---
title: "Agreement as evidence"
subtitle: "Conversation language and argument · Alcibiades I"
author: "Lexicon · Diotimos Editions"
date: "2026"
lang: en-US
---

*ὁμολογεῖν, homologein*, "agree"; *μὴ διαφέρεσθαι, mē diapheresthai*, "do not disagree"; *ἀμφισβητεῖν, amphisbētein*, "dispute"; *τεκμήριον, tekmērion*, "evidence"

## At a Glance

**The word.** Ὁμολογεῖν is agreeing, literally saying the same thing; διαφέρεσθαι is disagreeing; a τεκμήριον is a piece of evidence from which a conclusion is drawn.

**In *Alcibiades I*.** At 111a–b Alcibiades grants Socrates two requirements: those who are to teach must first know, and those who know agree with one another and do not disagree. The many's failure to agree then counts as evidence that they do not know and are poor teachers (111d–e), and their violent disagreement about the just shows that they cannot teach it (112a–d). A second sign of knowledge, the power to make another know, is also called evidence (118d). Agreement in argument binds the one who answers (113b), but can be withdrawn (133d).

**In this edition.** Each word has its own English: "agree" for ὁμολογεῖν, "disagree" for διαφέρεσθαι, "dispute" for ἀμφισβητεῖν, "evidence" for τεκμήριον and "concord" for ὁμόνοια.

**A place to read.** 110e–112d, where agreement and disagreement test the competence of the many as teachers.

## Meaning

Ὁμολογεῖν (*homologein*) is made of ὁμός, "same", and λόγος, "word": to say the same thing as another, and so to agree, to admit, to concede. Διαφέρεσθαι (*diapheresthai*), the middle of διαφέρειν, "to carry apart", is to be carried apart from another: to be at odds, to disagree. A τεκμήριον (*tekmērion*), a common word in the orators and the historians, is a sign or proof from which something else is concluded.

Agreement can be between persons, or within one man, as his consistency with himself: the many agree about Greek with one another and with themselves (111c), and about the just Socrates asks whether they agree "with themselves, or with one another" (112a). In the teaching argument agreement counts toward competence and disagreement against it, and twice Socrates speaks of the failure to agree as evidence (111d, 111e). This use, agreement as evidence, should be kept apart from two neighbouring ideas: ὁμόνοια, concord, the like-mindedness that Alcibiades takes the friendship of citizens to be; and the partners' assent to a step of the argument, which records what has been granted and can be withdrawn.

## Use in the book

Asked from whom he learned what is just, Alcibiades answers, "From the many" (110e), and gives as an instance his learning to speak Greek (111a). Socrates allows that of Greek "the many are good teachers", because "in that matter they have what good teachers ought to have", and he names what that is in two questions: "Don't you know that those who are to teach anything must first know it themselves?" and "And that those who know agree with one another and do not disagree?" (111a–b). Alcibiades grants both, and grants that men do not know what they disagree about, and so cannot teach it (111b). On Greek the many pass. Socrates asks whether they do not "agree on the same things, and reach for the same things whenever they want to take up a stone or a piece of wood", and whether on such matters "they agree both with one another and with themselves in private, and in public the cities do not dispute with one another" (111b–c), and Alcibiades agrees. Their agreement shows in what they do as well as in what they say.

