Knowing that and knowing what

Use in the book

At 167a Socrates' summary offers a robust capacity: a temperate person examines what he himself and others know, including what someone merely thinks he knows. It is important that the promised power concerns particular epistemic claims. Knowing simply that a person is knowledgeable in some respect would not settle whether his current claim to medical expertise is genuine.

Once knowledge of knowledge has been granted, Socrates asks what it could distinguish (170a). Critias agrees that its task extends only to determining which is knowledge and which is not. The fields of the healthy and the just belong instead to medicine and statesmanship. Unless a person also knows those fields, he might identify that he or another has some knowledge, but not its content (170b). Socrates introduces music and house-building as further examples (170c): he knows what is harmonious by music, what belongs to building by building. Temperance's second-order object cannot silently confer every first-order expertise.

This yields the expressly weakened reformulation at 170d: knowing that one knows and that one does not know, rather than what one knows and does not know. The text then applies it to a professed doctor. To establish that this person has medicine, one must test statements and performances concerning the healthy and diseased (171a–b). Merely recognizing some epistemic competence would not identify it as the competence claimed.

There is an interpretive difficulty within the weakened proposal itself. What exactly can it mean to know that one does not know, while not specifying anything one does not know? A charitable reading takes the passage as isolating epistemic status from a determinate field for the sake of Critias' hypothesis, not as asserting that such empty status-awareness exists. Another reading argues that separating knowledge from every content has already made the purported capacity unintelligible. The dialogue leaves possibility conceded rather than proven, so neither reading should present the weaker capacity as Plato's established psychological doctrine.

At 175b–c2 the concluding retrospect complicates rather than abolishes the distinction. Socrates says they granted access to the works of other knowledges so that a person might know, of things he knows, that he knows them, and of things he does not know, that he does not know them. He calls the latter problematic because it seems to know in some way things entirely unknown. The difference between knowing a subject matter and knowing one's ignorance of it is precisely what needs defending. It would be careless to replace this qualified puzzle with the flat contradiction “he both knows and does not know the same thing in the same respect”.

The distinction also limits an attractive contemporary paraphrase: “metacognition”. Some metacognition is about particular answers, methods or limitations and therefore includes content-specific cognition. Critias' proposed expertise is restricted to knowledge as its sole object. The argument tests the stronger abstraction, not every recognizable activity we now call metacognitive.

Places to read

1. 167a–bOriginal content-sensitive claim and statement of the two questions
2. 170a–d2Explicit separation between knowing that and knowing what
3. 170e–171c2Failure to certify expertise without its subject matter
4. 175b–c2Qualified puzzle about knowing one’s ignorance

Translation in this edition

At 167b Burnet prints the supplied words ⟨ὅτι οἶδε καὶ⟩, “that one knows it and”; the edition marks their supplementation. At 170b–c2 the first ὅτι in “what it is he knows” functions interrogatively, while nearby ὅτι clauses state that he knows. Greek accentuation and context, not an invariant English equivalent, determine the sense. At 175c the translation preserves “in some way or other” and “not at all”.

ἁμῶς (hamōs)

In some way or other; qualifies the problematic claim to know in some respect what one does not know. References: 175c. Lemma: ἁμῶς. See Knowing that and knowing what.