I want to discuss a type of argument which might be similar to what Kant called "transcendental arguments". (I'm not sure because I've never actually studied Kant. Must get on to that some day.) What I have in mind are those assumptions that we must make as a precondition to any sort of intellectual progress. Or, more generally, those things that we ought to believe because we've got nothing to lose by doing so. If they're false then we're screwed anyway, so we might as well just believe them and hope for the best. "Practical" might be a better label for this class of argument. After all, it's not as if the arguments do anything to establish the truth of the belief in question; they merely show that we might as well believe it.
The example I've used in the past is free will: If we can choose at all, then we must have free will. Therefore, anyone faced with the choice ought to choose to believe in free will. You can't possibly go wrong that way. Either you've got no choice at all, or else free will is the correct choice. Makes it pretty easy, don't you think?
This shows that we might as well believe in the preconditions for choice (namely, free will). For similar reasons, we might as well believe in the preconditions for rationality. Consider the laws of logic. I can't think of any non-question-begging justification for something so foundational as, say, modus ponens, or the law of non-contradiction. But we can't get anywhere without them. So we might as well just accept them, and hope for the best. (Thankfully, this seems to work.) The same goes for induction, and our assumption that the past is a reliable guide to the future.
Perhaps we should add in the notion of normativity (which I have difficulty getting a firm grip on). If there are normative truths, or facts about what we ought to do, then we ought to believe this. So either we ought to believe in normativity or else there aren't any facts about what we ought to do. So we can't possibly go wrong (i.e. against what we ought) by believing in normativity. Indeed, it's only by having this belief that we could possibly be doing what we ought to do. So, again, with nothing to lose, we might as well believe in it.
Is this good reasoning? Can you think of any more examples?