Rationalism And Science

I've been thinking a bit about rationalism, empiricism and science, and I tried writing some notes to organize my thoughts about it. It's all pretty half-baked and unsatisfactory, but I've turned it in into something I can put here anyway, in case it's the kind of thing anyone likes to read.

Rationalism vs Empiricism

• Roughly: empiricists think knowledge only comes from experience, while rationalists think pure reason has an important role.
• Rationalists tend to think experience has some role too, although they might think that the kind of knowledge that involves experience isn't so good, or perhaps isn't knowledge strictly speaking at all.
• Empiricists sometimes think it's OK to get mathematical and/or logical knowledge from pure reason. Maybe you can get some knowledge of analytic truths that way too, although under the influence of Quine (and Morton White, usually via Quine) they might not think there are any properly analytic truths.
• If you want to firm up this second source of knowledge as part of your position, you can appeal to Hume's Fork. Hume's Fork is the idea summed up in this quote from the end of his Enquiry Concerning Human Understanding (emphasis in original):

  "If we take in our hand any volume; of divinity or school metaphysics, for instance; let us ask, Does it contain any abstract reasoning concerning quantity or number? No. Does it contain any experimental reasoning concerning matter of fact and existence? No. Commit it then to the flames: for it can contain nothing but sophistry and illusion."

  It takes some interpreting to get this passage to be arguing for exactly the empiricism-plus-maths-and-logic position, but it's in the ballpark. If you do adopt this package, you might even be able to get away with calling yourself a logical empiricist, like Rudolf Carnap. Carnap is very in at the moment, and is also generally considered to have been a great guy.

Descartes And Leibniz

• They were scientists and mathematicians, but they were also metaphysicians.
• As philosophers, we tend to look more at their metaphysics than their science, unless we're specialists. The science is more obsolete than the metaphysics (although perhaps not more wrong), science isn't really taught via 300-year-old texts even when it isn't obsolete, and we're not studying science anyway. And we're probably even less interested in reading their maths than in reading their science.

The Appeal Of Empiricism

• When you're reading their metaphysics, sometimes they will invoke principles of pure reason to derive their metaphysical conclusions. For example, Leibniz invokes such useful gizmos as the Principle of Sufficient Reason and the Identity of Indiscernibles. Descartes says things like there must be at least as much reality in an efficient and total cause as in the effect of that cause (from Desmond M Clarke's 1998/2000 translation of Descartes' third Meditation). And Spinoza, the other member of the Big Three rationalists, takes this kind of thing to a whole new level with an axiomatic presentation of his grand metaphysical system in the Ethics. You have to wonder what justifies their principles, and sometimes it can seem like they're just making up premises on the fly to get themselves out of an argumentative tight spot. I suppose this is particularly the case with Descartes, who makes things even worse by appealing to the light of nature, or the natural light of reason, and we often read Descartes when we're young and impressionable. Perhaps harping on about the natural light of reason makes a good impression on some young philosophy students, but it didn't make a good impression on me.
• The metaphysical conclusions that they derive aren't even especially attractive to a lot of us. The existence of God, the non-physical soul, pre-established harmony and so on. We feel like we could easily get by without them, and then we wouldn't have to accept the premises, or the embarrassing Light Of Nature methodology by which they arrived at them.
• Science, on the other hand, is an empirical discipline. We're quite sure of that. So while we might not know exactly what goes on across campus in the science departments, we don't really worry that anything of importance will be lost to science if we become empiricists. So we can keep science much as it is, while taking a suitably unenthusiastic attitude towards metaphysics, saying that metaphysical theses are either unknowable, or probably wrong, or Not Even Wrong.
• We can still do a little bit of metaphysics, criticizing theses for conflicting with our best science, or for being internally incoherent. And we can also sometimes have a go at offering an empiricist critique of some of the things scientists get up to, when we take them to be straying into metaphysics. The interpretation of quantum mechanics is a good source of material there, although it is often difficult for philosophers to understand the relevant science well enough to get taken seriously. (And even if they do understand the science, getting taken seriously still isn't a given.)

Pure Reason In Science?

