Alan Saunders: Hello, and welcome to The Philosopher's Zone. I'm Alan Saunders.

This is, I think, the first issue of the show for which I've brought a prop with me. You can't see it, but I can -- or at least I think I can, which is part of today's story. So let me tell you that it's a red apple. I can't prove to you I've got it here, I can drop it on the studio table, perhaps you can hear it.

So, to talk about apples and the subject of the epistemology of experience (we'll come to what that is very shortly) we're joined now from Canberra by Daniel Stoljar, Professor of Philosophy in the Research School of Social Sciences at the Australian National University, and Jim Pryor, Associate Professor in the Department of Philosophy at New York University.

Welcome to you both.

Both: Hi, Alan, Thank you.

Alan Saunders: Now we're talking about epistemology. Last week I had a letter from a listener who described epistemology as a forgotten part of philosophy. I must say that this was news to me, but Jim, there are a lot of people who haven't so much forgotten it as never found out what it is. So Jim, tell me what is epistemology?

Jim Pryor: Epistemology is the study of evidence and knowledge, the word 'episteme' comes from the Greek for 'knowledge', but more generally it's issues about when is one thing a good reason to believe something else.

Alan Saunders: Now a lot of what we're going to be talking about here will seem obscure to many people, or if not obscure, then perhaps pointless, or it's difficult to see what the point is. So Jim, what's the historical background to these issues? How do they arise and why do they matter?

Jim Pryor: Why do they matter? Philosophers have wrestled since the Greek times with how we can know that one thing is good evidence for something else, and it gets dramatised in this sceptical scenario, is the idea that maybe everything's just an illusion, maybe you're just a brain in a vat, like the characters in The Matrix, or you're just dreaming everything and none of this is real, and so philosophers have wrestled with that kind of sceptical scenario, trying to come up with an answer to it. But I think that the pay-off isn't so much that we're going to have something we can say to reassure people that we're not in those crazy scenarios, the pay-off is that we're going to understand better what counts as good evidence for something else.

Daniel Stoljar: The other thing to say is that epistemology is about the foundations of science. I mean if your scientific enterprise is just a fantastically successful thing, you want to ask why does it work, and what it's based on, and epistemology in a way deals with those foundational questions. So in a sense, nothing could be more important.

Alan Saunders: Well Daniel, I can see a red apple in front of me, and if you really want me to be careful, I suppose I might say that I seem to see a red apple in front of me, I think I see a red apple in front of me. Isn't that caution enough for a philosopher?

Daniel Stoljar: Well it would be enough, but one wants to know not simply facts about your own psychological states, like whether you seem to see one, but one wants to know what kind of justification there might be for the claim that there is one, which is a claim about an object that's independent from you and independent from your mind. And after all, most of the world does have that status, it is independent from you and independent from your mind, and we want to know various facts and properties about that external world.

Jim Pryor: The main thing that people say is, 'Look, if you were just dreaming this, you'd be having exactly the same experience'. So the fact that you're having the experience isn't a guarantee that there's really an apple out there. If it's not a guarantee that there's really an apple out there, why should we think that it makes there being an apple out there more likely than not. It's not like you have run scientific studies in the past correlating when you seem to see an apple and when there's really an apple there and found out that most of the time there really is an apple. You haven't done that.

Alan Saunders: The interesting thing here is that these claims to knowledge appear to be normative. You see, there are two kinds of claim and two kinds of law in the world: the descriptive and the normative. The law of gravity doesn't tell you that you ought to fall to the ground if you throw yourself out the window; it simply tells you that you will. In other words, it's a descriptive law. The Ten Commandments, on the other hand, tell you what you ought to do; these are normative laws. Now the interesting thing is that the claims we're talking about now, they tell you that if you are in a certain psychological state, there are claims that you ought to believe, so they appear to be normative. Daniel Stoljar.

Daniel Stoljar: Yes, I think there is that issue, I mean as Jim said a minute ago, epistemology is about the notion of a reason in some sense, and a reason seems to be a normative claim. It seems to be that if you have a reason for something, or a reason to believe something, that in a certain sense you ought to believe it. So there's a normative claim in the offing, rather like normative claims that we see in ethics say, where we say we ought to act in a certain way. And so if you say that having an experience as of a red apple entails a certain claim about justification, say, that you're justified in believing that there is a red apple, then it looks like a psychological fact, namely that you having experiences of a red apple, entails a normative one, that you ought to believe, or that you have a reason to believe that there is a red apple. And the interesting thing about that is that traditionally, a sort of traditional piece of philosophy was that there's no 'ought' from 'is', you can't derive an ought claim from an is claim. And so here it looks as if we have some necessary connection or entailment between a psychological fact and a normative fact, and if so, that's an amazing situation, and so we find that connection between a descriptive fact and a normative fact right at the heart of epistemology where normally we don't find it there, we find it in ethics. So that's a remarkable observation.

