Monday, December 7, 2009

The evidence wars continue

Turri's False Evidence.

Weatherson's Evidence and Inference.

Will the truth out? Will truth out? We'll have to wait and see.

Some arguments (that might need some tinkering)

(1) If someone knows that p is part of her evidence, it seems that the question ‘Why is it that p?’ is appropriate/in place/proper/doesn't rest on a mistake in the way that 'Why do fish weigh less when they die?' is inappropriate/out of place/improper/rests on a mistake. That assumes that we’ll respond by saying either ‘No reason, it’s just a brute fact that p’ or ‘p because q’. Both answers entail p. I can't see how you could explain this unless you assumed that evidence is factive.

(2) If S knows that p is part of her evidence, she knows that p is true. If I know that p is part of S's evidence, it isn't an open question for me as to whether p.

(3) It seems that if A asserts that p is part of A’s evidence and then B asserts ~p, it seems that A and B disagree/can't both be right.

(4) If p is part of my evidence and I know that p is part of my evidence, I think I’m in a position to A for the reason that p (when I know that my choice to A is a p-dependent choice). You cannot A for the reason that p if ~p.

(5) It just sounds weird to say, ‘His evidence was that p, but of course ~p’ or 'His evidence was that p, but I don't believe p', but this cannot be weird for Moorean reasons because it's his evidence, not mine.

I've offered other arguments in the Synthese piece and in other posts, but I won't repeat them here.

13 comments:

Jonathan Ichikawa said...

Here's another argument -- have you used it before? If p is part of S's evidence, then for some q, S can believe q on the basis of p. Suppose S does this; then, S can truly say "I believe q because p". But this sentence entails p.

John Turri said...

1) "If someone knows that p is part of her evidence, it seems that the question ‘Why is it that p?’ is appropriate/in place/proper/doesn't rest on a mistake ..."

I think this is because p would serve as evidence only if you believe p. So the question is appropriate because you believe p.

Doesn't 2 just beg the question?

On 3, related to my response to 1, they disagree because A believes p, and B believes ~p.

You know what I have to say about 5. "Clayton's evidence for thinking that evidence is factive is that all evidence is non-inferential knowledge. But, as it turns out, not all evidence is non-inferential knowledge"!

John Turri said...

Jonathan,

"I'm disappointed because Dumbledore died." Does this sentence entail that Dumbledore died?

John Turri said...

(This is just to get follow-ups emailed to me. I forgot to tick the box before.)

Jonathan Ichikawa said...

John:

Yes.

Clayton said...

Wait, Dumbledore dies!?!

I'm on book 4! When does that happen?

Clayton said...

"1) "If someone knows that p is part of her evidence, it seems that the question ‘Why is it that p?’ is appropriate/in place/proper/doesn't rest on a mistake ..."

I think this is because p would serve as evidence only if you believe p. So the question is appropriate because you believe p."

I don't disagree that p is part of your evidence only if you believe p, but I don't think that the belief requirement on possessing evidence can explain the relevant data. The question is why does knowing that p is part of your evidence put you in a position to know that the right answer to your question will be either 'p because q' or 'it's a brute fact that p'? Without the factivity of evidence, I think we cannot explain that.

I wouldn't say that (2) begs the question if people just find (2) intuitive.

John Turri said...

Jonathan,

That can't be right, because it's false that Dumbledore died (one can't die without existing). And yet some people can truly say, "I'm disappointed because Dumbledore died."

John Turri said...

Clayton,

You're right, 2 doesn't beg the question. K might not be factive.

Jonathan Ichikawa said...

John,

As you know, the case of fictional truths is complicated, and a number of options are available. The problems you're raising are very general: there is pressure to treat true "Clayton now knows that Dumbledore died" (sorry Clayton!), but if we do, your argument will work against the factivity of knowledge. So maybe these 'disappointed' claims are literally false, or maybe there is a tacit 'in the fiction', or maybe it is true that Dumbledore died after all, perhaps in some kind of Meinongian way. All of these lines have been defended in the literature on fiction.

Note that this problem also generalizes against the view that evidence must be believed.

John Turri said...

Jonathan,

Right, the Dumbledore case should be handled with an implicit 'in the fiction'. Likewise "I believe q because p" can be understood with an implicit 'in my way of looking at things' or 'as I believe' inserted between 'because' and 'p', in which case (the proposition expressed by) the sentence 'I believe q because p' doesn't entail p, but instead only that I take p to be true.

This is good, since 'I believe q because p' doesn't seem to entail p, although it does seem to commit me to p.

Clayton said...

Jonathan and John,

I'd love to jump in, but I'm a bit tied up at the moment. Quick points.

Post was written in haste, but I think my sympathies are with Jonathan here.

(1) John believes that reasons are mental states because his intuitions differ from mine and he finds the arguments in his Nous article convincing.

That seems to entail:
(2) John's intuitions differ from mine and he finds the arguments in his Nous article convincing.

I can't see how (1) doesn't entail (2). It looks like denying that is to deny the factivity of 'because'. It might be that John is right in saying:

"I believe q because p" can be understood with an implicit 'in my way of looking at things'

But that's consistent with saying that 'S believes q because p' can be understood without that implicit restriction in place and I cannot think of a good reason to think that this restriction is always in place. When I try to explain why John believes what he does about reasons, I cannot see why I would implicitly restrict this to either my way of looking at things or John's way. I'm just trying to explain John's belief to someone who might not see things John's way (or my way).

John Turri said...

I think this is really interesting and important, so thanks, Clayton and Jonathan, for sharing your thoughts.

First, I believe the first person cases differ from the third person ones, which makes me think it's not entailment, but something pragmatic like commitment. Second, I also think that it's not too easy to detect whether the 'because' is occurring in an intentional context, such that the explanans isn't entailed. Finally, it's not clear that 'because' names the same relation in all these cases.

I might say (3) 'Clayton believes: q because p'. This doesn't entail p, because we embed the 'because p' into the content of the belief.

But suppose I say (4) 'Susan believes q, because p'. There's a better case to be made that this does entail p, although I'm not sold on that yet. If the 'because' here isn't intended to name the basing relation, but instead a simple relation of efficient causation, then I think there's an entailment. (5) 'Susan believes q, and she's caused to do so by the fact that she's genetically predisposed to believe such things'. That entails that Susan's genetically predisposed to believe such things.

But now consider (6) 'Susan believes q, and she does so on the basis that January is pleasant in Nunavut'. That does not entail that January is pleasant in Nunavut.