A person has what is known as 'character' and 'personality'. These words indicate discenable patterns of behavior. Determinism in this discussion means that a given person will 'behave in an expected manner'. Further feature of humans in that you can coerce them to behave in highly constrained manners.
Entire institutions and organizations in humanity are based on this feature of human beings.
A heuristic software agent that will respond in a spectrum of possible ways and past performance is no guarantee of future performance. It is no way reassuring that your agent has 'never done x' since if 'x is in the space of possible responses' it can certainly do 'x'.