Julian Baggini has a good tribute to David Hume that appeared in Aeon.
This was an interesting and provocative quote:
"The best human beings have not been driven by ideology, moral philosophy, and certainly not logic. They have always been people who have put the response to human need above creed or doctrine. Indeed, the worst crimes have been committed by people convinced of a justifying moral principle."
Perhaps. But there are plenty of other heinous crimes committed for no moral principle at all.