The many fail as soon as the question is no longer what sort of thing something is, but which of its kind are fast or healthy. They cannot teach which men and horses "are good runners and which are not", and Socrates asks, "And is it evidence enough for you that they do not know, nor are they useful teachers of these things, since they agree among themselves about them not at all?" "For me, yes," Alcibiades answers (111d–e). About health Socrates asks the same: "And would it be evidence to you that they are poor teachers of this, if you saw them disagreeing?" Again Alcibiades says yes (111e). Asked whether about just and unjust men and actions the many agree with themselves or with one another, he answers, "Least of all, by Zeus, Socrates"; asked whether they disagree about them most of all, "By far" (112a). Socrates then measures this disagreement by what it leads to. He does not suppose that Alcibiades has ever seen or heard of men disagreeing about what is healthy so violently "that they fight and kill one another over it" (112a). But he asks whether the *Iliad* and the *Odyssey* are not poems "about a disagreement over what is just and unjust". Over that disagreement came "the battles and the deaths" of Achaeans and Trojans, and of Penelope's suitors and Odysseus (112b), and of those who died at Tanagra and later at Coronea, where, Socrates reminds him, Alcibiades' own father "also met his end" (112c). Asked whether such people know about the things over which they "disagree so violently that, disputing with one another, they do the worst to one another", Alcibiades answers, "It doesn't appear so, no" (112d). "So it is to teachers like these that you refer it," Socrates asks, "whom you yourself agree do not know?" "So it seems," says Alcibiades; and Socrates presses him: "How, then, is it likely that you know what is just and unjust, on which you wander so, and appear neither to have learned them from anyone nor to have discovered them yourself?" (112d).

The argument is not that whatever a majority agrees on is true. Both times it speaks of evidence (111d, 111e), it runs from disagreement to ignorance or poor teaching, and that inference holds: if those who know agree with one another, then where men disagree they cannot all know. Only once does it run the other way, from agreement to competence: from the many's agreement about stone, wood and Greek Socrates concludes, "Then it is reasonable that of these things, at any rate, they should also be good teachers" (111c). He does not call that agreement evidence, and rightly so. The premise was that those who know agree; that those who agree know is its converse, and does not follow from it. What supports the many's competence in Greek is their coordinated use, not a count of votes. Nor does a conflict show which side is right; it shows only that the many, taken all together, cannot be relied on as teachers of the just.

A few pages later the dialogue offers a second outward sign of knowledge, and calls it evidence too. The man who taught Alcibiades his letters was wise in them himself and made him so, and Socrates draws the rule: "For this, surely, is fine evidence that those who know anything do know it: when they are able to turn out another who knows it as well" (118d). Pericles, who Alcibiades says kept company with many wise men (118c), fails it. Asked whom Pericles made wise, Alcibiades can only object, "What if Pericles' two sons turned out simpletons, Socrates?"; his own brother Cleinias he calls "a madman" (118e); and he can name no one, Athenian or foreigner, slave or free, who became wiser through Pericles' company (119a). The many fail the test of agreement and Pericles the test of teaching. Each test can be read as looking for knowledge in what the claimants say and do, not in their claim to know.

The difference between agreement and concord matters in the argument about friendship (126c–127d; see Concord). Alcibiades takes the friendship that makes a city better to be concord, and grants that cities and men are in concord about numbers through arithmetic and about lengths through measurement (126c–d). Concord here rests on shared knowledge, and can be read as the counterpart of the agreement of those who know at 111b; but carried into the household, the same principle creates a difficulty instead of solving it. A husband cannot be "in concord with his wife about wool-working, when he does not know it and she does" (126e), and if friendship is concord there is no friendship where each does his own business, though that is just (127a–c). Alcibiades is left saying, "I don't even know myself what I am saying" (127d). The agreement that showed the many to know Greek cannot be had among citizens who each know a different craft, and the dialogue leaves the difficulty open.

Alcibiades' own assent has already been turned against him at 112d, and this is agreement's other role in the dialogue: it records commitments from which conclusions are drawn. When there is question and answer, Alcibiades concedes, the one saying a thing is "the one answering" (113a), and so he must own the conclusion that he does not know what is just: "I do appear to be the one, Socrates, from what has been agreed" (113b). Socrates caps it with Phaedra's words to her nurse in Euripides' *Hippolytus* (352): "you have heard this, it seems, from yourself, not from me" (113c). Such agreements can also be corrected. At 131a Alcibiades grants that whoever knows something about the body "knows what is his own, but not himself", and that the farmers and the other craftsmen know "things still further off than what is their own" (131a–b). At 133d Socrates withdraws both concessions: "we were not quite right when we agreed a moment ago that there are some who do not know themselves but know what is their own, and others who know what belongs to what is their own", for "it is for one man and one craft to discern all these" (133d–e). Agreement is a working basis for inquiry, not a guarantee beyond revision.

