An Enquiry Concerning Human Understanding

"This was written about a decade after the Treatise , and it was designed to make the doctrines of the Treatise — or at least the ones that by that time Hume found himself wedded to — more accessible. These are the doctrines of the first book of the Treatise , which is the book that concerns itself with metaphysics, epistemology and the nature of human understanding. The Treatise , in Hume’s famous phrase “fell dead born from the Press,” in other words it didn’t get the audience he had hoped for. So he recast important doctrines in the Enquiry . There’s some cost: some of the really difficult and intriguing doctrines of the Treatise get lost or very much suppressed, but at the same time it is a much more accessible and readable book. No, I think among great philosophers it’s almost unique. I can’t think of another case. Perhaps you could see Berkeley’s Three Dialogues as a kind of recasting of his Principles , that’s the nearest case I can think of. He felt he had something important to say, particularly as regards skepticism about religion. He was anxious to get it out, to enable people to appreciate both the scope and the limits of human reason — and therefore to avoid dogmatism. In that respect he was a follower of John Locke, and arguably Berkeley himself. The 17th and 18th centuries were preoccupied with the idea that if we had a proper understanding of human nature, we’d have a proper account of human understanding and of its limits. That was very important to him, and to Locke for that matter. That’s right. The doctrine that eventually emerges is called “mitigated skepticism” by Hume. He never had any time for exaggerated skepticism — the kind that led Descartes to worry about whether he might be dreaming all the time. But Hume did think that overconfidence and dogmatism led to intolerance, to faction, to a lot of the crimes of human history. So if you could show, in a decisive way, where our limits lie, we could improve on that abysmal history. Yes this was perhaps Hume’s first great — it’s always dangerous in philosophy to say — discovery. I think other people had been aware of problems of induction before Hume, but there’s no doubt he put the matter in the classic way. What he finds is that the confidence we have in natural law — in the regularities and uniformity of nature, in the future being about to resemble the past — has a source in our animal nature. Animals too expect things to go on much as they have gone on — but it has no justification in reason. There is no a priori way of showing that it’s even probable that the future will resemble the past. Absolutely. There’s nothing available to our understanding to show us why things must keep on as they apparently always have. Very much so. This is one of the perpetual drumbeats in Hume. The message that he is constantly reinforcing is that we have to work with human nature, as we’ve got it. There’s no point in trying to kick it over. Exaggerated scepticism tries to kick it over and that’s just not going to work. It’s not going to be a possible way of living for human beings. So we have to follow nature, but at the same time, we shouldn’t think we thereby get more insight, more justification in reason, than is afforded by the proposition that, “That’s the way we are, that’s how we think about things.” That’s exactly it. This becomes rather difficult. The famous section X of the First Enquiry on miracles is this wonderful epistemological argument that it can never be reasonable to believe in a report of a miracle, because the probability that human testimony is letting us down is always greater than the probability of a miracle having occurred. So if someone comes to you with a report of a putative miracle — flying pigs were seen in Cambridge today — the right response is always going to be to worry about how on earth this report got going, not whether there were flying pigs in Cambridge. Because, in effect, the miracle monger, the person who is giving you a report of a miracle, faces a bind. They’ve got to take on something which is antecedently as improbable as it could possibly be, otherwise they would just say it was a rare event. So if I tell you that three horses ran neck-to-neck in the Grand National, well that’s not very common or possibly very likely. But if I tell you that one of them then beat the other by flying through the air, that’s not just unlikely, it’s a miracle — it’s clean contrary to everything we believe about nature. Yes, so there’s a certain amount of muddiness about the overall picture that Hume is offering. It does seem as though the argument against miracles requires some confidence in probabilities, and then of course you might ask, “Where does that confidence come from if reason is silent? Surely it’s silent about probabilities as well?” So there is a difficulty adjusting the chapter on miracles to the overall philosophy of induction and science."

