Abstract: There has recently been much interest in the question of whether space could be derivative from some kind of non-spatial structure. But what conditions must be satisfied if the resulting space is to be, to use Tim Maudlin’s phrase, “physically salient”? Some suggest that there is an epistemic constraint to the effect that it must be “fully transparent” or “immediately intelligible” how space emerges out of the non-spatial structure. In particular, David Chalmers develops this constraint in terms of apriori entailment. But is there really an epistemic constraint like this? If so, why? What is it about something being “derivative from” something else that requires this epistemic connection between the two? I will explore an answer to this latter question, thereby defending epistemic constraints like these from some recent objections. In terms of technical difficulty, this talk rates 1/5