Socrates had died in 399, when Plato was twenty-nine. Most of what we know of Socrates comes from Plato’s dialogues. A central Socratic tenet was that moral virtue consists in knowledge, so that one who acts wrongly or viciously acts from ignorance. The Socratic conception of happiness linked it closely with virtue and knowledge. When Socrates is condemned to death, he chooses to remain in Athens, thinking virtue to be `the most valuable human possession`.(Plato, Crito 53c7.) Plato continued the Socratic tradition, identifying moral virtue with an ordering of the soul in which reason governs the emotions and appetites to the advantage of the virtuous person. Aristotle can be seen as following the same agenda, asking the same sorts of ethical questions and using the same concepts, though he does also employ philosophical apparatus developed in other areas of his thought (e.g., the activity/process distinction put to use in his analysis of pleasure). Arguably (a word always to be assumed when an interpretation of Aristotle is asserted), two aspects of Aristotle’s ethics set him apart from Socrates and Plato: an emphasis on virtuous activity as opposed, on the one hand, to merely possessing the virtue, and, on the other, to other candidates as components of happiness, such as pleasure. For Aristotle, happiness consists in, and only in, virtuous activity.
Aristotle’s method also contrasts with those of Socrates and Plato. The Socratic method consisted in the asking of questions of the `What is X?’ variety. Definitions of virtue, justice, courage, or whatever, would then be subjected to criticism by Socrates, ending in a state of puzzlement, which is at least one step further on from false belief. Socrates’ own views are stated through indirection, embedded in his questions and his often ironic responses to proffered answers. In his earlier dialogues, Plato follows the same method vicariously, in his portrayals of the relentlessly interrogative Socrates. He later developed sophisticated and radical metaphysical and moral views, but we are still distanced from their author through his continued use of the dialogue form. One difficult question any student of ancient philosophy must face is that of the relation between the real Socrates, Socrates the character in Plato’s dialogues, and Plato himself. (ARISTOTLE, Nichomachean Ethics. Ed. and Tr. Roger Crisp. Cambridge: Cambridge University Press, 2004, p. viii-ix)