Bell draws a distinction between crimes of passion and premediated murders, making it clear that for him, the person who chooses to murder deserves a harsher punishment, like the death penalty, precisely because there is deliberate choice involved in premeditated murder.

Llewelyn thinks it's a mistake to take the surviving Mexican drug runner a jug of water, but he chooses to do so, anyway. Why does he make this choice, even though he thinks it's a stupid one?

There's a lot of meaning packed into Cormac McCarthy's short, simple sentences. This example shows us Llewelyn's determination. In fact, you could use this sentence to describe Llewelyn's actions in almost any of chapters of the book. Except the ones where he's dead.