Why do we believe?
Every morning we expect the sun to appear over the horizon. But according to the philosopher David Hume our expectation is wholly irrational. Why is it irrational? Because we only think the sun will rise tomorrow because we've made an induction (ie: we assume that because the sun has always risen before it will rise again) And we only think that induction is a reliable method of discovering information about the world because of another induction (ie: we assume that all of nature is uniform because the little bit of nature we have seen is uniform) As Hume argues it's circular to use induction to justify induction, and therefore we have no basis whatsoever for believing anything at all about the unobserved. (though many have tried I don't know that anyone has yet managed to defeat this argument.)
So, you might ask: If the thought is so very irrational, why do we all continue to believe that the sun will continue to rise?
Hume had an answer for that, too. He wrote that when we are exposed to a regular pattern we have no choice but to believe the pattern will continue. It's how we're wired. This explanation of the belief gives us no reason to think the belief is actually true, but it explains why we can't shake it.
Matan Torah
My belief in matan torah, though not based on a pattern or an inductive argument, is similar in that I can't escape it. My upbringing and education have conspired to produce a human being who believes that a nation of people - my ancestors - saw the great fire and heard the admonishing voice from Sinai. It's how I am wired.
There are no grounds for my belief in the revelation: No evidence or argument exist to support it. In fact, I have no rational reason whatsoever to think that this belief is true; nonethless I can't free myself of it.
Nor, do I want to.
[Acknowledgment: Those of you who have read Philosophy Gym, by Stephen Law, will recognize parts of this post. Those of you who have not read Philosophy Gym are missing out. You should pick it up at your soonest opportunity.]
UPDATE: In this post I wasn't judging anything. I was simply explaining why *I* believe what I can't prove. Those are *MY* reasons. I never said that they were GOOD reasons for believing. Just that they were MY reasons for believing. (there are no good reasons for believing, btw) This is what my detractors refused to understand. I wasn't claiming that my reasons for believing were as valuable as a formal proof. I didn't say it was a GOOD reason, just that it was MY reason.