## Places to read

The chief passages, in the order of the dialogue.

::: {.places custom-style="Places"}
**110e–112d** The many proposed as teachers of the just and tested by agreement and disagreement: the two requirements (111a–b), agreement about stone, wood and Greek (111b–c), the failure to agree as evidence (111d–e), wars and deaths over the just (112a–d).

**112e–113c** The one answering is the one saying, and so, "from what has been agreed", it is Alcibiades, not Socrates, who has said that he does not know what is just.

**118c–119a** Making another know is "fine evidence" of knowledge, and Pericles fails the test.

**126c–127d** Concord, explained by shared knowledge, is tested in the city and the household.

**131a–b** The concession that craftsmen know what is their own, or things further off still, without knowing themselves.

**133c–e** Knowing oneself, "we agreed", is temperance; the concession of 131a–b is withdrawn.
:::

## Elsewhere in Plato

Plato draws the same line in other dialogues. In the *Euthyphro* a disagreement about number is settled by counting, about larger and smaller by measuring, about heavier and lighter by weighing; the disagreements that make men enemies and angry with one another, when they cannot come to an adequate judgment of them, are about the just and the unjust, the fine and the shameful, the good and the bad (7b–d). Number, length and weight are the three things about which the *Alcibiades I* finds cities and men in concord (126c–d). In the *Phaedrus* Socrates puts it in the language of concord and faction: about some things we are of one mind, about others in faction. At the word "iron" or "silver" we all think of the same thing, but at "just" or "good" each of us is carried a different way, and we dispute with one another and with ourselves; it is where we wander, Phaedrus answers, that we are more easily deceived and rhetoric has more power (263a–b). The verbs are the ones the *Alcibiades I* uses for disputing (111c, 112d) and for Alcibiades' wandering about the just (112d).

The *Gorgias* goes further than the *Alcibiades I*, and makes agreement a test of truth, though the agreement of one qualified partner, not of the many. Socrates would sooner have his lyre or his chorus out of tune, and most men disagree with him, than be out of tune with himself and contradict himself (482b–c). Callicles is to be his touchstone, the stone on which gold is tested: whatever Callicles agrees to about what Socrates' soul believes will be the truth itself, and their agreement "will at last have reached the goal of truth" (486d–487e). The test of teaching recurs in the *Protagoras*, where Socrates says that Pericles had his sons taught well in what teachers could teach, but in his own wisdom neither taught them himself nor handed them to another; and that he took Cleinias, Alcibiades' younger brother, away from him for fear he would be corrupted, placed him in the house of Pericles' brother Ariphron to be educated, and gave him back within six months, not knowing what to do with him (319e–320b).

## The Platonists

Olympiodorus, lecturing on this passage at Alexandria in the sixth century AD, held that those who know agree with one another, so that failure to agree is the mark of ignorance; but agreement does not prove knowledge, since the followers of Democritus all agree that there is a void, and are wrong.[^agreement-as-evidence-1]

## Later readings

The Sceptics, the philosophers who suspended judgment on every question, turned the argument from disagreement into a method. The first of the five modes of suspending judgment, which Sextus Empiricus, the Sceptic writer of the second century AD, gives as those of the later Sceptics and Diogenes Laertius ascribes to Agrippa and his followers, is the mode from disagreement, *diaphōnia*. On any question put forward, both ordinary life and the philosophers are found in a dispute that cannot be decided, and so judgment is suspended.[^agreement-as-evidence-2] The *Alcibiades I* draws a narrower conclusion from disagreement: not that judgment must be suspended, but that those who disagree cannot be teachers.