"David Hume was a really remarkable thinker and writer of the 18th century. He was an atheist, or at least a very skeptical agnostic in a religious age, which made it difficult for him to find a job as a philosopher. He was an independent writer for most of his life, and a very successful one. As a young man, in his early 20s, he published a brilliant book known as A Treatise of Human Nature , but it was quite densely written and he famously described it as falling “dead-born from the press”. It wasn’t taken up, it wasn’t discussed. He actually wrote a review of it himself, to summarize it, hoping that would help. So, amazingly—something that you wouldn’t catch many people doing today—he rewrote the book in a more popular way, expanding it in some ways, omitting other bits, because he felt that part of the problem was the style of his communication. He’s a brilliant writer, very witty, sometimes ironic, so he rewrote the Treatise as the Enquiry Concerning Human Understanding . This was picked up and became very popular as a book. He also wrote many essays specifically for a popular audience and also a long history of England that was also very popular. “Like John Locke, he thinks that the mind is a blank slate, filled by experience” In the Enquiry he puts forward his particular empirical account of the mind. There’s a whole section on morality and so on, but the key bit for me is where he’s talking about how, following on from John Locke and the tradition of seeing the mind as a blank slate, we get ideas from what he calls ‘sense impressions’. If you think of an impression as like a footprint left in the sand, the senses get impressed, somewhat passively, by information that comes in from outside. And the impression that’s left in the mind, when we think about it away from what we’re seeing, is called an idea. The whole opening part of the book is about where we get our ideas from, and is it possible to have an idea without a corresponding impression? Can you think about things that you’ve never actually experienced? And he suggests not. You can combine ideas, but everything that is within the mind has come from some prior impression. That’s extremely controversial, because people think of genetics, of patterns of thought that must be there in the mind. Kant reacted very strongly to this, he described Hume as ‘waking him from his dogmatic slumbers.’ And Kant’s Critique of Pure Reason is an attempt to show that certain sorts of patterns must be imposed on all our thought, in order for us to have any thought at all. But Hume’s empiricism is very interesting and very, very important. He’s called an empiricist because, like John Locke, he thinks that the mind is a blank slate, filled by experience. Empirical knowledge is a knowledge acquired through the senses as opposed to by some kind of a priori reasoning. I know that apples are red and crisp because I’ve seen red apples and bitten into some of them. These are empirical observations that I’ve made from which I generalize. Many people think that two plus two equals four is not an empirical observation, it’s not because I’ve added two apples and two oranges and got four fruit over and over again that this is true—it’s because of some kind of abstract relationship between symbols that I can recognize as holding. Hume would agree and see this as a relation between ideas. Somebody might say we need to get the empirical evidence for those symbols – John Stuart Mill, a later empiricist philosopher, bit the bullet and claimed that mathematics too was indeed based on empirical generalisations. Also within this book—which is three books joined together—there are some controversial and fascinating essays on religion, most notably one on what we call the ‘argument from design’. This is the argument that there is an analogy between natural objects, like the human eye, or the human heart, and designed objects, like the workings of a clock or a carriage or a building. If you look at the human eye, how could it not have been designed? Surely something incredibly powerful and benevolent must have created it? Hume takes that apart as an argument from analogy and looks at its weaknesses. He did this more thoroughly in a brilliant posthumous book Dialogues Concerning Natural Religion , but his main criticisms of the argument from design are all contained within a chapter of his Enquiry . He suggests that even if you acknowledge there is a strong analogy between natural objects and designed ones, it doesn’t follow that there is one personal God that designed them, or who carries on existing and interacting with the world. They could just as easily have been made by a bunch of lesser gods working as a team or a God that subsequently died. He toys with all kinds of ideas, not because he believes they’re true, necessarily, but because he says that from the evidence, they’re equally probable. He even entertains an idea that is quite close to evolution as a possibility. It’s a very clever unraveling of a certain style of argument by analogy. “He doesn’t get obsessed with his skepticism” There’s also a brilliant essay on miracles, and whether you ought to believe the testimony of somebody who claims to have witnessed one. It turns on the idea that a miracle is a transgression of a law of nature. You’ve got huge amounts of evidence that if somebody says that somebody rose from the dead and walked about that