Monday, January 19, 2009

Evidence and armchair access (II)

In a previous post, I argued that the principle of armchair access carries with it a kind of problematic sceptical consequence. You cannot consistently accept the principle of armchair access and say that we have non-inferential knowledge of the external world. That argument, however, rested on two claims that a defender of AA would not accept (i.e., that evidence consists only of truths (ET) and that non-inferential knowledge of p's truth suffices for p's inclusion in a subject's evidence (NIKSE)). My initial response was to say that while a defender of AA might not accept these claims (a) these claims are not without motivation (not posted) and (b) it seems that these claims ought to be innocuous when it comes to issues having to do with scepticism. In this post, I want to show that dropping ET won't make the problem go away. The problem is also not resolved by dropping NIKSE. So, we really do have good reason to reject AA and that reason does not really depend upon ET and NIKSE. Here goes:

The problems I've suggested arise for those who accept AA will not simply go away if we deny ET or NIKSE. While I think the right response is to drop AA, I can’t imagine that this is the response that those who defend AA would recommend. Suppose that instead of denying AA someone recommended dropping ET instead. Problems can still be generated for AA. Suppose that your evidence includes the proposition that you have hands. It follows from this assumption and AA that:

(12) You should be able to know from the armchair that your evidence includes the proposition that you have hands.

Since knowledge entails belief, if you do know what AA says you can know, it follows that:

(13) You believe that your evidence includes the proposition that you have hands.

It seems that if you are minimally rational and reflective, if you believe that your evidence includes p, you believe, inter alia, that p is the case:

(14) You believe that you have hands.

It seems that if you are minimally rational and reflective, you will not both believe p and believe yourself not to know that p. So, having given the matter reflection you accede that you believe yourself to know that you have hands. So:

(15) You believe that you have hands and that you know you have hands.

Assume also that you believe the assumption crucial to the argument against evidential externalism:
(16) You believe that you cannot know that you have hands from the armchair.

Now our question is this. How can you square (15) and (16) with the additional claim that you should be able to know just on the basis of what you know from the armchair that your evidence includes the proposition that you have hands? It seems as if you acknowledge that you are committed to the truth of a proposition in virtue of what you take yourself to know from the armchair alone and yet you know that the truth of that proposition is not something that can be known from the armchair alone. If we agree that you should not believe what you believe yourself not to know, it seems you should not believe that you have hands just given what you know from the armchair and thus that you should not believe that the proposition that you have hands is included in your evidence. However, if you could know non-inferentially that you had hands, it follows from this and NIKSE that you should be able to know from the armchair that your evidence includes the proposition that you have hands. So, what are we to say? It seems that problems for AA arise given just the assumption that NIKSE is true. Rejecting ET will not make the problems for AA go away.

Now, the reader might say that the problem arises because we are assuming AA, NIKSE, and that it is possible for someone’s evidence to include propositions such as the proposition that you have hands. A moment’s reflection, however, and we should all appreciate that to deny that your evidence can include the proposition that you have hands is to force us to choose between the unattractive sceptical view that non-inferential knowledge of propositions about the external world is unattainable or NIKSE. So, it really does look as if acceptance of AA comes with a cost. It forces you to deny NIKSE. I think this is bad. There is a kind of sceptical conclusion we wished to avoid (i.e., that you cannot have non-inferential knowledge of the external world) and it seems exceptionally odd to say that this is best avoided by saying that we have less evidence than we initially thought having accepted that there is no further obstacle to the collection of evidence than having non-inferential knowledge of the truth of the propositions included in the evidence. Setting aside this sceptical worry, there is a further sceptical worry that we ought to consider. To deny NIKSE in order to save AA is to insist that all evidence is provided by introspection or reflection. It is, in other words, to deny that perception is a basic or autonomous source of evidence. On its face, it seems that a necessary condition on some source (e.g., perception, introspection, memory) serving as a basic or autonomous source of knowledge is that this is a source of evidence. If we cannot plausibly accept AA and say that perception provides pieces of evidence that introspection alone cannot, I have to confess that I am somewhat at a loss as to how I might then say that perception is a source of knowledge. To concede that perception is not a source of knowledge is to concede a lot to the sceptic.

No comments: