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 which simply must be accepted without explanation? Consider the conjunction of all truths. Could this conjunctive truth have an explanation? Jonathan Bennett thinks not:

*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.

That is a cute little argument, one that impresses 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 theesome 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 if 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.

I agree with you here, and also suspect that explanatory rationalism ceases to be appealing when applied to practice. It seems to me that what explanatory rationalism would do in many a situation is lead to the philosopher's nightmare - the infinite regress.

If P is explained by Q (a seperate and distinct set of facts from P), then to be consistent as an explanatory rationalist, would you not have to hold that Q is explainable by R and R by S and S by T, etc, etc, etc,? If so, then there is no stopping. If not, then at some point, there must be a set of facts not itself explainable by appeal to some other set of facts.

In practice, one of the best examples of this are theological questions like: "Why is the world this way rather than that?" Any answer - "Because God is this way rather than that," for instance - provokes another "why" question and if one wants to, one can simply keep asking "why" to every answer ad infinitum.

Posted by: Kevin Currie | Thursday, January 15, 2009 at 04:17 AM

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.The worry is supposed to be that have not provided a contrastive explanation. We know that the conjunction is true iff. all of it's conjuncts are true. But the dialectical pressure comes from the question

why conjunction P rather than P+? That is, why this particular maximally consistent contingent conjunct (we might as well say, 'why this world?') and not another possible world? We have conceded that the world we inhabit is contingently actual. That concedes that another world might have been actual. That raises the question of why some other world isn't. Why this one rather than that one? There is a subtle shift in the kind of explanation sought, though, since now we are looking for an explanation in terms offinal causes. Leibniz offers the final cause that this world is actual because God aims at the best, and this is the best world. But I guess other final causes are available. The upshot is that, if we cannot offer a contrastive explanation (if there is no reason why this world is actual rather than some other), then all we can offer is the brute fact that it just so happens that this is the actual world or that's how chance would have it.Posted by: Mike | Thursday, January 15, 2009 at 07:32 AM

Hello bill,

Your argument is that it's adequate to explain the truth of the conjunction A&B by offering the separate truths A and B. I'm not so sure. P is supposed to be a conjunction of

contingenttruths. But from A, B there follows A&Bnecessarily. Offering A and B does nothing to explain thecontingencyof A&B. For this we need an explanation of the contingency of A and B individually, something more than their mere truth.Posted by: David Brightly | Saturday, January 17, 2009 at 03:57 AM

Hi David,

Let C = A & B. If one or both of the conjuncts are contingent, then C is contingent. Suppose we ask: Why is C true? My claim is that we can explain why C is true by simply saying that each of its conjuncts is true. We can say the same with respect to P: it is true because each of its conjuncts is true. (I don't see that it matters whether we take P to be the conjunction of all contingent truths, or whether we take P to be the conjunction of all truths both contingent and necessary. Either way, P will be contingent. Note also that if P were necessary, the question why it is true would lapse. What cannot be otherwise has its explanation in itself.)

You say, "But from A, B there follows A&B necessarily." That's right, but of course it doesn't imply that A&B is necessarily true. The necessity of the consequence is not the same as the necessity of the consequent. Same goes for P: given every truth, their conjunction P follows.

You say, "Offering A and B does nothing to explain the contingency of A&B. For this we need an explanation of the contingency of A and B individually, something more than their mere truth." I'm not getting your point. If the question is: why is A&B contingent, I say it is because its conjuncts are contingent. If you ask why A (or B) is contingent, I say that A records a fact that might have been otherwise.

Posted by: Bill Vallicella | Saturday, January 17, 2009 at 06:35 AM

Hi Bill,

Looking at my comment again I can see I haven't been very clear. For me, an explanation of the truth of A&B must involve an explanation of the truth of A and an explanation of the truth of B. It hardly seems adequate to say that A&B is true because A and B are true. Why is it true that am I short and fat? Well, because I am short and because I am fat! Hardly very

explanatory, surely? If asked toprovethe proposition A&B one would have to prove A and B separately, I think. I agree that "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." But then you move to "Similarly, it suffices to explain the truth of a conjunction toadducethe truth of its conjuncts." If 'adduce' means 'explain' then I agree, but I think you are using 'adduce' to mean 'state'.Posted by: David Brightly | Monday, January 19, 2009 at 04:50 PM