Aristotle holds teleological view of biology. That is, he believes that all living things exist to fulfill some telos, or purpose. This telos is determined primarily by what makes that living thing distinctive. For instance, the telos of a plant is primarily nutritive: its goal in life is to grow. Aristotle distinguishes humans from other animals by saying that we are capable of rational thought. Because we are the distinctively rational animals, our telos must be based in our rationality.
This theme underlies a great deal of the Ethics. In discussing voluntary action, Aristotle emphasizes choice based on rational deliberation. Our actions can be morally praiseworthy or blameworthy because we are able to think about them and decide rationally on the best course of action.
Most of the Ethics is devoted to discussing the various moral virtues. In the end, however, Aristotle explains that these moral virtues are not ends in themselves so much as necessary preconditions for living a good life. This good life is based on our rational faculties, which explains his discussion of the intellectual virtues in Book VI.
Of the intellectual virtues, two of them—prudence and art—are practical virtues. These help us fulfill our practical needs and so cannot be ends in themselves. Of the intellectual virtues, wisdom is the highest, since it combines the other two virtues of scientific knowledge and intuition. Scientific knowledge and intuition help us to figure out what the world is like. Wisdom consists of the ability to contemplate the totality of experience from a place of knowledge. As such, wisdom represents the most achieved state of the rational intellect.
Because wisdom is the highest intellectual virtue, and because the rational uses of the intellect are the highest human goal, the philosophical contemplation made possible by wisdom is the supreme human achievement. While this contemplation could be called “philosophy,” we should be careful to note that for the Greeks, philosophy consists of a contemplation of knowledge generally, and not the more specialized study that modern philosophy consists of.
Is Aristotle right in saying that philosophical contemplation is the highest good? He certainly provides many compelling and noble reasons to think so, but he never provides a watertight argument for thinking so. We might feel inclined to respond that some of the lower pleasures are more worthwhile than solemn contemplation. To this, Aristotle might respond that we are giving into our less than human animalistic natures. But aside from feeling Aristotle’s stern disapprobation, there does not seem to be any compelling reason to think that a little animalistic fun is not in itself sometimes quite worthwhile.