言うか？言わないか？どちらでしょうか？Why do 馬鹿を言うな and 馬鹿を言え have similar meanings?


It seems to me 「馬鹿を言え」 and 「馬鹿を言うな」 are pretty much interchangeable.
Corresponding expressions in politer form also exist, 「馬鹿を言いなさい」 「馬鹿を言いなさんな」
So what nuances of meaning do they each have? And what's the difference, if
any?

Why do they have similar, if not completely overlapping, meanings when one
tells the listener to stop and the other says the opposite? 馬鹿を言うな seems
pretty straightforward as a command telling the other party to stop with the
nonsense, but what about 馬鹿を言え? This phrase appears nothing but
counterintuitive. When someone says 馬鹿を言え, what kind of response do they
expect from the listener?




I'm not a linguist, but I think this expression has "if you could" implicitly.
「（言えるものなら）馬鹿を言え」"Tell me the nonsense (if you could)", which implies that the
speaker believes the opponent should not tell.

