The Socratic proposition “It is better to suffer wrong than to do wrong” is not an opinion but claims to be truth, and though one may doubt that it ever had a direct political consequence, its impact upon practical conduct as an ethical precept is undeniable; only religious commandments, which are absolutely binding for the community of believers, can claim greater recognition. Does this fact not stand in clear contradiction to the generally accepted impotence of philosophical truth? And since we know from the Platonic dialogues how unpersuasive Socrates’ statement remained for friend and foe alike whenever he tried to prove it, we must ask ourselves how it could ever have obtained its high degree of validity. Obviously, this has been due to a rather unusual kind of persuasion; Socrates decided to stake his life on this truth – to set an example, not when he appeared before the Athenian tribunal but when he refused to escape the death sentence. And this teaching by example is, indeed, the only form of “persuasion” that philosophical truth is capable of without perversion or distortion; by the same token, philosophical truth can become “practical” and inspire action without violating the rules of the political realm only when it manages to become manifest in the guise of an example. This is the only chance for an ethical principle to be verified as well as validated.--Hanna Arendt (1968) "Truth in Politics," (p. 243 in Between Past and Present).
I do not understand the last sentence of the quoted passage.
In "Truth in Politics," while relying on a distinction between ethics and politics which she grafts on a Platonizing distinction between truth (which she connects with philosophy) and opinion (which she connects with politics), Arendt claims to writes from the truthful perspective outside of the "political realm" (258). [To be sure, factual truth matters to politics because it is an obstacle to lots of forms of persuasion; Arendt notes that (229) Madison (who got it from Adam Smith) teaches that government rests on opinion, but the truth can undermine it.] Her claim is a bit odd because she is manifestly instructing the public in her essay (which first appeared in the New Yorker) in order to recognize the social, if not political utility of a distinct realm in which truth rules within and protected by the polity. The agents that occupy that realm (the institution of justice, and research in the modern university) are supposed to be motivated by impartiality, love of truth, and free from "self-interest in thought and judgment." I like that phrase, but we saw recently that Arendt recognized that influence and power would corrode this ethos.
That is to say, Arendt is using a form of rhetoric, or persuasion, in the service of a kind of advocacy on behalf of the institutions that promote truth (which people think is impotent). One wonders if this kind of persuasion is also part of "the rules of the political realm," or if Arendt is cheating. Either way, given that hers is different from the less subtle, Socratic form of persuasion -- in staking his life as an exemplar of both the Socratic proposition and as evidence that, thereby (?), truth can be, well, potent in motivating action* --, we can conclude that hers does distort (at least somewhat) "philosophical truth" in the process. I suspect the distortion is the fact philosophers do not want to be (justified as) instrumental to political life (but prefer being oriented toward their a-political truth).
I mentioned above that Arendt recognizes the great significance of truth in political life, but not as a source of action. As she writes in a famous passage (she recycled it for somewhat different ends in 'Lying in Politics'):
The mere telling of facts, leads to no actions whatever; even tends under normal circumstances, toward acceptance of things as they are....Truthfulness has never been counted among the political virtues, because it has little indeed to contribute to that change of the world and of circumstances which is among the most legitimate political activities. Only when a community has embarked upon organized lying on principle, and not only with respect to particulars, can truthfulness as such, unsupported by the distorting forces of power and interest, become a political factor of the first order. Where everybody lies about everything of importance, the truthteller, whether he knows it or not, has begun to act; he, too, has engaged in political business, for, in the unlikely event that he survives, he has made a start toward changing the world. (246-7)
She seems committed to the view that reporting of the facts ordinarily entrenches a status quo bias (that's compatible as she notes with it sometimes undermining it). So most governments would have nothing to fear from (say) public exposure of their activities. As her own essay goes on to remind us, most governments -- including liberal democracies -- act otherwise and, by their cover-ups, create the scandals that undermine them suggesting, if Arendt is right, that they lack practical wisdom.
One final thought, by staking his life, Socrates acted in a way that is political. Arendt does not quite claim why this is so, but presumably this is because (one can agree this much with Hobbes) the political exists at least in part to preserve life and postpone death. Truth compels those that grasp it, but does that do not, she seems to be saying, require an exemplar of what I have called philosophical integrity' the intimate relationship (perhaps one of partial identity or accountability) between our words and our character as revealed by our habitual deeds.. And perhaps, what Arendt is saying, is that such integrity is a matter of public record, or validation.