There are two types of parrhesia which we must distinguish. First ,there is a pejorative sense of the word not very far from " chattering " and which consists in saying any or everything one has in mind without qualification. This pejorative sense occurs in Plato, for example, as a characterization of the bad democratic constitution where everyone has the right to address himself to his fellow citizens and to tell them anything -even the most stupid or dangerous things for the city. This pejorative meaning is also found more frequently in Christian literature where such " bad " parrhesia is opposed to silence as a discipline or as the requisite condition for the contemplation of God. As a verbal activity which reflects every movement of the heart and mind, parrhesia in this negative sense is obviously an obstacle to the contemplation of God.
Most of the time, however, parrhesia does not have this pejorative meaning in the classical texts, but rather a positive one. " parrhesiazesthai " means " to tell the truth. " But does the parrhesiastes say what he thinks is true, or does he say what is really true ? To my mind, the parrhesiastes says what is true because he knows that it is true ; and he knows that it is true because it is really true. The parrhesiastes is not only sincere and says what is his opinion, but his opinion is also the truth. He says what he knows to be true. The second characteristic of parrhesia, then, is that there is always an exact coincidence between belief and truth.
It would be interesting to compare Greek parrhesia with the modern (Cartesian) conception of evidence. For since Descartes, the coincidence between belief and truth is obtained in a certain (mental) evidential experience. For the Greeks, however, the coincidence between belief and truth does not take place in a (mental) experience , but in a verbal activity, namely, parrhesia. It appears that parrhesia, in his Greek sense, can no longer occur in our modern epistemological framework.
I should note that I never found any texts in ancient Greek culture where the parrhesiastes seems to have any doubts about his own possession of the truth. And indeed, that is the difference between the Cartesian problem and the Parrhesiastic attitude. For before Descartes obtains indubitable clear and distinct evidence, he is not certain that what he believes is , in fact, true. In the Greek conception of parrhesia, however, there does not seem to be a problem about the acquisition of the truth since such truth-having is guaranteed by the possession of certain moral qualities :when someone has certain moral qualities, then that is the proof that he has access to truth--and vice-versa. The " parrhesiastic game " presupposes that the parrhesiastes is someone who has the moral qualities which are required, first, to know the truth, and secondly, to convey such truth to others .
If there is a kind of " proof " of the sincerity of the parrhesiastes, it is his courage. The fact that a speaker says something dangerous -different from what the majority believes- is a strong indication that he is a parrhesiastes. If we raise the question of how we can know whether someone is a truth-teller, we raise two questions. First, how is it that we can know whether some particular individual is a truth-teller ; and secondly, how is it that the alleged parrhesiastes can be certain that what he believes is, in fact, truth. The first question - recognizing someone as a parrhesiastes - was a very important one in Greco-Roman society, and, as we shall see, was explicitly raised and discussed by Plutarch, Galen, and others. The second skeptical question, however, is a particularly modern one which, I believe, is foreign to the Greeks.