Aristotle joins Plato in criticizing contemporary manuals of rhetoric. But how does he manage to distinguish his own project from the criticized manuals? The general idea seems to be this: Previous theorists of rhetoric gave most of their attention to methods outside the subject; they taught how to slander, how to arouse emotions in the audience, or how to distract the attention of the hearers from the subject. This style of rhetoric promotes a situation in which juries and assemblies no longer form rational judgments about the given issues, but surrender to the litigants. Aristotelian rhetoric is different in this respect: it is centered on the rhetorical kind of proof, the enthymeme (see below §6 ), which is called the most important means of persuasion. Since people are most strongly convinced when they suppose that something has been proven ( Rhet. , 1355a5f.), there is no need for the orator to confuse or distract the audience by the use of emotional appeals, etc. In Aristotle's view an orator will be even more successful when he just picks up the convincing aspects of a given issue, thereby using commonly-held opinions as premises. Since people have a natural disposition for the true ( Rhet. , 1355a15f.) and every man has some contribution to make to the truth ( Eudemian Ethics , 1216b31,) there is no unbridgeable gap between the commonly-held opinions and what is true. This alleged affinity between the true and the persuasive justifies Aristotle's project of a rhetoric that essentially relies on the persuasiveness of pertinent argumentation; and it is just this argumentative character of Aristotelian rhetoric that explains the close affinity between rhetoric and dialectic (see above §3 ).
Third, Aristotle distinguishes between practical and theoretical knowledge in terms of the level of precision that can be attained when studying them. Political and moral knowledge does not have the same degree of precision or certainty as mathematics. Aristotle says at Ethics 1094b14: "Problems of what is noble and just, which politics examines, present so much variety and irregularity that some people believe that they exist only by convention and not by nature….Therefore, in a discussion of such subjects, which has to start with a basis of this kind, we must be satisfied to indicate the truth with a rough and general sketch: when the subject and the basis of a discussion consist of matters that hold good only as a general rule, but not always, the conclusions reached must be of the same order." Aristotle does not believe that the noble and the just exist only by convention, any more than, say, the principles of geometry do. However, the principles of geometry are fixed and unchanging. The definition of a point, or a line, or a plane, can be given precisely, and once this definition is known, it is fixed and unchanging for everyone. However, the definition of something like justice can only be known generally; there is no fixed and unchanging definition that will always be correct. This means that unlike philosophers such as Hobbes and Kant, Aristotle does not and in fact cannot give us a fixed set of rules to be followed when ethical and political decisions must be made. Instead he tries to make his students the kind of men who, when confronted with any particular ethical or political decision, will know the correct thing to do, will understand why it is the correct choice, and will choose to do it for that reason. Such a man will know the general rules to be followed, but will also know when and why to deviate from those rules. (I will use "man" and "men" when referring to citizens so that the reader keeps in mind that Aristotle, and the Greeks generally, excluded women from political part icipation. In fact it is not until the mid-19th century that organized attempts to gain the right to vote for women really get underway, and even today in the 21st century there are still many countries which deny women the right to vote or participate in political life).
The Poetics is Aristotle's attempt to explain the basic problems of art. He both defines art and offers criteria for determining the quality of a given artwork. The Poetics stands in opposition to the theory of art propounded by Aristotle's teacher, Plato. In his Republic , Plato argues that "poetry is a representation of mere appearances and is thus misleading and morally suspect" (Critical, 1). In the poetics, Aristotle, Plato's student, attempts to refute his teacher by exploring what unites all poetry: its imitative nature and its ability to bring an audience into its specific plot while preserving a unity of purpose and theme. The tone of the Poetics reflects its argumentative spirit as Aristotle attempts both to explain the "anatomy" of poetry and to justify its value to human society.