When one descends to rhetoric, a major category shift occurs. Not only does one give up the absolute premises of demonstration, but one also gives up the careful and rigorous syllogistic method, replacing it with enthymeme. Without the shift from syllogism to enthymeme, no such thing as rhetoric would exist in Aristotelianism because syllogism conducted on the basis of general opinion is dialectic. (Ryan 1984) Any true science must develop its own premises and methods; otherwise it cannot build a knowledge base or a set of procedures that are teachable, learnable, and productive. Dialectic can never do this because it operates in the temporal, mutable arena of opinion.
The scientist, Aristotle explains, "must deal with propositions from the point of view of truth, but for purposes of dialectic, with a view to opinion" (Ryan 1984). Equally as compromising, the dialectician, unlike the scientist, must consider how the interlocutor will respond; thus, the opinion-based response of the opponent colors the progress of an inquiry. "Dialectic," Aristotle explains, "treats as an exercise what philosophy tries to understand" (Ryan 1984). Dialectic, as the scientific method based on accepted opinion, occupies the space in the Aristotelian field nearest demonstration, preempting any other pretenders to scientific thought. In its own way, dialectic is as important as demonstration. Just as demonstration is useful in the study of the immutable, dialectic is useful in the study of the mutable.
Since everyone agrees with Aristotle that human matters are variable and that human situations do not often admit of absolute points of departure, some way of studying and deciding about the uncertain and the unstable must be found. This way, when properly done by the intellectually gifted who are well trained, is dialectic. In both the ancient Athenian Academy and the modern university, the dialectical method has been adopted by what the French call the "human sciences" and what people in America tend to call the humanities. (Ryan 1984) If the pure sciences operate in a discourse arena much like demonstration, the humanities operate in a discourse arena much like dialectic. Historians and literary critics, for example, rarely pretend to depart from absolute premises or to approach the silence of absolute knowledge, but they do pretend to a rigor equal to that in the sciences. Humanities students must learn to "demonstrate" in acceptable discourse what they think and why they think it, and they must learn how to anticipate and respond to the objections of others on similar dialectical quests.
Aristotle makes the hierarchy clear. "We must now observe that not only dialectical and demonstrative syllogisms are effected by means of the figures already described," he explains, "but also rhetorical syllogisms and in general every kind of mental conviction, whatever form it may take" (Gaines 1996). Aristotle explains that rhetorical arguments operate in the same way as demonstrative and dialectical arguments, except that they use enthymeme and example instead of induction and syllogism. And at the beginning of the Rhetoric, Aristotle explains that "when, certain things being posited, something different results by reason of them...such a conclusion in Dialectic is called a syllogism, in rhetoric an enthymeme" (Aristotle 1991).
There is a reason for this change, and Aristotle makes it unmistakably clear repeatedly in the Rhetoric. The difference, as James Berlin has rightly pointed out, is audience (Ryan 1984). The only reason anyone would ever abandon dialectic and turn to rhetoric is that the intended audience is incapable of the detail and rigor of dialectic. "The function of rhetoric," Aristotle explains quite clearly, "is to deal with things about which we deliberate, but for which we have no systematic rules; and in the presence of such hearers as are unable to take a general view of many stages, or to follow a lengthy chain of argument." (Aristotle 1991) The presumed audience for rhetoric, he says a few lines later, "is supposed to be a simple person" (Aristotle 1991).
The reason the rhetorician can resort successfully to maxims (which neither the demonstrator nor the dialectician could ever do) is the clownish, coarse, vulgar nature of a rhetorical audience. Unlike dialectic, in which the discussants can and should work through to their conclusions with as much care and detail as possible, in rhetoric, "it is impossible to ask a number of questions, owing to the hearer's weakness. Wherefore also we should compress our enthymemes as much as possible" (Ryan 1984). The audience for rhetoric is so intellectually straightened that even if we have demonstrative knowledge available, our audience will not be able to comprehend it.
"In dealing with certain persons," Aristotle explains, "even if we possessed the most accurate scientific knowledge, we should not find it easy to persuade them by the employment of such knowledge. For scientific discourse is concerned with instruction, but in the case of such persons instruction is impossible; our proofs and arguments must rest on generally accepted principles, as we said in the Topics, when speaking of converse with the multitude" (Ryan 1984).
The most damning indictment of rhetoric comes when Aristotle takes up the enthymeme near the end of Book II of the Rhetoric. He begins by repeating his explanation that an enthymeme is "a kind of syllogism"; then he continues the explanation by showing that a rhetorical argument cannot extend too far back toward original premises, "nor should it include all the steps of the argument." (Aristotle 1991) Indeed, the reason why "the ignorant" are often more persuasive in rhetorical settings than the educated is that they know better than to engage in the sort of inquiry characterized by dialectic (Aristotle 1991).
