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Sunday, November 21, 2010

Alexander Pruss on Self-evidence and the PSR

As long as I have seen it used, I've had no end of trouble interpreting the term "self-evident." The only way I know to make sense of self-evidence is to understand it as a kind of intuitive obviousness. So, when Alexander Pruss writes in one of his papers that he finds the principle of sufficient reason (hereafter the PSR) to be self-evidently true, I interpret him as having a strong intuition of it. Unfortunately, this cannot be all he means by "self-evidence;" for he speaks about it as if it were an objective property about which we can be correct or incorrect. So, on Mr. Pruss's view, if I do not find the PSR to be self-evidently true, then it follows that one of us is factually right and the other wrong. Yet on my interpretation, the difference in opinion amounts to varying intuitions. So, while we may disagree as to how to handle our often unique intuitions, we are not necessarily mistaken about having them or not having them. I shall not hesitate to point out, for instance, that Mr. Pruss commits a substantial error when he decides to trust his intuition uncritically, and urges others to do the same, but I do not dispute that the intuition is genuine (though I strongly suspect that in this case it is contrived).

It cannot be, then, that Mr. Pruss shares my own concept of self-evidence; but then how does he envision it? One might suggest that Mr. Pruss combines my own concept of intuitive obviousness with a standard detailing under which circumstances it is appropriate to accept such intuitions. So, Mr. Pruss might embrace an epistemic standard such that he would claim one ought to accept a proposition as self-evident if one has a strong intuition that it is true, and his standard justifies accepting that intuition. So a subjective element plays a role on this view also, which is consistent with Mr. Pruss's treatment, but the addition of an epistemic standard to our considerations provides an objective component about which we can make factual claims and thereby judge them as correct or incorrect. If this is indeed what Mr. Pruss has in mind, then the PSR is self-evident to Mr. Pruss because his epistemic standard permits or perhaps even compels him to accept his intuition that the PSR is true. In contrast, I am mistaken that the PSR is not self-evident to Mr. Pruss, because even though I lack his intuition, I should nevertheless acknowledge that, if only I shared the intuition, then I too would be epistemically justified in trusting it.

If this is what Mr. Pruss believes, then he clearly holds to a different epistemology than myself, and one which I am disinclined to accept. I don't see any reason to trust intuitions uncritically, which is what it seems like Mr. Pruss would have us do. This is not to say that I reject using intuitions at all; for I do believe that we are justified in employing intuitions under certain circumstances, most notably those when we lack the time or interest to examine their contents more closely. For example, suppose I wished to estimate the number of NIU graduates who attended the graduation ceremony with me in 2010. One way to do this would be to draw on my intuition of how many people I must have seen that day in gowns. I can even cross-reference that intuition with my additional intuition of roughly how many names I remember seeing in the program booklet. These appeals suggest to me that about five hundred graduates attended. If these intuitions are strong enough, and cohere well enough, then perhaps I am justified in accepting them. However, I submit that this acceptance must be tentative, and that more importantly it must yield to a critical examination. So, if I learn from the NIU website that there were over a thousand graduates at the ceremony, then even though my intuitions might strongly tell me that there could not have been more than five or six hundred, those intuitions simply do not stand up to the hard evidence against them. In this way, intuition is not exempt from critical examination.

What about the PSR, though? How can there be "evidence" against a principle like that? In response, I suggest that we have two very good reasons to reject whatever intuition we might have that the PSR is true. First, I believe that once we examine what constitutes an "explanation," and how we find such explanations, then it will become apparent that Hume's account is the only workable one available, and moreover that the PSR cannot be true on a Humean view. This contention, however, requires significant development and defense, and so it will not be convincing until I offer such a defense. However, there is a second reason to reject whatever intuition one might have that the PSR is true: For I submit that the only reason to trust intuitions at all is inductive---that they have proved useful in the past and are therefore likely to serve us similarly well in the future. If we can show, therefore, that some intuition differs radically in character from those intuitions which have proved generally accurate and reliable, then the inductive argument loses nearly all its force for that intuition.

Recall the graduation ceremony example. The reader very likely noticed that the intuition I described therein has a very different character than whatever intuition we might have regarding the PSR. In fact, a defender of Mr. Pruss might go so far as to say that the judgments I described of how many gowned participants I witnessed and how many names I saw in the program are so vastly different from what they have in mind that they should not be called "intuitions" at all---and they would be quite right at least to notice that manifest and extensive qualitative difference. However, if a PSR intuition should be so far removed from a graduation ceremony intuition, then this only serves to show us that we ought not misconstrue past successes of intuitions of the latter sort as inductively supporting unverified intuitions of the former sort. We therefore require inductive evidence which is compatible with our PSR intuitions, or else a non-inductive argument for trusting PSR-type intuitions. Yet I can find neither of these things.

