  The passage depicts the knowledge the blind possess of the colors white and black as, what we would characterize as, propositional knowledge. Yet the text’s central claim is that the blind do not qualify as “knowing white and black,” because they are unable to identify them in practice. For the Mohists, the key criterion of knowledge is not the mere ability to make correct statements — as when the blind “use the names ‘white’ and ‘black’ in strings the same way” as the sighted — but the ability to “distinguish the things” denoted by these words (Book 19, “Condemning Aggression”).