If this is correct, then Aristotle's arguments for the philosophic life as the only truly good life, set apart from and above the moral life, might be seen as an exercise in rhetoric for those of his readers who are Platonic philosophers. Aristotle indicates in the Politics (1267a1-13) that for those who desire a life of pure pleasure unmixed with pain that can be enjoyed without dependence on other people, philosophy is the best remedy. For such people, describing philosophic contemplation as a godlike, self-contained activity might be the best rhetorical strategy.
In Aristotle's Rhetoric, he emphasizes that the successful rhetorician must respect the opinions of his audience. Particularly, in epideictic rhetoric of praise and blame, he explains:
"It is necessary to consider in whose presence we praise; for, as Socrates said, it is not difficult to praise Athenians among Athenians. We must also speak of what is honored by the particular audience as actually existing there, such as among Scythians, Lacedaemonians, or philosophers. And generally what is honored is to be referred to the noble, since they seem to border upon one another" (1367b7-12).This remark occurs in the context of Aristotle's claim that the rhetorician must praise what appears noble to the audience, and the audience tends to assume that what they honor is truly noble. The problem is that different audiences honor different things and therefore have different conceptions of the noble. The rhetorician must respect those differences. Furthermore, Aristotle indicates that philosophers constitute a distinct audience in that they have their own standards of honor and nobility. It seems likely, therefore, that when Aristotle, in the Ethics, praises the activity of solitary philosophic contemplation as the most honorable and noblest activity (1141a20, 1141b3, 1177a16, 1178a2), he is making a rhetorical appeal to the Platonic philosophers among his readers. It is not difficult to praise philosophers among philosophers.
The common opinion of philosophers, Aristotle indicates, is that the philosophic life is godlike because it consists in the contemplation of objects that are unchangeable and eternal. For Plato, the unchangeable and eternal objects of philosophy are the Ideas. Aristotle rejects the doctrine of the Ideas, particularly as applied to the study of the human good. The Idea of the Good, Aristotle argues in the Ethics, "is no more good by being eternal, just as a white thing that exists for a long time is not whiter than a white thing that exists for a day" (1096b3-4).
More common than Plato's doctrine of the Ideas, Aristotle suggests in the Ethics, is the belief that the unchangeable and eternal objects of philosophic contemplation are the heavenly bodies--the Sun, the Moon, and the stars. It is commonly thought that the life of wisdom is completely lacking in prudence, because while the prudent man studies the changeable and contingent affairs of human life, the wise man studies the unchangeable and eternal bodies of the cosmos (1141a30-41b2).
Although Aristotle speculates in some of his writings on the nature of the heavenly bodies, he concedes that such speculations are largely matters of "faith" (pistis) that depend on traditional myths handed down from the earliest times, and therefore such matters cannot be settled by demonstrative reasoning (Topics, 104b1-18; On the Heavens, 270b1-26, 279b4-12, 283a30-84b5, 291b24-92a10; Metaphysics, 1074b1-14). Consequently, Moses Maimonides could claim that Aristotle's arguments for the eternity of the cosmos were rhetorical rather than demonstrative (The Guide of the Perplexed, II, 13-15).
In contrast to the common view that the highest activity of philosophy is the cosmological study of the unchanging and immortal bodies of the heavens, a large part of Aristotle's philosophical writings is devoted to the biological study of the contingent and mortal bodies of living organisms. At the beginning of his Parts of Animals, Aristotle defends the philosophical dignity of his biological studies:
"Of substances that are composed by nature, some are ungenerable and indestructible throughout eternity, while others partake of generation and destruction. The former are honorable and divine but less subject to investigation by man (for there is little evidence from sensation that we can use to make inquiries about those things that we aspire to understand); but concerning plants and animals, which are destructible, there is much more information to use for knowledge, because they are all around us. . . . The knowledge of terrestrial things exceeds that of divine substances because of its greater accuracy and scope, and our knowledge of terrestrial things has the advantage that they are nearer to us and more akin to our nature. . . . Even in the case of those animals that do not delight our senses, nevertheless the nature that designed them gives inconceivable pleasures to those of us who are by nature philosophers and are able to gain theoretical knowledge of causes" (644b22-45a11).Aristotle's defense of biology as a philosophical science is important for our reading of his Ethics and Politics, because this should lead us to consider the possibility that for Aristotle ethics and politics are biological sciences. Aristotle's biological study of human beings affirms the psychophysical unity of their nature, in which mind and body are separable in speech but inseparable in reality. And so for the philosophic life to be a human life, it must be a rational life of embodied intellect, a social life of friends who live together by talking and thinking together, and thus a moral life based on mutuality and reciprocity.
Furthermore, recognizing the biological character of Aristotle's philosophizing should make us wonder whether modern Darwinian biology can sustain Aristotle's biological naturalism.