 It won't look for. Traedas Book 1 Part 4 is called, of the Sceptical and other systems of philosophy. It's not as long as Part 3, but it's very complex. And it's quite hard to understand what's going on. It's divided into these various sections. We've already seen this. ac mae'n dweud hynny i wneud i'r ddweud at ysgwrs 1 a 2. Felly y'r ddweud yn cael ei ddweud ydw i'r ddweud yn cael eu ddweud i ddweud y ddweud yng nghyrchu'r ddweud. Felly, i ddweud y ddweud, mae'n ffwrdd yn ddweud yn cael eu ddweud o'r ddweud ei ddweud. Dyma'r ffordd pwylltyn o'r ddweud yn cael y ddweud. Rydym here means reasoning, he is going to draw sceptical conclusions about our capacity to produce arguments that generate evidence for particular conclusions. And his focus is on the demonstrative sciences, as he calls them. Think of mathematics, which is the paradigm of such reasoning. So suppose we've got mathematical reasoning, we've got a piece, a mathematical argument and let's take for granted that the rules of mathematics are certain and infallible. So we're not here casting any doubt over the mathematical principles in themselves. Nevertheless, when we apply those principles, when we actually perform a mathematical argument, we know from experience that there's some chance we'll get it wrong. Maybe one time in a thousand, maybe one time in a hundred depends how accurate we are, but occasionally we all make mistakes. So when we're judging how much evidence is generated by such an argument, we have to factor in our own fallibility, the fallibility of our own faculties. Thus knowledge, and bear in mind again, human means knowledge in the strict sense here of absolute infallible knowledge, it degenerates into probability inevitably. Okay, so when I'm thinking how much confidence to place in a judgment that I've made on the basis of a mathematical argument, I have to correct it. We ought always to correct the first judgment derived from the nature of the object, that is, the mathematical judgment, by another judgment derived from the nature of the understanding. In other words, the faculty of reason derived from the fallibility of my own reasoning faculty. And then Hume says, well, it's not only in demonstrative arguments that we need to make this sort of adjustment, because in probable arguments too, our faculties are likely to get things wrong. So we've just made a probable judgment about our reasoning faculty. Okay, I've got this mathematical argument, that itself is a demonstrative argument, but then it's as it were degenerated into probability because I'm making a probable judgment about my reliability in assessing a mathematical argument. That's a probable judgment. Well, that's subject to error too. So I need to make another adjustment. We're obliged by our reason to add a new doubt derived from the possibility of error in the estimation we make of the truth and fidelity of our faculties. So I might have got that first estimate of my reliability wrong. Better make another adjustment. This decision, though it should be favourable to our preceding judgment, being founded only on probability, must weaken still farther our first evidence and must itself be weakened by a fourth doubt of the same kind and so on in infinitum. And even the vastest quantity must in this manner be reduced to nothing. All the rules of logic require a continual diminution and at last a total of extinction of belief and evidence. So the idea is that if we carry on making these little adjustments because there's uncertainty as it were all the way down, we're judging how accurate our faculties are and then judging that judgment and then judging that judgment, all of these things introduce a little bit of extra uncertainty and eventually however certain the original judgment was it disappears. Well I'm going to turn to see whether that's a good argument in a moment but let's first ask the question whether Hume accepts it. Does Hume himself accept his own argument? He does seem to think it's a good argument and therefore it seems a bit paradoxical when he goes on to say no I don't really accept it. Why not? Well it might seem through this argument that Hume must be one of those skeptics who hold that all is uncertain and that our judgment is not in anything possessed of any measures of truth and falsehood. It seems to undermine all evidence, even probable evidence reduces down to zero. So no argument is better or worse than any other it seems. But Hume says of course I don't really have that opinion. I can't have that opinion because nature won't let me have it. Nature by an absolute and uncontrollable necessity has determined us to judge as well as to breathe and feel. So here we get one of the clearest indications of what is called Hume's naturalistic response to scepticism. The sceptical argument is theoretically untouchable but nature stops us accepting it. Our natural judgment we can't help having beliefs even though theoretically we shouldn't. Nature defeats scepticism and we'll see that's a major theme of Hume interpretation. We'll be talking about that next time. Again a continuation of the passage putting it in very vivid terms. Nor can we any more forebear viewing certain objects in a stronger and fuller light upon account of their customary connection with the present impression than we can hinder ourselves from thinking as long as we are awake or seeing the surrounding bodies when we turn our eyes towards them in broad sunshine. I think it's quite interesting John Locke, when he's explaining self-evidence, intuition, he talks about the bright sunshine and how it, for example if we think about the proposition one equals one, two is greater than one, these intuitively true propositions, they shine on our minds with a force like sunshine, we just see them to be the case. And here is Hume saying well take any customary conjunction, say between seeing an object released in air and seeing the object fall, we're so used to seeing that again and again that if we actually see the cause we find ourselves irresistibly believing that the effect will follow irresistibly like the sunshine. Just like I can't look over there without