Why we can be rational but not nihilistic

The nihilistic view that there is no objective way to measure the value of anything is definitely unsatisfactory and self-defeatist, so that even extreme atheists do not appeal to rationalism alone.  At some point, most people recognize that while the human experience might not matter to the universe, it matters to humans, and that is a good starting place.

But even if we reject nihilism as a defining world-view, it is still possible to use it to justify the formation of any kind of belief, no matter how unmotivated it may be.  This is, I think, common ammunition against atheists, and against outspoken atheists in particular.  An atheist decries religion as irrational, but an astute theist can easily show, nihilistically, that the atheist's concern for rationality is itself irrational.  "So, you think it is bad for me to be irrational?  OK, then - by what objective standard do you say that irrationality is bad?"  Of course, there is no objective standard, and the atheist is shown to be, to some extent, irrational himself.  The atheist's concern for rationality is thrown right back into his face.

The presumption in this case is that all irrationality is created equal.  Nihilistically, I suppose that is true.¹  After all, if you say that being only a little bit irrational is better than being highly irrational, you are making a non-objective value judgment.  So the atheist cannot respond by saying, "well, I am being less irrational than you, and that is better."  In any event, that kind of playground response does not seem befitting for so deep a question.

There is something unsettling about appealing to nihilism to justify religious belief, if for no other reason than it is a somewhat paradoxical construction - "I am OK with my own irrationality because it is irrational for me to care that I am being irrational."  It is as if nihilism is recognized as the fullest extent of rationalism, and that there is therefore no real reason to care about being irrational, so that somehow, absolute rationalism cannot say anything bad about irrationality itself.  Weird.

The solution to the problem is, I think, to recognize that value judgments are a human invention, and to embrace the fact.  While nothing can be shown to objectively matter to the universe, things can definitely be shown to matter to people, to humanity.  Every possible question that we can ask, scientifically or religiously, is inseparably rooted in the human element - even reason itself is human.  To place rationality in a sphere where human beings are not part of the picture is to render it altogether useless.  Rationality, as a system of human thought, must recognize its human origins to avoid careening off toward nihilistic oblivion.

So, perhaps an atheist might defend his own irrational insistence that rationality has intrinsic value by appealing to the human experience itself.  The value of rationality stems from the human need for it.  This doesn't seem too hypocritical: if rational thought is a human institution (it is), then using the human experience to define value seems rational enough.  That's what I meant to suggest by saying that "the human condition matters to humans."

1. Actually, saying that all irrationality is equal is itself a value judgment that cannot be supported objectively.  It would be more proper to say that no amount of irrationality is demonstrably worse than another.