TENET, while being an enjoyable spy-thriller, is not so good science fiction. It is also not so good philosophy, but it has its moments.
Unlike an inverted non-sentient object such as a bullet, a human being who is inverted (negation) and subsequently de-inverted (negation of the negation) has a knowledge of and through the process that the original linear version does not have.
Unlike the bullet, the human has the capacity for an apprenticeship of time, learning to abandon linear thinking and to think otherwise, to think in non-linear terms.
This non-linear thinking permits the resistants to make efficient use of the « temporal pincer ». Yet they remain only executants of the actual: « what happens happened ». This is the domain of inverted causality, not of retroactive causality.
A further step comes from not just knowing one’s presuppositions (Neil) but from the ability to posit one’s presuppositions. This is the passage from executant to Protagonist. Speculative retroactive causality cannot be reduced to scientific inverted causality.
Semantically, the passage from executant of the actual to protagonist of the virtual is presented in the action image, as executed. Syntactically, the speculative protagonist of the film as executed is Nolan himself.