dimwitted doesn't fit. There are a great many holocaust deniers who are quite sharp.
I'm not claiming the man is stupid. I'm stating that these particular stances and statements don't seem to be a result of any vaunted intellectual process but more a reflection of belief, and as such, maybe not questioned at all... but maybe so. I know a great deal of people who I consider to be very smart, who sometimes don't have very intelligent opionions of certain things. I don't disclude myself from that statement.
OCWIATJ Forever