Alan Saunders: Yes, we should explain about deriving an 'ought' from an 'is'. In the 18th century the great Scottish philosopher David Hume argued that from any description of a state of affairs you can't derive a set of instructions as to what you ought to do if you find yourself in that state of affairs. You might see somebody attacking a small child, but it doesn't follow that you're obliged to do anything about it, unless you add to the mix some other non-descriptive element, moral laws about what you should do in circumstances like this. And that's where we normally expect this sort of issue to arise. We don't expect it to arise in epistemology, do we?

Daniel Stoljar: Well, I don't think we've seen it arise in epistemology. I mean we don't expect it to arise perhaps, because we don't think of epistemology as being connected with action in quite the way ethics is connected with action.

Alan Saunders: Jim, isn't it reasonable of me to argue that the mere fact that I have an experience as of a red thing, puts me in a position to believe justifiably, that there is a red thing?

Jim Pryor: I think it is reasonable. That's in fact my view, but it's a crowded field, and there's lots of people who would counter knowing a position to reasonably believe that if you've got some background story. Consider, a neighbour moves in, and the neighbour has a tattoo, and you think 'Oh, so he's probably a stockbroker', people would say 'Why do you think that? What entitles you to believe that tattoos are connected with stockbrokers?' You'd need some kind of background story justifying that bridge step. And so some philosophers would say in this case too, you find that you had this experience, why are you out to go beyond that, some view about the outside world? You need some justification for this bridge step, too. So I'm on the side that you voice, that just having the experience is enough to justify you in believing that the external world is certain way. But as I said, the issues are complicated.

Alan Saunders: This is an idea that's inspired in part by the British philosopher of the first half of the 18th century, G.E. Moore, who was a friend of the more famous Bertrand Russell. Tell us, Jim, what he had to say.

Jim Pryor: Moore had several arguments against a sceptic. One was that the sceptic will try to give you a story about why you're not justified in believing that there's an external world, but whatever story the sceptic tells us is going to rely on some premises, and the claim that we're not justified in believing that say, we have hands or that there's a glass if you're an apple, is just so incredible that whatever the sceptic tries to come up with to establish that we're not just right in believing these things, it's just going to be much less worthy of belief than the commonsense propositions the sceptic's trying to overturn.

Another argument Moore gave was: of course I can know that I have hands; I just hold them up in front of myself, I see the hands, and that's enough to know that the external world is there, contrary to what the sceptic's suggesting.

Alan Saunders: There are a couple of things I want to ask you about this. One of them is: what do philosophers mean when they talk about the external world? What's it external to?

Daniel Stoljar: Well I think it means logically external from the mind, and from mental facts in general. It doesn't mean outside of us in a certain sense, I think it means logically independent from psychological facts. So an apple, let's say, is something which exists independently of our minds and in that sense is external to our mind, and the external world is just the sum total of objects like that, at least to a first approximation.

Jim Pryor: Your stomach and your brain would count as part of the external world by this philosophical way of thinking.

Alan Saunders: Jim, you said that G.E. Moore's argument that he knew he had hands was that he just raised a hand and there was a hand. Now, as early as the 17th century, the great French philosopher Rene Descartes would say, Well you think you see a hand, but how do you know that's a hand? He would even say, because he knew about phantom limbs, you know, you have a feeling of a limb, even though it's been amputated, he would even say you think you feel a hand, but there isn't a hand there. So, G.E. Moore seems to be ignoring an awful lot in what he says.

Jim Pryor: It's complicated what exactly Moore was trying to do with this. It comes in a discussion actually where he's more concerned with whether objects like apples are external objects or whether objects like apples are ideas in our minds. He's not primarily addressing the sceptic here; it's just that he's said things which have suggested or response to the sceptic. So I think it's hard to say exactly what Moore thought he was up to, but philosophers take away from Moore this kind of cartoon view. Samuel Johnson is reported to have said, Bishop Barclay was arguing that everything is just an idea in our mind and Samuel Johnson is reported have kicked a stone and said, 'I refute Barclay thus'. And I think people think of what Moore has offered this debate as something along those lines. But whether that's what he really thought he was doing, I'm not sure.

Alan Saunders: Daniel, I might doubt whether there is an apple in front of me, but I can't doubt, can I, that I'm having an experience as of an apple in front of me.

