What makes people irrational thinkers?

[Belacqua]

Plato's allegory

Also I want to be careful with Plato's allegory. 

Like all allegories, it's an illustration, and breaks down pretty quickly if taken too far.

The idea that desire and the emotions are somehow discrete and separate parts of the mind, and that there is some objective rational observing "self" watching them from behind (like the chariot guy) is a cartoon picture. The parts aren't detachable, I think.

So it's dangerous to imagine that we can have calculation of pure reason, with the other parts tamped down momentarily.