• All this seems like a very nice package, but there's a fly in the ointment, which is that scientific methodology may actually include an awful lot of rationalism. Sure, it's an empirical discipline, in that scientists gather data and do experiments and so on. But they also spend a lot of time filling whiteboards with equations, and they're even known to have flashes of inspiration in the shower, as if their problem has been suddenly illuminated by the light of nature. (Archimedes' alleged eureka moment in the bathtub is not a good example of this, since his flash of inspiration was about his displacement principle, and one has experiences relevant to that in a bathtub. But it does happen to scientists working on things besides bathtubs too.)
• Empiricists do have resources to push back on this line of thought. They're still allowed to use pure reason for maths, and for logical inferences. Perhaps that's what's going on with the whiteboards and the flashes of inspiration, and so under closer examination it will turn out that scientists aren't doing anything outside the empiricist's rules.
• Now, the closer examination of actual scientific practice is something that has been done an awful lot by other people, under the auspices of history and/or philosophy of science. I blush to confess that I do not have much familiarity with any of this literature. If you do, then please do correct me if I'm wrong, because I'm going to make a naive pessimistic case that under closer examination what we'll find is that science is in fact a bit of a Cartesian free-for-all.

The Problems Of Induction

• Induction, roughly, is when you take some observations, find a general rule that fits the observations, and then apply that rule to make predictions about new observations. If it didn't work, then it'd be hard to see how science could work. But there are two reasons why it is hard to see how induction could possibly work.
• The classic problem of induction is the problem of justifying the idea that old patterns can be expected to persist at all. We set up the dilemma as follows. (It'll be based on AJ Ayer's presentation of the problem in chapter two of Language, Truth and Logic, although Ayer himself thinks the problem's very hopelessness makes it a pseudo-problem as traditionally conceived.) Either inductive reasoning is justified deductively or inductively. An inductive justification would point to how old patterns have persisted after being identified before, and this is itself a pattern we can expect to persist into the future. But this reasoning seems circular. The deductive justification is in bad shape too, on the grounds that there just isn't any logical inconsistency in patterns being broken. A coin landing heads twenty times in a row is consistent with its landing heads the twenty-first time, as an inductive reasoner would presumably predict, but it's also consistent with its landing tails the twenty-first time, providing a counterexample to any attempted deductive justification of induction.
• The new riddle of induction, which we have Nelson Goodman to thank for, is still a problem even if you can solve the classic problem of induction. This time the problem is no longer showing that patterns will persist, but deciding which patterns we should expect to persist. There are lots of patterns consistent with any dataset, and we will get different predictions depending on which patterns we identify. Of course, there are some patterns that humans identify more readily than others. But justifying this as anything more than a cognitive bias, while still working within the empiricist's rules, is difficult.
• Rationalists, as we've learned, can appeal to the light of nature to get themselves out of just this kind of tight spot. Can't justify induction inductively or deductively? Just appeal to the light of nature! Not sure which pattern is more likely to persist? Let the light of nature show you the way.
• This is of course a bit flippant. Rationalists do have resources to invoke premises when an empiricist would be in a tight spot, but they can't do this arbitrarily, at least not by their own lights. Are the resources you need to deal with induction the kind of resources rationalists would appeal to?
• I think they are, or could well be. To get a handle on why, consider Plato's theory of forms. One of the problems the forms are supposed to solve is how we can have knowledge of general things, even though we only experience particular things. Plato's idea is that knowledge of general things is knowledge of transcendent forms, which are somehow reflected in the particular things, and which we apprehend with the intellect rather than with the senses. Mathematical knowledge is knowledge of forms, but scientific knowledge is knowledge of forms too. Aristotle didn't think that forms were transcendent, but (as I understand it) he still thought that scientific knowledge was knowledge about forms, or essences if that's different, and that in any case these are apprehended by the intellect. The exact mechanism by which the intellect apprehends the forms is hard to pin down - Plato suggested we remember them from directly experiencing them before we were born - but the idea of scientific knowledge being knowledge of something general apprehended by the intellect has had real staying power, and is the kind of thing rationalists in particular are into.
• This gives rationalists a bit of purchase on the problems of induction. For the classic problem, the idea is that we can learn something about events before we observe them, because the same forms show up in those events as the ones we have already observed. For the new riddle, the idea is usually that not all rules are equal because some correspond simply to forms, and some don't. Not every gerrymandered property you might think of corresponds to a form, and the ones that don't aren't as likely to fit in robust generalizations.
• You can try to rerun the arguments against the rationalist if you like. How do we know that forms will carry on behaving the same way we're used to? How do we know which properties correspond to forms? Well, because we examine them with our intellects and discover which forms there are and that they behave uniformly. How do we pull that off? Good question! But it seems we do pull it off, since science works. Denying that it could possibly work flies in the face of the evidence, and denying that it could work this way risks begging the question against the rationalist.
• So, we've got an argument that science has a problem that rationalists have the resources to solve and empiricists don't. For that, we didn't need to look at the actual practice of science at all. But now things get a little trickier. I'm going to make two suggestions, neither of which I have the expertise to properly back up.
  • First, a large part of what Descartes and Leibniz liked about being rationalists was that it gave them the resources as scientists to respond to just this kind of problem.
  • Second, not much has changed. Scientists are still leaning heavily on roughly the same rationalist methodology that Descartes was into, and being wildly successful with it too.

