According to Schopenhauer, such usage of “dialectic” and “logic” has lasted through the medieval period to the modern times. He credits Immanuel Kant for using the word “dialectic” in a bad sense for the first time. Here’s an excerpt from “The Art of Controversy,” (Translation by: T. Bailey Saunders):
But more recently, and in particular by Kant, Dialectic has often been employed in a bad sense, as meaning “the art of sophistical controversy”; and hence Logic has been preferred, as of the two the more innocent designation. Nevertheless, both originally meant the same thing; and in the last few years they have again been recognizes as synonymous.Here’s another excerpt in which Schopenhauer is describing Aristotle’s usage of “dialectic,” “logic,” and other related terms:
According to Diogenes Laertius, v., 28, Aristotle put Rhetoric and Dialectic together, as aiming at persuasion, [Greek: to pithanon]; and Analytic and Philosophy as aiming at truth. Aristotle does, indeed, distinguish between (1) Logic, or Analytic, as the theory or method of arriving at true or apodeictic conclusions; and (2) Dialectic as the method of arriving at conclusions that are accepted or pass current as true, [Greek: endoxa] probabilia; conclusions in regard to which it is not taken for granted that they are false, and also not taken for granted that they are true in themselves, since that is not the point. What is this but the art of being in the right, whether one has any reason for being so or not, in other words, the art of attaining the appearance of truth, regardless of its substance? That is, then, as I put it above.
Aristotle divides all conclusions into logical and dialectical, in the manner described, and then into eristical. (3) Eristic is the method by which the form of the conclusion is correct, but the premisses, the materials from which it is drawn, are not true, but only appear to be true. Finally (4) Sophistic is the method in which the form of the conclusion is false, although it seems correct. These three last properly belong to the art of Controversial Dialectic, as they have no objective truth in view, but only the appearance of it, and pay no regard to truth itself; that is to say, they aim at victory. Aristotle’s book on Sophistic Conclusions was edited apart from the others, and at a later date. It was the last book of his Dialectic.