The most striking aspect of book one in Aristotle’s On Rhetoric is that we are once again presented with a new classification and purpose of Rhetoric. According to Aristotle, “Rhetoric is an antistrophos to dialectic; for both are concerned with such things as are, to a certain extent, within the knowledge of all people and belong to no separately defined science” (30). Part of the reasoning for this is because speakers often need both to reach the desired end. “A result is that all people, in some way, share in both; for all, up to a point, try both to test and uphold an argument [as in dialectic] and to defend themselves and attack [others, as in rhetoric]” (30).
Both, according to Aristotle, are also unique. Dialectic is supposed to arrive at agreed truths while rhetoric is supposed to persuade by the best means possible (meaning that truth is sometimes not a clearly defined point of an argument, which is exactly where rhetoric must step in and leads judges and juries to an apparent truth). Unlike dialectic, however, rhetoric must maintain its argument within the specific topic under argument. Additionally, dialectic requires the dialectician to maintain a single side of an issue, while a rhetorician must “be able to argue persuasively on either side of a question, just as in the use of syllogisms, not that we may actually do both (for one should not persuade what is debased) but in order that it may not escape our notice what the real state of the case is and that we ourselves may be able to refute if another person uses speech unjustly” (35). One of the strongest distinctions between rhetoric and dialectic will also return us to the idea of truth, because dialectic is about reaching truths through agreement while rhetoric is about acquiring a decision from an audience. In other words, “rhetoric, therefore, does not belong to a single defined genus of subject but is like dialectic and that it is useful is clear - and that its function [ergon] is not to persuade but to see the available means of persuasion in each case” (36).
Another layer of distinction Aristotle provides is that rhetoric is an art, unlike Socrates’ idea of rhetoric being a knack. According to Aristotle, rhetoric is concerned with demonstration or the ability to acquire the skill, arrange it into a carefully crafted argument, and then present it. “Since it is evident that artistic method is concerned with pisteis and since pisitis is a sort of demonstration […] and since rhetorical apodeixis is enthymeme […] and the enthymeme is a sort of syllogism […] it is clear that he who is best able to see from what materials, and how, a syllogism arises would also be most enthymematic - if he grasps also what sort of things are enthymeme is concerned with and what differences it has speech” (35-36).