[richard_todd]

I don’t see how the last sentence (the brain must model the environment) follows from the admission on the previous page that a regulator can skip the model by taking on unnecessary complexity. It seems there is a built-in assumption that the brain has no unnecessary complexity, if I am following correctly. I wouldn’t be so sure about that! (Although, I should add, the idea that the brain models its environment sounds intuitively true beyond question... I’m just trying to follow the arguments put forth in the paper itself.)