the witness was mistaken, that there’s been misreporting. He gives some psychological accounts of why that might be so. His line is, ‘always believe the lesser miracle’. It’s a lesser miracle that someone was confused or conned than that somebody did actually arise from the dead. His conclusion is you shouldn’t believe eyewitness testimony that a statue has wept blood, or whatever the miracle might be. This was very controversial in his time and has been much discussed ever since. Those are just examples of the sort of ideas he has. Hume has a wonderful personality that comes through his writing. It’s a playful personality. You have to work to get through some passages. The books is quite difficult in parts because of the 18th century prose, but it’s worth persevering with. It’s also very easy to find commentaries on Hume to help you through that, including an amazing website originally made by Jonathan Bennett called Early Modern Philosophy , which includes complete paraphrases of huge number of philosophical works in contemporary language, including Hume’s. It’s different for different people. What you can’t miss is just how intelligent he is and creative in the way he presents counterarguments and examples. He loves creating imaginary situations which allow you to understand what’s at stake and why a particular argument has gone too far in its conclusion. He’s got a very fertile mind. And he’s quite genial. There are jokes in it, which is quite unusual for philosophy. He’s somebody who’s very skeptical, but what’s attractive about him is he’s not saying, ‘you can’t really believe anything.’ Crudely, what he believes is that there’s a point where you can’t push reasoning any further and we fall back on our human nature. Rather than worry too much about it, he goes off for a walk or plays backgammon. He doesn’t get obsessed with his skepticism. He’s a mitigated skeptic, as he puts it, rather than someone who says, ‘I can’t be sure I can take a step forward because I might fall into the abyss.’ He pushes arguments as far as they’ll go, but when he can’t resolve something, he’s not tearing his hair out. In answer to your question, a very attractive person comes through. His contemporaries mostly liked him, except those who hated him for his anti-religion, as they saw it. People don’t read him because they believe empiricism is true because very few are going to be taken in by his system. They read him because he’s a fascinating, intelligent thinker, trying to get to grips with things and has some brilliant arguments within that, some of which do hold still, particularly in the area of religion. This is the famous argument about the problem of induction. How do we know the future will be like the past? Just because the sun has come up every morning so far doesn’t mean it’ll come up tomorrow. Arguing from patterns of past events aren’t like deduction: we can’t be sure those patterns will hold in the future. Arguments from induction involve accumulating a large number of cases in support of continuity. Deduction, on the other hand, is where you say something like, ‘All men are mortal, Socrates is a man. Therefore, Socrates is mortal.’ If the premises are true, the conclusion must be true. It’s 100% true if the premises are 100%, true. A deductive argument is a truth-preserving machine. Induction is more problematic. How can we rely on induction—as we do. This is what science relies on, this is what we do in our daily lives. We assume patterns of similarity carrying on in the way that we’ve discerned in the past? How can we rely on such an unreliable way of reasoning? Bertrand Russell’s example is about a turkey who wakes up every day until Christmas Eve, when it then gets its neck wrung. The turkey had this justified belief, using inductive arguments, that the future would be like the past, but it absolutely wasn’t. That fateful day it wasn’t fed by the farmer, instead it was taken out and killed. How do we know we’re not in that same position in relation to the sun rising and any number of inductive conclusions that we draw? I step out of my office, I expect to be in my garden, but how do I know I’m not going to be in London? Just because I haven’t been in the past it doesn’t follow that I won’t be in the future. Hume tries to look at that, he looks at questions about cause and effect as well, and dissects them. What is it for one thing to cause another? Is it some kind of mysterious power that’s transferred from one thing to another? Or is it just finding the two things together in a certain sort of pattern? He analyzes that very systematically too. These are very deep, philosophical questions that he brought into sharp focus in the Enquiry , but originally in the Treatise . As I said, in almost everything like this, where he gets to a paradoxical situation, he says we have to rely on our own human nature in the end, the patterns of understanding the world we’re born with. This is where he’s a skeptic, philosophically. You push the skeptical arguments as far as they’ll go, and you can’t guarantee that the sun will rise tomorrow by inductive reasoning. You cannot find a warrant of induction that will be entirely reliable. Many people have tried since. It’s disconcerting, but you fall back on human nature at a certain point: we just do stuff. That’s more or less what Hume says—that or go and play backgammon. Most of us take for granted