How Descartes And Leibniz Did Science

• In the seventeenth century it was possible to feel really good about the prospects for science. The progress they were making made understandable a level of optimism that may only have been equalled before or since by physicists in the late 1920s. They really felt like they would soon have it all figured out, and that when they did the answers would be simple, beautiful, and powerful.
• Descartes and Leibniz also took it more or less as a methodological axiom that the world was nicely ordered along principles that could be understood and discovered by humans. This is an idea that goes back at least to Plato's Timaeus, and on some accounts goes all the way back to Thales and is what sets philosophers like him apart from the storytellers like Homer and Hesiod who came before him. The Stoics were big on the idea, it persisted in some form throughout the middle ages, and in the seventeenth century it was as popular as ever. It's an appealing idea, and people working with the idea keep making discoveries and building cool stuff, while sceptics just bring everybody down. When asked to justify this methodological axiom, neither Descartes nor Leibniz was above talking about God. Both of them thought that God in his goodness had given us rational faculties which when used properly would be able to get us significant scientific knowledge of the world. Leibniz in particular also thought that God's perfection meant that he would make the world excellent - the best of all possible worlds, as they say - and that we could work out what would count as excellent, and use this to guide our theorizing both in science and metaphysics.
• So, how do you do science with this attitude? Well, prompted by observations and guided by the light of nature, you come up with a beautiful, simple, powerful theory of how the world works. You make the theory nice and mathematical, and maybe come up with some new maths like calculus (Leibniz) or co-ordinate geometry (Descartes) especially for the purpose. You do experiments to test the theory. If the predictions are borne out, great! If not, maybe there's something wrong with the experiments. Or maybe there's something wrong with the theory. Eventually you come up with something nice that fits the results you're getting. And because the world does in fact conform at least approximately to the kind of principles that seem simple and beautiful to seventeenth-century optimists, the whole thing went swimmingly.

