Foolishness is a synonym of brainlessness.
As nouns the difference between foolishness and brainlessness
is that foolishness
is (uncountable) the state of being foolish while brainlessness
is the state or condition of being brainless.
(uncountable) The state of being foolish.
(countable) A thing or event that is foolish, or an absurdity.
* imprudence, folly
* extravagance, irresponsibility
* indiscretion, absurdity
The state or condition of being brainless.