Very well, I'll bite.

I didn't really want to bring evolution into this, but logic exists because it was an evolutionary advantage. At one point, reasoning such as "A squirrel was gathering edible nuts in a pile here, but they're gone now; there is no trace of them being eaten; they must have been hidden somewhere" translated to a survival advantage, allowing those who used such reasoning to procure more nourishment and procreate more effectively.