Here, the word ‘foolish’ is more appropriate, the argument’s concern over a fool, may yet not be a foolish endeavor. There may be a philosophical benefit to be gained, which would negate the idea of it being foolish. The conscriptive idea ‘fool’ can not be negated, where’s a descriptive one ’ Foolish ’ can.
When someone says, 'He’s a fool ’ the phrase is a presumption. A presumption has to be verified, before it can be negated. But when someone else says, 'He acts foolish '( ly); no such validation need to be done. In practical syntax. ‘He is a fool’ has to be conjoined by a -because he is such a such type of person. Because is a causally necessitated validation. In ‘He acts foolish’ because is not warranted, nor is appropriate in usage, because validation of foolishness does not meet the criteria of a necessary extrinsic evaluation. If an intrinsic, self evaluation is made, such as ‘He acts foolish’ because he wants to be perceived as such, then we go back to
bad faith, or the lie of deception.
So, if the question reduces to ‘Why does he act this way?(foolishly)’ we are no longer in the realm of necessary truth vis ; implying a objective evaluation, but to a contingent one, begging the state of mind of the foolish actor.
But we are not after states of mind, rather, meaning of foolishness. This whole casual chain is defeated by
the X unknown of why an actor, be he a fool or not, acts foolishly. Therefore , the object of inquiry is not a foolish action, BECAUSE there can not be ascertained a definite cause.
On the other hand, one can presume idiocy, on bases of patent analogy, such as , because he is mentally challenged, or he is of a very low IQ, or he has a developmental disorder, etc. But all of these have to be objectively evaluated, versus acting silly or like a moron,does not necessitate such evaluation.