pig-headed (adj.)

also pigheaded; 1610s, "having a head resembling a pig;" 1788 as "stupid and obstinate, unreasonably set in mind;" see pig (n.1) + -headed. Usually, but not always, figurative.

A pig-headed man must be one, who, like a driven pig, always will do exactly the opposite to what other people--in the case of the pig his luckless driver--wish him to do, that is to say he is an obstinate man. [The Sedberghian, June 1882]