The reaction of the Socratic school against the Sophistic may serve to illustrate the third stage of thinking. This movement was not interested in the _de facto_ shaking of received ideas and a discrediting of all thinking. It was concerned rather with the virtual appeal to a common denominator involved in bringing different ideas into relation with one another. In their comparison and mutual modification it saw evidence of the operation of a standard permanent meaning passing judgment upon their conflict, and revealing a common principle and standard of reference. It dealt not with the shaking and dissolution, but with a comprehensive permanent Idea finally to emerge. Controversy and discussion among different individuals may result in extending doubt, manifesting the incoherency of accepted ideas, and so throwing an individual into an attitude of distrust. But it also involves an appeal to a single thought to be accepted by both parties, thus putting an end to the dispute. This appeal to a higher court, this possibility of attaining a total and abiding intellectual object, which should bring into relief the agreeing elements in contending thoughts, and banish the incompatible factors, animated the Socratic search for the concept, the elaboration of the Platonic hierarchy of Ideas in which the higher substantiate the lower, and the Aristotelian exposition of the systematized methods by which general truths may be employed to prove propositions otherwise doubtful. At least, this historic development will serve to illustrate what is involved in the transition from the second to the third stage; the transformation of discussion into reasoning, of subjective reflection into method of proof. Discussion, whether with ourselves or others, goes on by suggestion of clues, as the uppermost object of interest opens a way here or there. It is discursive and haphazard. This gives it the devious tendency indicated in Plato's remark that it needs to be tied to the post of reason. It needs, that is, to have the ground or basis of its various component statements brought to consciousness in such a way as to define the exact value of each. The Socratic contention is the need of compelling the common denominator, the common subject, underlying the diversity of views to exhibit itself. It alone gives a sure standard by which the claims of all assertions may be measured. Until this need is met, discussion is a self-deceiving play with unjudged, unexamined matters, which, confused and shifting, impose themselves upon us.