Actually, given the ad hoc nature of discussion on the web, the notion of
'agency' has not really been defined thus far during this string, and of
course, neither has 'stupid'. I do believe that the onus of defining
'stupid' should be left to others who introduced it and accepted its use (I
envy you not).
I didn't introduce anything, but perhaps the sense of 'stupidity' Foucault uses in his brilliant review of Deleuze's logic of sense and difference & Repetition (theatricum philosophicum)?
part of relevant section:
"Intelligence does not respond to stupidity, since it is stupidity already vanquished, the categorical art of avoiding error. The scholar is intelligent. It is thought, though, that confronts stupidity, and it is the philosopher who observes it. Their private conversation is a lengthy one, as the philosopher's sight plunges into this candleless skull. It is his death mask, his temptation, perhaps his desire, his catatonic theater. At the limit, thought would be the intense contemplation from close up-to the point of losing oneself in it - of stupidity; and its other side is formed by lassitude, immobility, excessive fatigue, obstinate muteness, and inertia - or, rather, they form its accompaniment, the daily and thankless exercise which prepares it and which it suddenly dissipates. The philosopher must have sufficiently ill will to play the game of truth and error badly: this perversity, which operates in paradoxes, allows him to escape the grasp of categories. But aside from this, he must be sufficiently "ill humored" to persist in the confrontation with stupidity, to remain motionless to the point of stupefaction in order to approach it successfully and mime it, to let it slowly grow within himself (this is probably what we politely refer to as being absorbed in one's thoughts), and to await, in the always-unpredictable conclusion to this elaborate preparation, the shock of difference. Once paradoxes have upset the table of representation, catatonia operates within the theater of thought." (190)
'Stupidity' here is the operative outside of philosophical thought and is therefore a kind of indirect philosophical resource. This would be opposed to 'error' which is the domain of the reactionary 'scholar' (ie having a 'correct' understanding or 'representation' in the 'theatre of thought'). So playing the game of truth and error badly with a certain kind of stupidity has a pedagogical function, ie getting 'foucault' wrong and reading his work against the grain can be productive.
Arguably this is what has happened with his Iran writings, and the only person who seems to have understood anything sensible from them has been the master contrarian Zizek. Zizek's stupidity should be applauded!