Mad Belief?

Mad belief -- in David Lewis's sense of "mad" -- would be belief with none of the normal causes and none of the normal effects. Such belief, I suggest, would not be belief at all. Delusions might sometimes be cases of beliefs gone half-mad -- beliefs with enough of the functional role of belief that it's not quite right to say that the deluded subject believes but also diverging enough from the functional role of belief that it's not quite right simply to say that the subject fails to believe.

So I say, at least, in an essay now available in draft on my website. (As always, comments, revisions, objections welcome -- either attached to this post or emailed directly to me.)

The essay is a commentary on Lisa Bortolotti's recent book Delusions and Other Irrational Beliefs, though it should be readable without prior knowledge of Lisa's book. You might remember Lisa from her recent stint as a guest blogger here at The Splintered Mind.