hypothesis: the point of 3:5 is only to answer the question raised immediately before the chapter, i.e. “we must ask why the mind does not always think”. A’s answer is that mind does always think, when it is itself and nothing more. Being presently a part of a compound that is “something more”, it does not.
The hypothesis has the value of logical continuity, which is much shakier on other accounts of 3:5. A’s explanation of nous first argues for its proper nature as what is nothing actual before it operates, in contradistinction to all embodied cognition, and then talks about the operation or object of intellect as opposed to an object of embodied cognition. He then raises two objections to his idea of intellect: the first is the interaction problem and the second is how mind can think itself. A’s response to the second involves the claim that for unembodied beings the object and power are one thing, which raises the large and pressing problem of how a man could ever be not thinking, which is the problem he is trying to solve in 3.5.