I’ve been thinking a fair bit about the epistemology of philosophy recently. And I find it helpful to think out the possible positions by comparison to possible positions on the epistemology of perception. Here, crudely, are four positions one might take about perception.

1. Scepticism – Our perceptual evidence consists of non-factive mental states. (Perhaps it is the existence of those states, perhaps it is our beliefs about those states; the categories I’m interested in don’t discriminate along those lines.) And those states don’t give us sufficient evidence to warrant belief in propositions about the non-phenomenal world.
2. Idealism – Same as scepticism, except that the propositions we pre-theoretically thought were warranted by perceptual evidence are, in some sense, about the phenomenal world.
3. Indirect Realism – Our perceptual evidence consists of non-factive mental states and those states do give us sufficient evidence to warrant belief in the non-phenomenal world.
4. Direct Realism – Our perceptual evidence consists in factive mental states. (This includes views on which the evidence is the existence of the state, and views on which the evdience is the content of the state.) Since our evidence consists in facts about the non-phenomenal world, we have non-inferential warrant for propositions about the external world.

There are lots of different ways in which people draw the direct/indirect realism distinction. See, for instance, “this paper”:http://consc.net/neh/papers/copenhaver.htm by Rebecca Copenhaver for a number of different ways the distinction is drawn. Note in particular that my indirect realist doesn’t require that we represent the existence of mental states in perception, let alone the existence of non-factive mental states, let alone believe that we have non-factive mental states, let alone have those beliefs be the basis for beliefs about the non-phenomenal world. If I token _that’s a table_ in my “visual representation box”, and that tokening justifies my belief that that’s table, that counts as indirect realism for me. (Assuming that the visual representation box does, or at least could, include falsehoods.)

I make no claim that my usage here is in keeping with traditional usage, only that it’s one helpful way to divide up the categories.

Note that one can have different views about different sense modalities. One could be a sceptic about colour, an idealist about smell, and a direct realist about spatial vision, for instance. More interestingly, I think there’s an interesting view that is indirectly realist about most perception, but directly realist about touch. The motivation for this comes from (of all places) Descartes. Here’s something Descartes writes towards the end of the “sixth meditation”:http://oregonstate.edu/instruct/phl302/texts/descartes/meditations/Meditation6.html.

bq. I remark, besides, that the nature of body is such that none of its parts can be moved by another part a little removed from the other, which cannot likewise be moved in the same way by any one of the parts that lie between those two, although the most remote part does not act at all. As, for example, in the cord A, B. C, D, [which is in tension], if its last part D, be pulled, the first part A, will not be moved in a different way than it would be were one of the intermediate parts B or c to be pulled, and the last part D meanwhile to remain fixed. And in the same way, when I feel pain in the foot, the science of physics teaches me that this sensation is experienced by means of the nerves dispersed over the foot, which, extending like cords from it to the brain, when they are contracted in the foot, contract at the same time the inmost parts of the brain in which they have their origin, and excite in these parts a certain motion appointed by nature to cause in the mind a sensation of pain, as if existing in the foot; but as these nerves must pass through the tibia, the leg, the loins, the back, and neck, in order to reach the brain, it may happen that although their extremities in the foot are not affected, but only certain of their parts that pass through the loins or neck, the same movements, nevertheless, are excited in the brain by this motion as would have been caused there by a hurt received in the foot, and hence the mind will necessarily feel pain in the foot, just as if it had been hurt; and the same is true of all the other perceptions of our senses.

There’s an interesting principle here. The principle is that if we get evidence through a chain, then what evidence we get supervenes on the qualities of the last link in the chain. I’m not sure that’s right, but for the sake of developing a position, let’s say that it is. If that’s right, it follows that vision, for instance, can’t be understood the way the direct realist wants to understand it. For if the light between me and my computer (the chain through which I get visual knowledge of the computer’s properties) were altered by a malicious demon, so the computer changed but the light immediately around me stayed the same, I would get the same evidence. But that evidence would not consist in facts about the computer, for I would represent what I actually represent, and this would now be false. So we get very quickly led to indirect realism about any form of evidence that arrives through a chain.

Now for Descartes, all our evidence arrives through chains or cords of one kind or another. That’s because all our evidence has to get to the brain, and thence to the pineal gland. But perhaps that’s false. If we’re good Ryleans, and think that we (as opposed to our brains) gather evidence, then perhaps tactile evidence is not really mediated. If my hand touches my desk, there is nothing between the hand and the desk that mediates the connection. So perhaps we can be direct realists about tactile perception. Note that Descartes’ dualism isn’t doing much work in this argument; what is doing the work is that thinking takes place in (or through) the brain. And that’s a much more widely held view. But arguably it isn’t right; arguably thought, or at least representation/evidence collection, takes place at least throughout the nervous system, and perhaps throughout the whole body. Or so we’ll assume.

The theory we end up with is largely indirect. We have direct evidence that the external world exists. We can touch it. (Note the prevalence throughout history of thinking that touch gives us especially direct evidence of the external world. We refute idealism by _kicking_ the stone, not looking at it.) But we don’t get a whole lot else. Most of the details require filling in by evidence that is indirectly related to its subject.

Coming back to philosophy, all four of our positions are well represented in the contemporary debate.

The sceptic is the person who thinks that we have at best indirect evidence, i.e. intuitions, for philosophical theses, and these are not good evidence for the claims we want.

The idealist thinks that we only have intuitions, but that’s good because the desired conclusions were largely conceptual in nature. The idealist, that is, thinks philosophy is largely an investigation into the nature of concepts, so facts about mental states, i.e. intuitions, are a perfectly good guide.

The indirect realist thinks that philosophical questions are not, or at least not usually, about concepts. And she thinks that our evidence is largely intuitive, and hence indirect. But she thinks that, when we’re doing philosophy well, these can provide warrant for our desired conclusions.

And the direct realist thinks that all three are wrong about the nature of evidence. We start with evidence that bears directly on the questions we’re interested in. We simply know, and hence have as part of our evidence, facts like the fact that a Gettiered subject doesn’t know, and that torturing cats for fun is wrong. There isn’t any need to worry about the link between evidence and conclusion since the evidence often entails the desired conclusion.

Williamson’s “The Philosophy of Philosophy” is largely an argument for direct realism in philosophy, an argument that often proceeds by attacking the other views. So chapter 2 is a direct attack on idealism. Chapter 7 is an attack on indirect realism, with some attacks on scepticism thrown in. And the sceptic is the subject of criticism throughout the book, especially in chapters 5 and 7.

I think the position I want to end up holding is something like the position on perception I outlined above. Direct realism is partially true. Some of our philosophical evidence consists of knowledge, not of non-factive states. (For instance, our knowledge that a vegetarian diet is healthy is philosophical evidence.) But this won’t get us very far, any more than touch alone gives us much perceptual insight into the world. Most of our evidence is indirect; it is intuitive. So I’m largely an indirect realist about philosophy

Holding indirect realism leads to two challenges. First, we must respond to arguments against indirect realism. The rough response I’ve been running in recent posts has been that the arguments against indirect realism are generally arguments against a very strong form of indirect realism, and we can hold on to a modified form without any cost. Second, we must explain how indirect evidence can bear on philosophical questions. That’s obviously the harder challenge, and one I wish I had more to say about.