How would you build your rationalist assassin group?
To fit with exactly what you have up there, I see two options.
1) irrationality combined with extreme stupidity.
2) even more extreme stupidity.
I suppose you could hide the extreme stupidity under the “just smart enough to be dangerous to themselves” trope, but that still requires irrationality, which is what you’ve defined them to not want.
Probably better to abandon their aspiration to rationality and just make them clever extremists who desperately want to convince the world of their sanity. By not focusing on rationality you can get the viewer to also not focus on it.
To fit with exactly what you have up there, I see two options.
1) irrationality combined with extreme stupidity.
2) even more extreme stupidity.
I suppose you could hide the extreme stupidity under the “just smart enough to be dangerous to themselves” trope, but that still requires irrationality, which is what you’ve defined them to not want.
Probably better to abandon their aspiration to rationality and just make them clever extremists who desperately want to convince the world of their sanity. By not focusing on rationality you can get the viewer to also not focus on it.