How We Do Science Now

• Basically what I want to say is that we do things much the same way. We might not think that's what we're doing, but it is. More or less.
• When scientists are explaining how science progresses now, they'll sometimes offer an account based on Karl Popper's ideas. I haven't read Popper, and I expect the scientists often haven't either, because the account isn't really very plausible and it'd be uncharitable to attribute it to Popper himself. Here's how it goes. Scientists look at the data they're already aware of, and they come up with a theory that fits. The important thing about the theory is that it be falsifiable, in that there are experiments they could do or observations they could make that would show that the theory was false. Then they do experiments and/or make observations. If the results are what the theory predicts, the theory is more likely to be true. If the results aren't what the theory predicts, the theory is false and so they go back to the drawing board.
• When pressed, people usually admit that this does not really reflect scientists' actual responses to data not fitting their theories. There might be something wrong with the experiment, or maybe the theory does predict it after all but there was something in the initial conditions you weren't aware of. A classic example is the orbit of Uranus: it didn't fit with the predictions people made for it using Newtonian mechanics and gravity, but that's just because they didn't know Neptune existed. Include the gravitational effects of Neptune and Newtonian mechanics and gravity aren't falsified after all. That's how Neptune was discovered, or so I'm told. (The hero of that story is Urbain Le Verrier.) They tried to pull the same trick with a planet inside Mercury, which they called Vulcan, but there it turned out Newtonian mechanics and gravity really were the problem, and Einstein's theory of gravity explains it much better. But there was a long time in between unsuccessfully looking for Vulcan and rejecting Newtonian gravity.
• OK, so let's put aside naive falsificationism. How does science work, then? Well, I'd suggest they do pretty much what Descartes did. You have a sense of the kind of data you're trying to fit your theory into, and then you make something up that you're happy with, guided by the light of nature. Your theory will have some blanks in it like the mass of the electron or whatever, and when you find some way of taking measurements to fill in the blanks, you do. Then you cling on to the theory like grim death in the face of both friendly and unfriendly data until finally you come up with something you're not quite as unhappy with. This account adopts some themes people tell you come up in Kuhn and Lakatos - I haven't read them either - and what it agrees with Popper about is that the whole process works much more smoothly if your theory is the kind of thing that data can be friendly or unfriendly to. (That's why it doesn't work so well for metaphysics, I suppose.)
• The account is a total caricature, of course. But I'm hoping it's a caricature of the actual practice of science, unlike naive falsificationism, which is a caricature of what some scientists imagine they must be doing because rationalism somehow doesn't seem hard-nosed enough. Now, while it might sound like I'm being a bit mean to scientists, that's not my intention. If the rationalists are right, then this could be exactly what scientists ought to be doing. And whatever they're doing, they seem to be doing it very well.

The Moral Of The Story

• Sometimes people give the rationalists a hard time. We do sort of acknowledge that Descartes, Spinoza and Leibniz were great philosophers - I mean, everyone says so, right? - but when we look at their philosophical systems what we see are bad arguments for false conclusions. It's all too easy to attribute this to a bad methodology, saying that the problem is that they were rationalists. Maybe we should ditch the light of nature, stick with empirical methods plus maths and logic, embrace science and be quietist about metaphysics.
• What I'm suggesting is that this line of thought has a great big hole in it, which we don't notice because we don't think of the rationalists as scientists. Or perhaps we do think of them as scientists, but don't think of that as relevant to their philosophy. But it is relevant. They were scientists, they were good at it, they did science as rationalists, and we're still doing that today. If you want to assess rationalism at its best, then don't consider it as a method in metaphysics; consider it as a method in science. That's the moral of the story. The question is, is it a true story?

What's Wrong With This Picture?

• I mentioned earlier that there's a lot of stuff here that I'm pretty ill-informed about. Maybe you thought I was being disingenuous, but I wasn't. There's a lot to learn here, and I haven't learned it. And if you have, you probably don't need me to tell you that. The evidence is right there on the page.
• Nonetheless, this is where I am at the moment with this stuff. From where I'm sitting, it looks like you can't really get anywhere in science as an empiricist, the actual practice of science bears this out, and the rationalists should be given a bit more credit for it. So, what might I be wrong about?
• First, I might be wrong about empiricism's platform. Maybe they've got some clever solutions to the issues with induction that I was worrying about. Or maybe they're willing to embrace a greater level of scepticism than I appreciate.
• Second, I might have Descartes and Leibniz wrong. I've read a fair bit of both, but there's an enormous amount left that I haven't read, and I do find the scientific practice they envisage all a bit mysterious. That's why I describe it in these scathing terms, before insisting that what I described is the tried and tested scientific method that built the modern world. I think we should have a fairly low prior that a method that sounds like that could build a world that looks like this.
• Third, I might have modern science wrong. Who knows what these people get up to? They don't even seem to know. But those historians and philosophers of science I mentioned before probably have some idea, and I could try checking some of that out. I could at least read Kuhn. Everyone reads Kuhn.
• Fourth, I might be wrong about something else. I don't know what. But the whole situation is very unsatisfactory, and I think I must be missing something.

