The Volokh Conspiracy
Mostly law professors | Sometimes contrarian | Often libertarian | Always independent
Aristotle and later Cicero wrote about argument being composed of logos, ethos and pathos. Most people know the "logos" as logic and "pathos" as emotion (easy to remember because of words such as "pathetic" and especially "pathos"). But it's easy to misremember "ethos" as an appeal to ethics, or to (say) the ethos of an era or a law.
But ethos actually means something different: It's an appeal to the audience's perception of the speaker's character, or (especially in Cicero's view) the character of the person whom the speaker represents. This perception can stem from the speaker's reputation, but also the speaker's manner on the present occasion:
People's minds are won over by a man's prestige, his accomplishments, and the reputation he has acquired by his way of life. Such things are easier to embellish if present than to fabricate if totally lacking, but at any rate, their effect is enhanced by a gentle tone of voice on the part of the orator, an expression on his face intimating restraint, and kindliness in the use of his words, and if you press some point rather vigorously, by seeming to act against your inclination, because you are forced to do so.
Indications of flexibility, on the part of the orator and the client, are also quite useful, as well as signs of generosity, mildness, dutifulness, gratitude, and of not being desirous or greedy. Actually, all qualities typical of people who are decent and unassuming, not severe, not obstinate, not litigious, not harsh, really win goodwill, and alienate the audience from those who do not possess them. And these same considerations must likewise be employed to ascribe the opposite qualities to our opponents. [Quoted from James M. May's translation of Cicero's De Oratore.]
To be sure, Cicero acknowledges that there are times when there is an "opportunity to use some form of sharp and violent emotional arousal to set the juror's heart aflame," and then presumably mildness has to be set aside—but Cicero's general view is that an ethos-based argument should take advantage of the virtues (real or perceived) outlined in the block quote above.
Of course, in our legal system an overt appeal to this ethos might itself be unethical (as my colleague Steve Yeazell has pointed out): A lawyer, for instance, is often barred from personally vouching for his client's innocence or other qualities of character. And of course both judges and jurors are supposed to attend to the merits of the case, not the personal qualities of the lawyers.
But human nature being what it is, listeners and readers—I'm most familiar with judges as listeners, but I suspect this is true of jurors as well—can't help but be affected by the ethos component of a lawyer's manner, personality and (especially for judges) reputation. Advice from the ancients that is worth remembering even today, just not under the obvious mental translation as "ethics."