, and the purely logical one in which you make some hypothetical assumptions and see what you can deduce. That’s interesting, but it’s no longer philosophy. It’s not talking to its time and to relevant problems that are of genuine concern. It’s intellectual fun, but ultimately pointless. Kant helps us focus on real philosophical problems. Philosophy has a major role to play today. What is happening is that some problems can, in principle, be solved by maths, experiments, and facts, and therefore we don’t call them philosophy any more. Meanwhile, there are more and more philosophical problems arising from new technology and new ways of living. Philosophy deals with the problems that lie between the world of facts and the world of logical possibilities. That’s fundamental. Kant has a lesson that we still have to learn which is that any form of naïve realism — based on the way the world seems to me, or the way science tells me the world is — should not be taken seriously. What Kant tells us is that we process input (the message) from the world (the source of the message) – what we’d now call data. Information is constrained by the data: if you jump out of the third floor window, you’ll break your neck. You don’t build the world from your imagination. Nevertheless, the world isn’t just as it seems to us. The analogy here is, once again, with cooking. The data are the ingredients of our dish. We process them to obtain a specific outcome, which is our information. The relation between the dish and the ingredients is not one of representation, but one of constraining affordances: given those ingredients/data there are only a few ways of cooking/knowing that make sense and transform them into the right dish/information. To put it differently, I find it very naïve when people talk about knowledge as if it were “of” reality: reality is the source of the signals, but our knowledge is of the signals. It’s a bit like saying you hear music on the radio. The music is sent by the radio, but it is not about and does not “represent” the radio. Versions of structural realism in philosophy of science support this view."