He also associates "phronesis" with political ability. According to Aristotle's theory of rhetoric, "phronesis" is one of the three types of appeal to character ("ethos"). The other two are respectively appeals to "arete" (virtue) and "eunoia" (goodwill). Gaining "phronesis" requires experience, according to Aristotle who wrote that:...although the young may be experts in geometry and mathematics and similar branches of knowledge ["sophoi"], we do not consider that a young man can have Prudence ["phronimos"]. The reason is that Prudence ["phronesis"] includes a knowledge of particular facts, and this is derived from experience, which a young man does not possess; for experience is the fruit of years. "Phronesis" is concerned with particulars, because it is concerned with how to act in particular situations. One can learn the principles of action, but applying them in the real world, in situations one could not have foreseen, requires experience of the world. For example, if one knows that one should be honest, one might act in certain situations in ways that cause pain and offense; knowing how to apply honesty in balance with other considerations and in specific contexts requires experience. Aristotle holds that having "phronesis" is both necessary and sufficient for being virtuous; because "phronesis" is practical, it is impossible to be both "phronetic" and akratic; i.e., prudent persons cannot act against their "better judgement." Pyrrhonism denies that the existence and value of "phronesis" has been demonstrated. The Pyrrhonist philosopher Sextus Empiricus explained the problem of "phronesis" as follows: Thus, insofar as it is up to his phronesis, the wise man does not acquire self-control, or if he does, he is the most unfortunate of all, so that the art of living has brought him no benefit but the greatest perturbation. And we have shown previously that the person who supposes that he possesses the art of living and that through it he can recognize which things are good by nature and which evil, is very much perturbed both when be has good things and when evil. It must be said, then, that if the existence of things good, bad, and indifferent is not agreed upon, and perhaps the art of life, too, is nonexistent, and that even if it should provisionally be granted to exist, it will provide no benefit to those possessing it, but on the contrary will cause them very great perturbations, the Dogmatists would seem to be idly pretentious in what is termed the "ethics" part of their so-called "philosophy".