Logic is the science of correct reasoning in any field whatever. But what are the foundations of its laws? Are they, as some have claimed, best viewed as "the laws of thought", laws grounded in facts about human psychology? Do they have their warrant merely in the conventions for linguistic behavior? Are they, as others have claimed, grounded in facts about reality more generally? Or are they, as still others would say, grounded in facts about how this and any other possible world must be? Let's take a brief look at each of these four views.