And St. Augustine beat Hume to his position by more than a century :) In The Righteous Mind Haidt actually quotes Hume's "Reason is, and ought only to be the s

And St. Augustine beat Hume to his position by more than a century :) In The Righteous Mind Haidt actually quotes Hume's "Reason is, and ought only to be the slave of the passions, and can never pretend to any other office than to serve and obey them." Given the above, I'm still happy with Haidt as a reference here, as he references Hume, and also has a decade or two of research to back up his claims.