I therefore suggest to those who regard the PSR as intuitively obvious that they reflect on their intuition by examining it thusly: Can we find any cases where an intuition of similar character to our PSR intuition has proved true or otherwise accurate? Keep in mind that unverified intuitions which have merely failed to be proved false or inaccurate will not do for an inductive argument. For myself, I can find none, and thus I am unable to construct any argument to support PSR-type intuitions. Mr. Pruss, on the other hand, believes that the law of excluded middle is self-evidently true, and his defenders might regard an intuition for it as having a similar character to the PSR. However, I contend that they are not similar at all; for the LEM deals with language, with which we have intimate and daily experience, and the PSR we mean to apply to the origin of the cosmos, a domain of inquiry foreign even to the experience of the best and brightest physicists. In order to make an inductive argument for the PSR of the sort we have discussed, we must find a class of intuitions which do not apply to everyday experience, but which exhibit a demonstrable pattern of accuracy or truth. This appears to me an unlikely result. In the mean time, it remains only to point out that we should not trust that which we have no reason to trust, and so on these grounds we may hold that no appeal to intuition will constitute justification for accepting the PSR, even on the part of the person doing the intuiting.

Of course, all of this presupposes that I have adequately captured Mr. Pruss's concept of "self-evidence," which is in no way assured. If I have not, then what does Mr. Pruss mean when he declares the PSR to be self-evident? I cannot answer that question, but whatever the case, it seems that he needs to further defend his position that he is justified, even if only from his subjective point of view, in accepting the PSR.


Jarrett said...

Hey, you know you can go to Alexander Pruss's blog and ask him what he means by the term "self-evident". In fact, you could show him your post and he'll be likely to respond to it!

It's important you have the same concept of self-evident and PSR as Pruss does -- as Pruss says about Hume, "As a result, it is far from clear to me that Hume has even grasped the PSR in the sense which I assign to it. And if not, then his failure to see it as self-evident is irrelevant. "

I think you are wrong to say, "In contrast, I am mistaken that the PSR is not self-evident to Mr. Pruss, because even though I lack his intuition, I should nevertheless acknowledge that, if only I shared the intuition, then I too would be epistemically justified in trusting it."

Pruss was clear that those who say that the PSR is not self-evident, while having an improper grasp of the PSR, would make the the statement [PSR not being self-evident] irrelevant. What's important is not sharing Pruss's intuition, rather it's sharing his definition/concept of PSR. If you don't share his definition/concept of PSR, then your "failure to see it as self-evident is irrelevant."

But, why take my word, when you can go straight to the source and ask Pruss himself. I'd go to his post (even though it's a couple years old, Pruss still replies to comments on old posts) about his piece that appeared in the Blackwell Companion to Natural Theology.

Hopefully, he'll respond back!

Alexander R Pruss said...

Have a look at my book on the PSR. You'll find a chapter on self-evidence, whose first section is helpfully entitled "A definition of self-evidence", and whose ninth section is entitled "What self-evidence could be". :-) The Amazon and Google Books previews might allow you to view those sections if the book isn't in your library.

hatsoff said...

Mr. Pruss,

Hey, thanks! I will definitely check that out soon. I also appreciate you taking the time to respond, since I know you must be busy. (I have to wonder how you heard about my blog though... ?)

In any case, I'll see about posting a follow-up to this once I've read the relevant sections of your book. If Google doesn't have it I can almost certainly get it through interlibrary loan.

Thanks again!


hatsoff said...

Mr. Pruss,

I see that on p190 of your book, you give the following definition:

A proposition p is self-evident if, necessarily, anyone who understands it correctly understands it to be true, and it is possible for someone to understand it.

If you take the PSR to be self-evident, then since neither myself nor certain associates of mine regard it as true, it follows immediately that we do not understand the PSR. But this puts a defender of the PSR in a curious position: No longer do we require a defense of the PSR, as we typically imagine such defenses. Instead we require a statement of the PSR which adequately communicates its content.

Now, I don't mean to suggest that the burden rests entirely on the PSR advocate. Certainly it is my job as well to do my utmost to try to understand the PSR as you envision it. However, the problem, on your view, seems to be a breakdown in communication rather than a dispute over whether or not the PSR is true, and both sides should recognize this. For you to persuade me, it is quite enough on your view to show me what the PSR is all about. If you can do that, then its truth will be self-evident in the way you define, and it shall require no further defense.

In the mean time, we should recognize that the self-evidence of the PSR, as you define it, is not itself a reason to accept the PSR, but only a proposed partial explanation for why it is we might happen to do so. Indeed, it is akin to saying that you can't help but take the PSR to be true, and that even if it were false, it would not be in your power to reject it, no matter what combination of reason and evidence should be brought against it. Given this position, you needn't hesitate to try to consider the possibility that you are mistaken. For if we can persuade you that the PSR is false, even for just a moment, then, provided your slip is not caused by a sudden deficiency in understanding (perhaps brought on by considering too seriously my wacky ideas), we shall have shown that the PSR as you accept it is not self-evident after all.

So, again, the supposed self-evidence of the PSR ought not be mistaken for epistemic justification, nor should it pose any barrier to doubt; whatever intuitions we have about the PSR need not be trusted. As long as we can agree on these points, I am satisfied.

Thanks again for your response! Please note that I will continue to read, time permitting, your thoughts on self-evidence, in case you think I have misunderstood that as well. Of course, I hope you consider my own points.