Daniel Stoljar: Well that's certainly the traditional view. That was Descartes' view. He thought, as you said a minute ago, that it was more cautious to say that 'I seem to see that there's an apple in front of me', rather than 'There is an apple in front of me'. And what's lying behind that I suppose is the idea that you can't doubt that it seems to you that there's an apple in front of you. But actually in contemporary philosophy there's a sort of an argument which suggests that in fact it's a little bit unclear how you come to know that you seem to see an apple in front of you. And the thought is that roughly that if you seem to see an apple in front of you, that's some sort of contingent fact about the world, it's a contingent fact which may or may not obtain; it's not a fact like 2 + 2 = 4. And when you think about contingent facts like that, it looks in general as if you come to know them in one of two ways: you either perceive directly that they exist, or you know that by inference, let's say, by reasoning from your perceptions, or perhaps from testimony, something like that.

But in this case, it seems completely unlikely that I came to know that I seem to see an apple on the basis of perception, or inference; I didn't see my seeing that I'm seeing an apple; I didn't catch myself seeing it, or something like that, and nor did I know it by inference. If you know something by inference, it suggests that you know something antecedently, and then you infer to some other kind of belief, and that doesn't seem to be a plausible model of self-knowledge at all. So there is a general problem about self-knowledge, which in a way runs counter to the Cartesian view that knowing that you seem to see something is always a piece of certainty. It's very difficult to see how you would come to know, in that sense.

Alan Saunders: This seems odd, because it's difficult for me not to believe that I have what's called a privileged access to my own experience. You might happen to know, or think you know, that there is no apple in front of me, but surely only I can know whether I think there's an apple in front of me?

Daniel Stoljar: Well it doesn't seem right that only you can know that. For one thing, if you tell me that you seem to see an apple in front of you, then I'm by and large going to believe you if I regard you as a kind of trustworthy person. That looks like a perfectly reasonable way of coming to know that somebody else has a certain experience. But it does seem to be the case that when you think about your own mental states, that's not the way that you come to know that you're in them. You don't come to know that you're in a mental state by the testimony of others or by observing anything; you come to know something directly. So I guess this argument that suggests that there's a problem about how you come to know that you're in a certain mental state isn't supposed to suggest the sceptical conclusion exactly, that somehow we don't know whether we're having pains or seem to see a red thing. But the argument is used to show that our model of how we come to know these things, our model of our introspective access, cannot be thought of as obviously perception-like, or obviously inference-like, it must be thought of in some other way. And the question is: what is that way?

Alan Saunders: Well there's a difference isn't there, between perception and other things that I might come to know. It seems to me to be perfectly reasonable for me to say, well I reflected on my own experiences and I realised, I came to know, that I was jealous of this person. But that sort of drawing of inferences is not the sort of thing that I expect to find in the area of perception. I don't come to know that I'm having or thinking I'm having a perception of something.

Daniel Stoljar: Yes, it can certainly be that for certain kinds of psychological states, like very complicated ones like whether you're jealous of a person, it may be that you come to know those by inference and by perceiving your own behaviour and by thinking about it and so on. But for certain simple cases like having an itch in your foot, or seeming to see a red apple, it doesn't seem to be plausible at all that that's the way you come to know those things. And so we seem to be faced with this odd situation, where the very psychological facts that Descartes and people influenced by him, thought of as kind of foundational, epistemologically. We seem to be faced with the fact that we don't obviously have a story about how it is that we come to know those simple facts.

Alan Saunders: Jim Pryor, let's talk about what it is to reflect on our own experience. Tell us about the diaphanousness of experience. What does that mean?

Jim Pryor: Diaphanous is a word that also comes from G.E. Moore. Moore had a passage where he says experience seems to be diaphanous, like a transparent curtain: you can look through it and see what's beyond, but it's difficult to focus on the curtain itself. So the idea is that when you look at the apple, you have an experience of the apple, but it's not like you're sitting in a theatre and looking at just some image on the screen and figuring out that there's an apple behind it. You don't seem to be aware of anything in between yourself and the apple, it looks like you're just looking directly at the apple. So if we want to talk about experiences in the story here, we have to be careful where we put them. They shouldn't be getting in the way like an opaque curtain between us and the objects themselves.

Alan Saunders: Is there a problem here Jim, presented by the fact that our observations might be as the saying is, 'theory-laden'? Explain to us what that means and what the implications of it are.

Jim Pryor: To say that your observations are theory-laden, means that what you observe, or what's the first thing you're allowed to conclude from the observations you make, can be affected by your background theory. There's a lot of psychological evidence. They run experiments like this: you show people, cardboard shapes, and you ask them to match its colour against some standards and if the cardboard shape is in the shape of a carrot, then people will tend to match it as more orange than they would have if the very same shape, which is in fact the same colour, was put a different way. So your thinking, 'Oh, this is a carrot shape' will tend to make it look more orange to you; the theory you have about the object, is affecting the way it looks to you.

