This then being its aim, our investigation is in a sense the study of Politics.3.
Now our treatment of this science will be adequate, if it achieves that amount of precision which belongs to its subject matter. The same exactness must not be expected in all departments of philosophy alike, any more than in all the products of the arts and crafts. [2] The subjects studied by political science are Moral Nobility2 and Justice; but these conceptions involve much difference of opinion and uncertainty, so that they are sometimes believed to be mere conventions and to have no real existence in the nature of things. [3] And a similar uncertainty surrounds the conception of the Good, because it frequently occurs that good things have harmful consequences: people have before now been ruined by wealth, and in other cases courage has cost men their lives. [4] We must therefore be content if, in dealing with subjects and starting from premises thus uncertain, we succeed in presenting a broad outline of the truth: when our subjects and our premises are merely generalities, it is enough if we arrive at generally valid conclusions. Accordingly we may ask the student also to accept the various views we put forward in the same spirit; for it is the mark of an educated mind to expect that amount of exactness in each kind which the nature of the particular subject admits. It is equally unreasonable to accept merely probable conclusions from a mathematician and to demand strict demonstration from an orator. [5]
Again, each man judges correctly those matters with which he is acquainted; it is of these that he is a competent critic.