While reasons are provided by the facts,...rationality...depends instead on our beliefs. [...] [I]f I believe falsely that my hotel is on fire, it may be rational for me to jump into the canal. But I have no reason to jump. I merely think I do. And, if some dangerous treatment would save your life, but you don't know that fact, it would be irrational for you to take this treatment, but that is what you have most reason to do.