Alan Saunders: And is this a problem? If I want to tell a story about how my alleged perceptions relate to reality? What sort of problem is it?

Jim Pryor: Many philosophers think it's a problem. I have doubts. But the story is that Look, how did the background views about whether this is supposed to be a carrot or whether it's supposed to be a shape representing an apple, how do those background views get a grip on what you're observing? One picture is: you have the experience, the first thing you're allowed to conclude is, Oh I have this experience. That's sort of like thinking Oh, the neighbour next door has a tattoo. And then you have to go from there, to a further step, reason about what the external world is like, and the theory can come in here and help you. And if you have different theories, it's going to point you in different directions. So if you have one background theory, you're going to think Oh, when I have experiences like this, there's probably a carrot out there. When I have experiences like this there's probably an apple out there. Different theories point you in different directions. That's the view.

Alan Saunders: Well you're both working quite hard on these issues as we speak, so I won't ask you exactly what you've concluded, but perhaps I could have a progress report about what sort of story we can tell about our perceptions. Let me begin with you, Daniel.

Daniel Stoljar: Well in my own case, the issues are more related to questions about introspection that we were discussing a minute ago. And there I think a position that's rather like Jim's position about perception, is extremely plausible, the idea that merely having a certain experience puts you in a position to believe that you're having the experience, that you don't need any further kind of access, any kind of introspective or perceptual access at that point. And the theoretical questions that arise there, are questions like: what could justify that claim that from the fact that you're having a certain experience, a certain epistemic fact follows. In philosophy, progress is often made by clarifying the issues and figuring out what questions to ask next. And here I think the question to ask next is: what is the relation between having an experience, and being justified in believing that you're having the experience.

Alan Saunders: And have you any idea what the answer might look like?

Daniel Stoljar: Well I think that the answer has to do with the nature of experience itself. Earlier we were talking about a psychological fact like having the experience, and an epistemic fact like having a reason to believe something. But if you think of the two things as more intermingled, then I think one can make sort of progress. So if you think of experience or conscious experience as itself somehow involving a normative element, then I think we can make progress in that way. So I think we need to think in a different way about experience than we've thought of in the past. We thought of it in the past as sort of an incredibly complicated psychological phenomenon, and of course it is an incredibly complicated psychological phenomenon. But if we think of it also as including a sort of normative element, then I think we might be able to work our way through this problem.

Alan Saunders: And Jim, what are you up to in the search?

Jim Pryor: Three questions I've been working on. One is, what is it for an argument to be questioned begging in a circular. So this cartoon argument people associate with Moore; so I can tell that they're external objects, because here's my hand, I can just see it. People think that that argument is question-begging, circular in an objectional way and so one project is trying to unearth what that charge amounts to.

The second project is about how all this stuff about the epistemology of experience and when your experiences give you a reason, how that relates to probability theory and issues in the foundations of statistics.

A third topic is that philosophers will think about experiences and they'll make certain claims: to have an experience you have to have such-and-such kind of cognitative architecture, or to have an experience of an apple, you have to have actually at some point in the past, come into contact with apples, otherwise how could you experience get to be about apples rather than some other fruit. So they'll make these claims about how the world has to be set up in order for you even to be able to have these experiences.

And then there are worries about if you have privileged access to what experiences you're having won't that mean perhaps that you'll have privileged access about the worlds being set up in these ways? But these are quite strong claims about how the world is, and it's surprising that we should have priliveged access about these strong claims.

Alan Saunders: If I could just take the second of your three issues, how could statistics illuminate these questions?

Jim Pryor: It's the other way around. So there are foundational issues in statistics that are relying on certain views about what's the right probability theory for us to be using, what's the right interpretation of the probability theory, and issues in general epistemology can help iluminate whether we made the right choices there in understanding how probabilities work and what kinds of probabilities to be using when we're doing science.

Alan Saunders: Well, Daniel Stoljar, and Jim Pryor, thank you very much for joining us.

Jim Pryor: It was a pleasure.

Daniel Stoljar: Thanks, Alan.

Alan Saunders: Daniel Stoljar is Professor of Philosophy in the Research School of Social Sciences at the Australian National University and Jim Pryor is Associate Professor in the Department of Philosophy at New York University.

The Philosopher's Zone is produced by Polly Richard with Technical production this week by Luke Purse. I'm Alan Saunders and I'm off to eat my apple.