This use of the words as synonymous terms lasted through the Middle Ages into modern times; in fact, until the present day. 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 recognised as synonymous.
It is a pity that the words have thus been used from of old, and that I am not quite at liberty to distinguish their meanings. Otherwise, I should have preferred to define Logic (from λόγος, "word" and "reason", which are inseparable) as "the science of the laws of thought, that is, of the method of reason"; and Dialectic (from διαλέγεσθαι; "to converse"—and every conversation communicates either facts or opinions, that is to say, it is historical or deliberative) as "the art of disputation," in the modern sense of the word. It is clear, then, that Logic deals with a subject of a purely a priori character, separable in definition from experience, namely, the laws of thought, the process of reason or the λόγος; the laws, that is, which reason follows when it is left to itself and not hindered, as in the case of solitary thought on the part of a rational being who is in no way misled. Dialectic, on the other hand, would treat of the intercourse between two rational beings who, because they are rational, ought to think in common, but who, as soon as they cease to agree like two clocks keeping exactly the same time, create a disputation,
