But people also have another trait--they want things to make sense. The Love of truth may be the weakest of human passions, but it still exists.
Because of this last trait, it seems to me that I should show how Torah is justifiable. [That means classical Torah--The Old Testament [Tenach], the Gemara [i.e. the Talmud Bavli].] But to justify Torah we have to go out of Torah into philosophy. This is how the Rambam/Maimonides did it, and Saadia Geon. You can't justify Torah on its own terms. To find a ground of justification, you need an external ground.
Since Reason has been in retreat in the Western World since the rise of Post Modern Philosophy, most people do not think that philosophy can justify Torah, and they also think they do not need Reason to justify it.
Now I should admit that my intention here is not to teach philosophy, but rather to explain why it is justifiable to sit and learn Torah [Gemara, Rashi, and Tosphot.]
To do this I can't use Aristotle like the Rambam did. I have to go to a modified Neo Platonic approach like Saadia Geon and the Chovot Levavot [Duties of the Heart] .
The intuitionist school of G.E. Morse and Prichard is close Kant school is better.
The Intuitionists are I think ignoring some of the real problems posed by Kant.
Now I get to the meat and potatoes of this discussion.
Frege wanted to expand the "a priori." [Things knowable by reason]. He wanted this to include all possible traits that can be derived from reason about objects of reason. The critique of Wittgenstein on this was true. But it was used by later incompetent philosophers to backfire on Kant himself and to deny the existence of the a priori and of metaphysics all together.
One example of a priori I would like to suggest is in mathematics. It is the number two. You don't literally stumble over the number two when you walk in the street. But few people would be inclined to deny its existence altogether. At least to deny it it would seem you should have some strong proof. At least strong enough to deny common sense. And it does not seem that my knowledge of the number two is dependent on chemical reactions in my brain. Let me ask you to complete this sequence: 2 is to four as 4 is to eight. Eight is to 16 as 16 is to 32. Then 32 is to 64 as ... fill in the blank. Is this dependent on what I ate for breakfast this morning? If so, then you, my dear reader who ate something different [I had eggs] would have to come up with a different answer.
[I should mention that one of the major ways that people that learn Torah think of it is as something that is applicable to Jews only. But this is clearly a mistake. Because objective values are by definition applicable to everyone and perceivable by everyone. And Torah does claim that it is objective.
And though many commandments are addressed specifically to Jews. still the value system of the Torah is universal. and in fact the Rambam says the Torah is for "anyone that wants it." [In the Laws of Gerut. keeping Torah in no way depends on getting other people to accept oneself. This is an open halachah in the Rambam.
Some people keep Torah as a means of social identity. And this is lamentable. Torah should be kept because it is true.