Reading List

• So, I've got some reading to do! If you've got this far and you think I'm a doofus who should calm down and read X and then everything will become clear, then please point me towards X in the comments. In the meantime, here are some things I could look at.
• The logical positivists/empiricists in the first half of the twentieth century were often pretty clued up about science, but they were also pretty thoughtful and self-aware about their empiricism. So perhaps I should read some Schlick or something.
• I found a book in a second hand shop the other day by Daniel Garber called Descartes' Metaphysical Physics. I probably won't read it all, because I am a non-serious person, but it looks relevant and I'll probably read some of it.
• I could have a look at some of Descartes and Leibniz's more scientific stuff, and see how they talk about what they're doing.
• I've only got a pretty sketchy understanding of Plato and Aristotle's understanding of form and how it helps with epistemology, so I should probably read something about that.
• Like I say, I could read Kuhn, at least The Structure of Scientific Revolutions. I should probably read something by Lakatos too. Popper is less of a priority.
• I saw an NDPR review of a book called Platonism at the Origins of Modernity: Studies on Platonism and Early Modern Philosophy, and it looked like some of the papers in that would be relevant.
• Once I've got through that lot I'll probably be down multiple rabbit-holes, so for me to put anything else on the list now would probably be a bad idea. But if you can point me to anything that would sort all this out for me, I'm all ears.

Scepticism as a engineering problem

Regular readers may remember that a while ago I was getting interested in scepticism. It was Peter Adamson’s fault, really. Well, I’m still interested in it. And I think basically that scepticism’s true. Here’s a picture of me defending it:

That picture was taken over a year ago, and I still haven’t written the paper. But I thought I might write some blog posts about it. This is the first.

A while back I was reading Peter Unger’s book about scepticism, which is called Ignorance: A Case For Scepticism. You pretty much have to read it if you’re defending scepticism. This is what I thought of it at the time, followed by a response from Aidan McGlynn:

And he’s right: it is a frustrating book. I don’t know why Aidan found it frustrating, but my problem with it is that the central argument is a bit silly. He argues that a lot of words are absolute terms, which means they only apply to cases at one end of a spectrum. If something could be flatter, it’s not flat. If something could be squarer, it’s not square. And if you could be justified in being more confident of something, or if you haven’t ruled out the possibility of some evidence making that thing seem less likely, then you don’t know it. In a lot of cases we’d ordinarily classify as knowledge, I guess you can’t completely rule out some new evidence coming in that’d make you more or less confident, so I guess if knowledge is one of these absolute terms, then a lot of everyday knowledge ascriptions are false, just like most flatness and squareness ascriptions. Unger hits you with this argument quite early on, and you think he’s just softening you up. You think he’s presenting a silly argument that shows his conclusion is technically true, before getting on to the real argument, the serious argument, the one that shows there’s something really problematic about our epistemic situation. You want him to argue that we’re never justified in being really confident about things. But if he ever does, I must have missed it. It was frustrating.

Now, you might wonder how else an analytic philosopher is supposed to argue for scepticism. Scepticism is the claim that nobody knows anything, or can know anything, or something like that. So as an analytic philosopher you analyse the concepts involved to get a more rigorous version of the everyday claim, and then argue for the rigorous version, either from premises people already agree with, or at least from premises they’ll agree with after going through your thought experiments. If the conclusion you come to from this method isn’t that big of a deal, that’s the method’s problem. And Unger pretty much agrees with this, which is why he also writes books about how most analytic philosophy isn’t that big of a deal.

I think there’s another way of framing the sceptical problem though, which doesn’t involve analysing the concept of knowledge, and doesn’t rest on any particular analysis of it. The sceptical problem is basically an engineering problem.

Think of all the opinions that right-thinking people have. They have strong opinions about what time it is, what happened a day ago, whether humans are causing climate change, what the capital of Sweden is, roughly how old the universe is, what stars are made of, and so on. Maybe they’re certain of some of this stuff; maybe they’re just pretty confident. Maybe there are also some things that a right-thinking person will think is between 60% and 70% likely, or whatever. In any case, there’s a credence distribution that sensible people will roughly have. Think for a bit about that credence distribution, in all its glorious and wide-ranging detail.

