As Socrates recounts his search for causes (aitiai) in the Phaedo, he identifies the following as genuine causes: intelligence (nous), seeming best, choice of the best, and the forms. I argue that these causes should be understood as norms prescribing the conditions their effects must meet if those effects are to be produced. Thus, my account both explains what Socrates’ causes are and the way in which they cause what they cause.