What words describe a person who does not think well?

asinine, blind, brainless, crass, crazy, daft, delirious, demented, dense, dim, dizzy, doltish, dull, dull-witted, dumb, fanatical, fatuous, foolish, harebrained, idiotic, inane, ingenuous, insane, insensitive, irrational, lumpish, moronic, naive, nonsensical, obtuse, retarded, senile, senseless, silly, simple, slow, slow-witted, stupid, thick, thickheaded, undiscerning, unimaginative, unperceptive, unsound, witless, lacking in intelligence, mentally lazy,

What words refer to not being able to think well?

derangement, idiocy, imbecility, insanity, lunacy, madness, senility, stupidity,

What words refer to a person who does not think well?

airhead, blockhead, dolt, donkey, dullard, dumbbell, dummy, dunce, dupe, fanatic, fool, idiot, imbecile, moron, numskull, scatterbrain, sucker,