seeing what's in front of me, no more can I resist inferring that the pen will fall when I see it released. Again, nature dominating scepticism and he suggests that the reason for he's put this dramatically sceptical argument, this extreme argument in here in the treatise is simply to confirm his hypothesis that all our reasonings concerning causes and effects are derived from nothing but custom and that belief is more properly an act of the sensitive than of the cogitative part of our natures. So he's appealing to this extreme scepticism about reason to back up his conclusions about probable inference and belief. He said that belief is more a matter of feeling than it is a matter of reason. It's based not on insight when we expect something to happen in the same way as it has in the past. It's not because we have any insight into the uniformity of nature, it's just because we find ourselves expecting it and irresistibly believing that more of the same will follow. And so he's saying that his argument here is essentially all part of the same project. That still leaves a question though, how on Hume's own theory does he escape this scepticism? Well, his answer is essentially that if we try to do refined reasoning, if we try to adjust our judgment according to the fallibility of our faculties and then we try adjusting that judgment according to the fallibility and again and again as we go down this iterative sequence we lose track, we can't keep going, we're not good enough at concentrating and so the influence of these judgments on the mind weakens and fortunately for us we're able to retain belief. And this is after all a fairly familiar phenomenon, if you come across a complex argument it can be very difficult to hang on to it, it will be much more easily influenced by simple intuitive arguments. He refers back to this in the conclusion of book one, that's a treatise 1477. He points out that according to this theory the only thing that's saving us from total scepticism because this is an extremely radical argument is what he calls a trivial property of the imagination. It just so happens this sort of thing about our imagination that we lose track of complex arguments. How lucky that is, if it weren't for that we'd lose all confidence in anything at all and this does raise serious doubts about Hume's theory of scepticism in the treatise. There isn't instability there because as we'll see next time there are resources in the treatise to try to build some sort of reasoned answer to the sceptic, but Hume here seems to be saying that there's nothing rational about it, in fact if you like there's something irrational about it, the fact that we simply can't hold on to complex arguments and if it weren't for that we'd have had it. It's therefore perhaps significant that in Hume's later work in the inquiry this particular argument disappears. It's perhaps along with personal identity the most important argument of the treatise to disappear from the later works, which suggests that perhaps Hume wanted a rather better answer. Let's now consider whether the argument is actually a strong one. Suppose I make a mathematical judgment, suppose experience suggests to me that I go wrong in such judgments around 1% of the time. Okay so I adjust my credence, I decide well I felt absolutely certain of the conclusion of this but since I'm bearing in mind that I go wrong one time in a hundred I'm just going to assign confidence 99%. If I had to bet I would treat it as having confidence 99%. But wait a minute that 1% estimate that may be wrong. Maybe I should make another adjustment. Okay suppose I make another or suppose it occurs to me to make another adjustment what am I supposed to do? I mean that 1% might be wrong but it might be too big rather than too small. It might actually be that my probability of error is less than 1%, not greater than 1%. So why should uncertainty over the 1% knock down my credence below 99% that's not at all clear. Also the very requirement for iteration seems dubious. Some defenders of Hume, there's a tendency naturally enough amongst Hume commentators whenever one finds a Hume argument that seems dubious. Since most of Hume's arguments are actually pretty good it's very tempting to try to find some way to get him off the hook. So there's quite an industry with arguments like this of finding interpretations that supposedly justify the argument. And one response to the point I've just made is to suggest that okay when you iterate you can't be sure that the judgment is going to go down and down and down. I mean you may have overestimated your probability of error rather than underestimated but if you go on correcting judgment after judgment after judgment the idea is that somehow the probabilities will spread and spread and spread and get more fuzzy until they spread over the whole range from zero to one. So you still end up with complete uncertainty. Now it's going some way beyond the text I think but the text is so short and unclear that maybe that would be an acceptable or at least a plausible interpretation. But actually I think the case for iteration is pretty weak. Suppose I make a mathematical judgment what probability is relevant? The probability that's relevant is how often I go wrong in that kind of judgment. And that's if you like a straight statistical question. 99 times out of 100 I get such judgments right. That's it. Who cares how good I am at making that judgment? Why should that matter? So it's not at all clear that it should go all the way down. From a God's eye point of view if you like there is a certain reliability that I have in such judgments and I may have a more or less reasonable estimate of that from experience I probably will. I remember getting those sorts of things right most of the time. Now the fact that I can't give an accurate estimate of that judgment doesn't seem to me to justify the claim that one ought to make a judgment about that and then a judgment about that and go all the way down. So I think Hume's argument in Treatise 141 doesn't work and I think it shows good judgment on his part that he dropped it after the Treatise.