Aristotle's Topics is explicitly concerned with formalizing the first set of rules for disputations and the label, "dialectician" is ascribed almost exclusively to competitors in mental gymnastics. However, a close reading of the text discloses how carefully Aristotle distinguishes between the spirit of competition and the spirit of inquiry; between argument for the sake of learning and argument for the sake of intellectual exercise. Aristotle’s final exhortation to the would-be disputant indicates a higher concern than mere competition: "Moreover, as contributing to knowledge and to philosophic wisdom the power of discerning and holding in one view the results of either of two hypotheses is no mean instrument; for it only remains to make a right choice of one of them." Aristotle maintains the distinction between dialectical disputation and dialectical inquiry throughout his Topics.
Dialectic should be understood also as "A process of criticism wherein lies the path to the principles of all inquiries." Dialectical reasoning occupies a cardinal office in the Aristotelian taxonomy. The practice of dialectical disputation is indeed concerned largely with discovering arguments, but dialectical reasoning, dialectic in the broader sense, is a process of criticism and a way of securing the proof of propositions that are in doubt.
Dialectic is exemplified in the Socratic method. As one reflects on the Platonic dialogues, two things become clear: (1) Socrates engaged seriously in philosophical inquiry. Although his habit eventually got the best of him, truth-seeking was not a game for Socrates. (2) The method of Socrates is intelligible though not explicit. Stripped to its barest instrumentality, the Socratic method may be reduced to, first, beginning with a proposition, then pushing it to its conclusion by question and answer, and, finally, applying the law of contradiction. The law of contradiction is what I. A. Richards calls a ìrule of mindî and is first observed in Aristotle's Metaphysics,1011b when he writes, "The most undisputable of all beliefs is that contradictory statements are not at the same time true." The law of contradiction is a statement about the manner in which the mind operates in the meaning-making process and it is at the operational core of dialectical reasoning.
The above analysis captures the sense in which dialectic can be understood as a process of criticism or, more specifically, as a test for truth, founded on the law of contradiction. Given this context, consider the following passage:
The means whereby we are to become well supplied with reason-ings are four: (1) the securing of propositions; (2) the power to distinguish in how many senses a particular expression is used; (3) the discovery of the differences of things; (4) the investigation of likeness.
Number one above says "the securing of propositions." If any single function captures the essence of dialectic as a test for truth, it is the securing of propositions. Propositions are not secured during the course of disputation; that is a matter of reasoning which should take place prior to argument. A proposition is dialectically secured when it passes the muster of the "most undisputable of all beliefs": the law of contradiction. Therefore, securing propositions is dialectic reduced to its purest function. But what about dialectic in its essence?
A profitable way to grasp the essence of dialectic is to understand it in relation to demonstrative reasoning. In the Topics, Aristotle refers to deduction simply as "Reasoning." Induction, on the other hand, is ascribed the same name customarily associated with it: "induction." Deduction works by means of mediate inference. Aristotle identifies four types of inference, which help illuminate the broad scope of dialectical reasoning. Aristotle's four types of inference are: (1) the philosopheme which is a demonstrative inference, (2) the epichireme which is a dialectical inference, (3) the sophism which is a contentious inference, and (4) the aporeme which is an inference that reasons dialectically to a contradiction. Note how Aristotle’s four classifications of inference imply that reasoning other than demonstrative is either dialectical or contentious. Although Aristotle identifies four types of inference there are only two modes of inference: demonstrative and dialectical. The former is causal reasoning; the latter is non-causal (or contingent) reasoning.
Now reasoning is prior to disputation. Disputation requires two competitors; reasoning can, and most often does, take place in the mind of the individual. Dialectical reasoning (as a mode of inquiry rather than as a method of disputation) operates in both instances because, in the final analysis, the human mind works by philosopheme and epichireme. No wonder dialectic is so elusive; in its essence, it is a nearly unintelligible concept--cloaked in the mystery of meaning-making. The manner in which human beings intuit is the end of the intellectual road.