The topic of explanatory rationalism has surfaced in a previous thread. So it's time for a re-run of the following post (ever so slightly emended) from nearly three years ago. How time does pass when you're having fun.

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Explanatory rationalism is the view that there is a satisfactory answer to every why-question. Equivalently, it is the view that there are no brute facts, where a brute fact is a fact that neither has, nor can have, an explanation. Are there some truths that simply must be accepted without explanation? Consider the conjunction of all truths. Could this conjunctive truth have an explanation? Jonathan Bennett thinks not:

Let P be the great proposition stating the whole contingent truth about the actual world, down to its finest detail, in respect of all times. Then the question 'Why is it the case that P?' cannot be answered in a satisfying way. Any purported answer must have the form 'P is the case because Q is the case'; but if Q is only contingently the case then it is a conjunct in P, and the offered explanation doesn't explain; and if Q is necessarily the case then the explanation, if it is cogent, implies that P is necessary also. But if P is necessary then the universe had to be exactly as it is, down to the tiniest detail -- i.e., this is the only possible world. (Jonathan Bennett,

A Study of Spinoza's Ethics, Hackett 1984, p. 115)

Bennett's point is that explanatory rationalism entails the collapse of modal distinctions.

The world-proposition P is a conjunction of truths some of which are contingent. So P is contingent. Now if explanatory rationalism is true, then P has an explanation in terms of a Q distinct from P. Q is either necessary or contingent. If Q is necessary, and a proposition is explained by citing a distinct proposition that entails it, and Q explains P, then P is necessary, contrary to what we have already established. On the other hand, if Q is contingent, then Q is a conjunct of P, and again no successful explanation has been arrived at. Therefore, either explanatory rationalism is false, or it is true only on pain of a collapse of modal distinctions. We take it for granted that said collapse would be a Bad Thing.

That is a cute little argument, one that impresses the illustrious Peter van Inwagen as well who gives his own version of it, but I must report that I do not find it compelling. Why is P true? We can say that P is true because each conjunct of P is true. We are not forced to say that P is true because of a proposition Q which is a conjunct of P.

I am not saying that P is true because P is true; I am saying that P is true because each conjunct of P is true, and that this adequately and noncircularly explains why P is true. Some wholes are adequately and noncircularly explained when their parts are explained.

Suppose three bums are hanging around the corner of Fifth and Vermouth. Why is this threesome there? The explanations of why each is there add up (automatically) to an explanation of why the three of them are there. Someone who understands why A is there, why B is there, and why C is there, does not need to understand some further fact in order to understand why the three of them are there. Similarly, it suffices to explain the truth of a conjunction to adduce the truth of its conjuncts. The conjunction is true because each conjunct is true. There is no need for an explanation of why a conjunctive proposition is true which is above and beyond the explanations of why its conjuncts are true.

Suppose the three bums engage in a *ménage à trois*. To explain the *ménage à trois* it is not sufficient to explain why each person is present; one must also explain their 'congress': not every trio is a *ménage à trois*. A conjunction, however, exists automatically iff its conjuncts exist.

Bennett falsely assumes that "Any purported answer must have the form 'P is the case because Q is the case'. . ." This ignores my suggestion that P is the case because each of its conjuncts is the case. So P does have an explanation; it is just that the explanation is not in terms of a proposition Q which is a conjunct of P.

I conclude that Professor Bennett has given us an insufficient reason to reject the Principle of Sufficient Reason.

I apply a similar critique to Peter van Inwagen's version of the argument in my "On An Insufficient Argument Against Sufficient Reason," *Ratio*, vol. 10, no. 1 (April 1997), pp. 76-81.

"Someone who understands why A is there, why B is there, and why C is there, does not need to understand some further fact in order to understand why the three of them are there."

I'm not sure this is true. Suppose that whenever I pray to God for a sign there always follows a peal of thunder. We can have good explanations for my praying in terms of my psychology, etc., and good explanations for the thunder thanks to physics, but don't you think such occurrences would nevertheless be evidence for the existence of God? But if so, then it looks like there is some further fact here for which God is introduced to account for.

I think a better way to respond to Bennett/van Inwagen is to say that it isn't necessary for P to explain Q that P entail Q, and that some necessary propositions do just that: explain without entailing.

Posted by: Matt Hart | Thursday, December 15, 2011 at 12:46 PM

Matt,

You are not getting my point. I am not saying that every whole of parts is such that explanations of the parts amount to an explanation of the whole. I am saying that this is true of SOME wholes, and that the whole which is a conjunction of propositions is like this.

Posted by: Bill Vallicella | Thursday, December 15, 2011 at 04:18 PM

Bill,

I did miss your remark to that effect, but that makes your bum example rather misleading.

Here's another argument (or maybe it's just a rephrasal), assuming that probabilities deal in propositions:

The Pr(A & B & C) will always be less than the Pr(A), Pr(B), etc. taken individually, if we say that none of their individual probabilities equal 1 or 0. But then the probability of the conjunction may have such a low probability that the explanations given individually can't be held responsive to it.

Posted by: Matt Hart | Thursday, December 15, 2011 at 11:32 PM

My bum example seems entirely apropos. Why misleading?

And what does probability have to do with this?

Posted by: Bill Vallicella | Friday, December 16, 2011 at 05:27 AM

This is a bit off topic, but I was wondering how I could contact you, Mr. Vallicella. I found some articles on Charles Dickens that you might find interesting (in response to the Defense of Scrooge post).

And please tell me that your endorsement of Scrooge was tongue-in-cheek! Surely one who spends his life pondering the universe, traveling the world, and experiencing this piece-of-work that we call Mankind would agree that a life of cold, bitter loneliness is far too high a price to pay for profit!

And have a Merry Christmas, or Happy Holiday, or I'm sure you're not offended by either. I can say that I am very lucky this year to have found this blog and it's thoughtful posts, but that's enough brown-nosing for one day.

Posted by: Jim | Tuesday, December 20, 2011 at 05:27 PM

Merry Christmas, Jim. You can find my e-mail address on my site. You just have to look for it. Gotta go.

Posted by: Bill Vallicella | Wednesday, December 21, 2011 at 04:46 AM