Certain Doubts

Gewirth answers the problem of the Cartesian Circle via the notion of psychological certainty. Cleaned up a bit, the best version of his view runs as follows. We first arrive at a clear and distinct perception that God exists and is no deceiver by inferring it from premises that are themselves clearly and distinctly perceived. We then define the epistemic notion of certainty in terms of there being no proposition that is a reason for doubting. Next, revising Gewirth a bit, we understand a reason for doubt so that X is a reason for doubt only if it is false that its negation is clearly and distinctly perceived. Then we note that the only reason for doubting clear and distinct perceptions is that God is a deceiver. From these premises it follows that all clear and distinct perceptions are certain in the epistemic sense.

Jim objects to this argument in the Cartesian context by noting that this epistemic sense of certainty is not Descartes’ notion of metaphysical certainty.
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Are there counterexamples to the following?

Where X makes Y reasonable, d is a defeater of this relation only if d’s being probable is also a defeater.

Here we are told that philosophers ought to look “pink-faced, white-bearded, rumpled, squinty.” I looked at our list of contributors, thought about what we all look like, and it doesn’t look good for us…

Can someone tell me why it is said that “other things being equal, the simplest theory is the best”?
I have some thoughts about it, but I’d like to hear what other people think.

Extra credit question: Is simplicity in philosophical theories a virtue in the same way (or in any way) as simplicity in scientific theories?

The department of Philosophy at CMU is organizing a summer school focusing on logic and formal epistemology. Information and instructions for application can be found at:

http://www.phil.cmu.edu/summerschool/

The school intends to expose undergraduate students to topics in the aforementioned areas. Thanks to the support of NSF the school is free! Informal inquiries may be directed to Jeremy Avigad (avigad@cmu.edu). Hope you can disseminate this info among some of your promising undergraduate students.

H.

Here’s an amazing situation. I’m in a room right now with DeRose, Warfield, Fitelson, Senor, and McGrath! But it’s not an epistemology conference…

Prompted partly by Olsson’s recent Against Coherence (OUP 2005), I’ve been thinking about the truth-conduciveness of coherence. There’ve been two recent claims to prove that coherence cannot be truth conducive (in Olsson, and Bovens & Hartmann’s Bayesian Epistemology).

I don’t know how many people have looked at this literature. Briefly, the claim (theorem, in fact) is that if

a) the coherence of a set of beliefs is a function of the probability distribution over the believed propositions and

b) the beliefs are formed independently of each other (i.e., when the truth-values of the relevant propositions are fixed, the occurrence of one belief doesn’t affect the probability of the other beliefs occurring),

then

c) there is no possible measure of the degree of coherence of a belief system on which more coherent beliefs are in general more likely to be true, ceteris paribus.

So I wonder a few things about this:

1) Is (c) incompatible with coherentism? Perhaps some coherentists would like to weigh in.

2) Should the coherentist accept (a) and (b)?

3) Lastly, I’m wondering more generally about the interpretation of claims like “x is conducive to y, ceteris paribus.” Olsson says that means: As long as you hold fixed all factors that are independent of x, an increase in x always leads to an increase in y. But I don’t think that’s right. This actually makes a big difference to the impossibility theorem.

Has anyone else thought about this?

Branden Fitelson is coming to Missouri next week to talk about the paradox of confirmation. It’s next Thursday, January 26, at 3:00 p.m. If you’re close enough to drive over (or down or up), do it. There has been too little epistemology this year for my tastes, so this will be lots of fun! Besides, it’s on a paradox, and it’s Branden! Stable the horses, shut down the still, and bring the folks!

P.S. If you’ll be coming for the talk, let me know via email–I’d like to make sure the room size is appropriate.

Consider two cases. In both cases, we have two hypotheses that explain data. For simplicity think of the data as data of sense. In one case, the hypotheses are a common sense one and a skeptical hypothesis. In the other, the hypotheses are two rival scientific explanations.

If you’re inclined toward common sense epistemology, you’ll be inclined to think that in the first case, the common sense hypothesis is justified (or made rational) by the data; and if you’ve got any understanding of how science works, you’ll hold that the data don’t confirm either theory in the second case. So, what’s the difference?

Peter Markie and I were talking about this question the other day, and he’s inclined to answer as follows. In the first case, the data prima facie justify the common sense view, and in the second case, the data do not justify either. The reason we find the two cases puzzling is that we are inclined to think there is a connection between justification and explanation, and though there may be, there isn’t enough of a connection to read off the justificatory facts from the explanatory ones.

Is this a good answer?

CD-er Vincent Hendricks has posted his new piece on epistemic logic at SEP here. It’s amazing what a valuable resource SEP is, and this article is another nice example of why.

UPDATE: I should have noted Vincent’s co-author on the piece, John Symons as well.