that we can rely on induction. We take for granted we know what we’re talking about when we talk about causes of things. If a billiard ball hits another and the second one moves, we say the first one caused the second one to move. But what do we mean by that? Just that whenever the first one hits the second one, it will move? It’s kind of mysterious, what we mean by it. And Hume teases that apart and looks at it analytically. That is a fundamental question in science, identifying cause and effect and what we mean by causation. Hume is incredibly important at opening up significant questions and putting forward arguments and thought experiments to demonstrate what he meant that have been the hugely discussed since. Just as an aside, if anybody does catch the Hume bug, his life is absolutely fascinating. There’s a great biography of him written in the 1950s by Ernest Mossner , which I think is better than any subsequent biography of Hume, though others have come out since. He was a fascinating man, so I’d recommend that strongly. There’s also a fascination section in Michael Ignatieff ‘s book The Needs of Strangers where he describes James Boswell visiting Hume while he’s dying, and the conversations they had and the significance of Hume’s death as an atheist in a religious age. Boswell, as a Christian, doesn’t believe Hume is really going to his death without fearing it, but Hume seems quite happy with the sorts of arguments that Epicurus and Lucretius used about why you shouldn’t fear dying, even though they didn’t believe in any kind of afterlife, or any separable soul. Hume didn’t seem to either. It’s a lovely summary of a real deathbed scene with the characters of Boswell and Hume in stark contrast."

"Yes. I was at that stage, a college sophomore or thereabouts, when you’re searching around, looking for belief systems. I think it’s actually a point when you’re quite vulnerable, because you are looking for someone who is going to offer you all the answers. Some people turn to religious orthodoxy, other people turn to Ayn Rand. One of my favourite lines – and I haven’t been able to find out who came up with it – is that “There’s an age when boys read one of two books. Either they read Ayn Rand or they read Tolkien’s Lord of the Rings . One of these books leaves you with no grasp on reality and a deeply warped sense of fantasy in place of real life. The other one is about hobbits and orcs.” “My purpose is not to find better ways of making money, although I have no problem with people doing that. My purpose is actually to make a better world.” Then I read Hume’s Enquiry , this wonderful, humane book saying that nobody has all the answers. What we know is what we have evidence for. We do the best we can, but anybody who claims to be able to deduce or have revelation about The Truth – with both Ts capitalised – is wrong. It doesn’t work that way. The only reasonable way to approach life is with an attitude of humane scepticism. I felt that a great weight had been lifted from my shoulders when I read that book. I felt the pull of them. You look at people who are very certain, and have these beliefs of one form or another and you think, “Maybe they really know something!” And what Hume says is, “Actually, no. They don’t.” In my experience with these things – which I find both within economics and more broadly – is that if you ask a liberal or a saltwater economist, “What would somebody on the other side of this divide say here? What would their version of it be?” A liberal can do that. A liberal can talk coherently about what the conservative view is because people like me actually do listen. We don’t think it’s right, but we pay enough attention to see what the other person is trying to get at. The reverse is not true. You try to get someone who is fiercely anti-Keynesian to even explain what a Keynesian economic argument is, they can’t do it. They can’t get it remotely right. Or if you ask a conservative, “What do liberals want?” You get this bizarre stuff – for example, that liberals want everybody to ride trains , because it makes people more susceptible to collectivism. You just have to look at the realities of the way each side talks and what they know. One side of the picture is open-minded and sceptical. We have views that are different, but we arrive at them through paying attention. The other side has dogmatic views. That’s hardly true of Keynes . What a deeply reasoned piece of work that book is! And I don’t think it’s true of someone like me. Yes, I do have feelings, but take a look, for example, at the debate that’s playing out over healthcare right now. I’d like to say I bring in evidence. I’m not saying, “Here is the way the world ought to be, so it must be that way.” I try to show how different systems work. But then the question is whether it’s feasible. What does it take? This is the right thing to do, but how do you do it? It’s a combination of modelling it, of looking at evidence from other systems, of looking at evidence from our own system. And provided the thing [The Patient Protection and Affordable Care Act] isn’t overturned in the next couple of years, provided we can make it to 2014 when the system is fully in place, it will become a completely natural feature of American life. It’s not the system I would have designed if I didn’t have to worry about the politics, but I’ll take this highly imperfect system."