It is widely accepted that ruling is the sole prerogative of Plato’s philosopher-rulers because they alone possess knowledge (ἐπιστήμη). This knowledge is knowledge of the Good, taken to be the only knowledge there is in Kallipolis. Let us call this the sufficiency condition thesis (the SCT). In this paper, I challenge this consensus. I cast doubt on the adequacy of the SCT, arguing that part of the training and education of the philosopher-rulers involves their gaining practical wisdom (φρόνησις) and experience (ἐμπειρία). To succeed in this, I have two main aims. First, I argue that the philosopher-rulers must attain optimum cognitive success in these three modes of cognition to function efficiently in ruling. This involves showing that Plato, for his political project, appeals to other senses of cognitive successes besides his strictly metaphysical epistemology. Second, I attempt to demonstrate how these three modes of cognition coalesce or coincide in ruling the perceptible world, especially in the judgement and determination of concrete perceptible matters.