## Translation in this edition

The edition keeps "agree" for ὁμολογεῖν, "disagree" and "disagreement" for διαφέρεσθαι and διαφορά, "dispute" for ἀμφισβητεῖν, "evidence" for τεκμήριον and "concord" for ὁμόνοια. Keeping "concord" for ὁμόνοια separates the agreement that is evidence of knowledge from the like-mindedness by which Alcibiades defines civic friendship. "Agree" itself serves, as ὁμολογεῖν does in the Greek, both for the agreement of those who know (111b) and for the assent of partners in an argument (113b, 133c–d), and the context tells them apart. The one exception is 109c, where ὁμολογεῖν is "admit". The phrase ἱκανὸν τεκμήριον is "evidence enough" (111d), and καλὸν τεκμήριον "fine evidence" (118d).

## ἀμφισβητέω

Attested: ἀμφισβητοῦσιν (*amphisbētousin*; 111c), ἀμφισβητοῦντες (*amphisbētountes*; 112d), ἀμφισβητήσειε (*amphisbētēseie*; 122d). To dispute or contest, to put forward a rival claim. Socrates asks whether on stone, wood and Greek the cities "do not dispute with one another, some saying one thing and some another" (111c); over the just, men do the worst to one another, "disputing with one another" (112d). The verb marks the line between what the many can teach and what they cannot. At 122d the sense is a rivalry of wealth: in the extent and excellence of their land "not one of our people here could dispute with" the Spartans. Lemma: ἀμφισβητέω.

## διαφέρομαι

Attested: διαφέρεσθαι (*diapheresthai*; 111b twice, 112a), διαφέρωνται (*diapherōntai*; 111b), διαφερομένους (*diapheromenous*; 111e, 112a), διαφέρονται (*diapherontai*; 112d); the noun διαφορᾶς, διαφοράν (*diaphoras*, *diaphoran*; 112b) and διαφορά (*diaphora*; 112c), "disagreement". To disagree about something. In this passage disagreement tells against the competence of those proposed as teachers: Alcibiades grants that those who know "agree with one another and do not disagree" (111b). The active διαφέρειν, "make a difference" or "differ" (as at 109b and 124c), is another use and is not listed. Lemma: διαφέρομαι.

## τεκμήριον

Attested: τεκμήριον (*tekmērion*; 111d, 111e, 113e, 118d). Evidence: a sign or proof from which something else is concluded. Twice it makes the failure to agree count against the many as teachers: their failure to agree about good runners is evidence that they do not know (111d), and their disagreeing about health would be evidence that they are poor teachers of it (111e). Once it comes in a joke of Socrates', who says that Alcibiades wants new proofs "as though the earlier ones were, so to speak, little garments worn threadbare", and will not put them on again unless someone brings him "evidence clean and unsoiled" (113e–114a). And once it names the second sign of knowledge, the ability to make another know (118d). Aristotle later defined the τεκμήριον as the sign that proves by necessity, as against what is merely likely (τὸ εἰκός), and connected the word with τέκμαρ, in the old language a limit or end, because people think they bring a τεκμήριον when what they say cannot be refuted, as though the matter had been shown and brought to an end.[^agreement-as-evidence-3] Lemma: τεκμήριον.

## See also

Admission; Concord; Knowledge of one's own and others; Language; Teachers.

[^agreement-as-evidence-1]: Olympiodorus, *Commentary on the First Alcibiades* 92.4–9 (Westerink), in the lecture on 110d–112d; see F. Renaud, "The Elenctic Strategies of Socrates: The *Alcibiades I* and the Commentary of Olympiodorus", in D. A. Layne and H. Tarrant (eds.), *The Neoplatonic Socrates* (Philadelphia, 2014), 118–26.
[^agreement-as-evidence-2]: Sextus Empiricus, *Outlines of Pyrrhonism* 1.164–165; Diogenes Laertius, *Lives of the Philosophers* 9.88.
[^agreement-as-evidence-3]: Aristotle, *Rhetoric* 1.2.15–17, 1357a34–b10.