Knowing what to do and say · Lexicon

From the book

Alcibiades II

Plato · Diotimos Editions · 2026

Orientation

At a Glance

The wordEidenai is to know; the phrase “what one must do and say” supplies the content of the practical knowledge sought.
In Alcibiades IIAt 140e Socrates proposes that the intelligent are those who know what they must do and say; the unintelligent know neither.
In this editionThe edition retains “must” in the defining phrase, keeping its normative force audible.
A place to readKnowledge of required action and speech defines the intelligent.

Meaning

Eidenai is to know; the phrase “what one must do and say” supplies the content of the practical knowledge sought. Dei marks what is required or fitting to do, not simply what one has the physical ability to accomplish. The phrase is a definition by the object of knowledge, not a new technical noun for morality.

Use in the book

At 140e Socrates proposes that the intelligent are those who know what they must do and say; the unintelligent know neither. He then says that those who lack both will unwittingly speak and act as they should not. This makes error in prayer one form of a broader failure of conduct. The inference is stated forcefully: lack of knowledge is taken to issue in misconduct, although the passage does not separately argue that ignorance must produce a wrong act on every occasion.

The intervening discussion gives the formula a more discriminating content. An orator may know how to advise without knowing whether and when advising is better, and the soldier may know war without knowing its right time and duration. Knowing “what one must do” must therefore include the practical appropriateness of deploying a skill. At 145c the knowledge of the best supplies the condition under which technical capacity can make someone a sufficient adviser.

At 150b the formulation returns, now of both intelligent and just people and explicitly toward gods and human beings. The expansion prevents religious speech from being isolated as a technical ritual accomplishment. The person who can pay for magnificent sacrifice but repeatedly makes mistakes toward gods and people does not thereby satisfy the condition. At 150d education is correspondingly described as learning how one must be disposed toward both.

Places to read

140eKnowledge of required action and speech defines the intelligent.
144e–145c2Ability to advise or act is tested against when and whether it is better.
149e–150bThe soul, justice and conduct matter more than costly ritual.
150dThe educational task becomes learning the right disposition toward gods and people.

Translation in this edition

The edition retains “must” in the defining phrase, keeping its normative force audible. Burnet brackets an intrusive ē at 150b2, and the English follows the resulting text. “Those who know” should not be expanded into a claim that every knowledgeable specialist is just.