If one juxtaposes the goals of demonstration, dialectic, and rhetoric, the descent is clear. Demonstration must lead to ‘truth as opposed to lie’. (Short 1989) Demonstration has a divine quality about it in that it puts a matter outside human hands, outside the reach of opinion or persuasion. Its lure is profound, especially in the classroom where the attraction of truth, correctness, ironclad learnability, and certainty beckon with such power. Dialectic leads only to something, which researchers render as "a notion, true or false," an expectation, a mere opinion or conjecture, an imagination, a supposition, or even a fancy. (Short 1989)
Demonstrative knowledge is the sort that physics, mathematics, and the pure sciences have always sought. The truth of the inquiry lies in the thing being studied, not in the person studying it. Any hypothesis can be proved true or false -- absolutely, if the research is available. With dialectic, the location of truth moves from the object studied to the person making the study, focusing attention, in Grimaldi's words, on "an area of reality which is at a level definitely below Plato's world of forms and Aristotle's metaphysics" (Ryan 1984). The dialectician moves toward opinion, knowing all along that absolute opinion is self-contradictory, but nevertheless being as careful as possible to construct and defend true and reliable opinion. The location of dialectic is both the curse and the blessing of the traditional humanities: the curse because the humanities can never compete with the pure sciences in the creation of "knowledge" the blessing because the humanities retain the role of critical, evaluative thinking that can at least claim the right to judge the absolute results of science.
Rhetoric can never offer more than logic, and another, equally important metaphysical downshift occurs. Thus with the move to rhetoric, the location of truth changes once again, this time to the perceived believability of the speaker. In demonstration, truth exists absolutely in the thing being studied. In dialectic, truth exists within the rigor of the argument itself. In rhetoric, truth exists in the strategies necessary to persuade a simple audience. (Gaines 1996) Both Thomas Cole and Edward Schiappa have argued recently that Plato and Aristotle created the term rhetoric as a backward and backhanded way of degrading their opponents, from Isocrates back to Protagoras. "Whenever the conclusions to which philosophy leads must be made acceptable to those whose philosophical attainments are one-sided or imperfect or nonexistent," Cole explains, "or when true opinion is sought as a goal rather than the logos that is able to give account of itself, or when the likeness of truth is to be presented as a substitute for truth itself, rhetoric is necessary -- so necessary that, had it not existed already, Plato and Aristotle would surely have had to invent it," which, Cole goes on to say in the next paragraph, "they effectively did" (Ryan 1984). By the time Aristotle left Athens in 323, Schiappa continues the argument, he had completed the conceptual and terminological separation of philosophy and rhetoric (Ryan 1984).
Such a separation necessarily degrades rhetoric. Each time Aristotle sets up a hierarchical system, he puts rhetoric at the bottom, where none but the weak-minded and poorly trained ever venture. Those who are eager to argue that Aristotle conceives rhetoric as necessary should remember that he also considered slavery necessary. Within the Aristotelian system, rhetoric serves the necessary function of being the thing excluded so that knowledge can know itself by having something to be better than and different from.
As Aristotle puts together the moves that will finally enthrone philosophy as the supreme human endeavor, he separates knowledge into two kinds, theoretic and practical: "philosophy is rightly called a knowledge of Truth. The object of theoretic knowledge is truth, while that of practical knowledge is action; for even when they are investigating how a thing is so, practical men study not the eternal principle but the relative and immediate application" ().
40 Of course his hierarchy is obvious. Theoretical science is the most noble and desirable because it deals with causes and principles. And theology, the study of Being qua Being, is the Supreme Science: "The speculative sciences...are to be preferred to the other sciences, and 'theology' to the other speculative sciences" (Ryan 1984).
Aristotle complicates this grid when he turns to psychology to try to locate the place where demonstration, dialectic, and rhetoric occur. He begins by dividing the soul into its rational and irrational halves, and then he divides the rational half into two halves, "one whereby we contemplate those things whose first principles are invariable, and one whereby we contemplate those things which admit of variation." (Ryan 1984) Aristotle names the first the "Scientific Faculty", the second the "Calculative Faculty". Aristotle takes up the five ways in which the rational soul operates: art, science, prudence, wisdom, and intelligence (Ryan 1984).
It is, however, fair (and not very controversial) to argue that Aristotle goes on to repeat the tripartite division he makes in the Metaphysics by again dividing intellectual inquiry into the scientific, the productive, and the practical. As one would expect, the most elevated of the modes of inquiry is science, which studies eternal objects through demonstrative reasoning leading to certain conclusions. Beneath science come the actions of the practical and productive intellects. These two actions are different and somewhat antithetical, with neither being part of the other. As their names imply, one focuses on the product, the other on the process of doing.
The productive intellect, according to Aristotle, is art, and "art is the same thing as a rational quality, concerned with making, that reasons truly." (Garver 1986) The practical intellect, on the other hand, is not the same as Science. Nor can it be the same as Art. It is not Science, because matters of conduct admit of variation; and not Art, because doing and making are generically different.... It remains therefore that it is a truth-attaining rational quality, concerned with action in relation to things that are good and bad for human beings. (Ryan 1984) In distinguishing art from prudence, Aristotle offers a splendid example: we can speak of excellence in art but not of excellence in prudence. The self-evident reason is that one can be an artist without being an especially good artist, but one cannot be prudent without being good at prudence for a person poor in prudence is ipso facto not prudent