Now think about your evidence. You can perceive a few things around you. You’ve got some memories. You can do some tentative experiments: trying to move around, or rearranging the objects on a table, or looking behind you or underneath something. You can bring some memories to consciousness, you can ask yourself questions and test your dispositions to respond to them. You can type things into Google and get some results, and you can read the results. You can do some sums or concoct some philosophical arguments. You can get up and go somewhere else and be presented with the evidence over there instead. Maybe you can’t do all these things, and maybe you can do a few other things. The point is that when you really focus on it, your evidence can seem pretty limited. It can sometimes seem consistent with the solipsism of the present moment. In spite of this, you’re supposed to have all these strong opinions about remote things. So here’s the problem: how do you get from just this, to all that?

It’s not an argument, really. It’s a problem. You’ve got some tools and some raw materials, and you’re supposed to be able to do something with them. Your mission, should you choose to become an epistemologist, is to figure out to get from the evidence in front of you to roughly the credence distribution of a right-thinking adult. It’s a kind of engineering problem. It’s Descartes’s engineering problem. Descartes claimed that he could solve it, that he could start from premises that couldn’t be doubted and end up with something firm and constant in the sciences. You can argue how far he really believed he’d succeeded, but that is what he claimed. A simplified account of one version of his explanation is that you can argue fairly simply from pure reason and the contents of your own mind to the existence of a benevolent god who wouldn’t deceive you, and so if you do science as carefully as you can then you can be confident of the conclusions. Most people agree with the sceptics that this doesn’t work, but don’t agree with the sceptics that nothing works. I don’t think anything works, and that’s what puts me on the side of the sceptics. At least, I think it puts me on the side of the ancient sceptics, and Hume in some moods and maybe Montaigne and people like that. (I don’t know much about Montaigne and people like that.) I’m not sure Unger says anything much in his book to indicate that he and I are on the same side, though.

You can’t solve the engineering problem by analysing the concept of knowledge differently, because it doesn’t really use the concept of knowledge. It’s couched in some concepts, of course, and maybe you can try to undermine the problem with a careful analysis of those concepts. But what you really want is a story. Something like Descartes’s story, except plausible. You can tell a story about the raw materials, saying that perception has externalist content, or that we have acquaintance with Platonic forms, or that we have innate ideas. You can tell a story about the tools we have for constructing things out of those materials, bringing in externalist theories of justification, or inference to the best explanation, or talking about evolution. Maybe you can look hard at the maths of probability theory and see if there are any surprises there. And probably some of this storytelling can be and has been done under the auspices of conceptual analysis - analysing the concepts of perception, or justification, or whatever. But at the end of it, if it’s not a story about how we get from just this to all that, it’s not an answer to scepticism. That’s the story I don’t think can be plausibly told. And if you can’t tell that story, then you need to tell a different story about how an epistemically conscientious person will behave. I’ll sketch some of that story next time.

Keeping up with the robots

Like all sensible people, I spend fair amount of time worrying about the robots taking over. Futurologists disagree about exactly when this problem is going to become pressing, but when it does, we’ll need a plan. So I’ve come up with a plan.

First I’ll outline the problem. It’s well within the capabilities of computers to program other computers, and robots can do things like build computers. The machines of the future may be able to build more and better machines without us getting involved at all. And if, as Descartes and even Dawkins sometimes seem to, you think that a designer could not design something more powerful than itself, you are wrong.

Now, there might come a point when the machines are better at designing machines than humans are. After that point, not only will each generation of designers have more to build on than their predecessors, but they’ll also be better designers. This will have two effects. First, technology will advance much faster. Second, the robots’ designs will be better than anything we can come up with, since they are better designers than us. Our puny weapons will be no match for their superior intellect, and the robocalypse will be upon us.

Here’s the solution. The problem was robots becoming better at designing new robots. To keep up with them, we need to become better at designing new humans. We need to use our knowledge of biology to produce better humans who will in turn be better at designing the subsequent generation, and so on. The robots’ powers will increase exponentially, but so will ours. This will give us a fighting chance in the Robagnarok.

Of course, this plan of mine evokes the twin spectres of eugenics and designer babies, and the subsequent generations of bioengineering geniuses will presumably evoke brave new spectres of their own. The reasons for not going down those roads are as strong as ever, and I don’t like the sound of growing old in that world at all. But unless we can think of something else, it may be our only chance. And since the sooner we start, the more likely we are to beat them, I think we'd better come up with another idea pretty quickly.