It is impossible in this article to go thoroughly into this question at issue between experiential and rationalistic logicians. All that can be said is that as a matter of fact Aristotle's logic was merely a statement, empirically grounded, of the processes of correct thinking: and all logical advance since Aristotle's day, notably ill's addi tion of scientific induction to logic, has been secured by a careful study of the actual processes of what is generally regarded as correct thinking. That is, the science of logic in fact originated and has grown on experiential foundations. There is no a priori necessity that we should think logi cally: otherwise there would be no illogical think ing going on in the world. Neither is there any way of showing that a certain mode of thinking is incorrect except by showing that it actually leads to error. A teacher in logic who wishes to show the fallaciousness of a certain style of reasoning does not appeal to any inner con sciousness or a priori intuition of his pupil. Ile shows in the concrete, i.e. by example, that this style of reasoning issues in mistaken conclusions. For example. he shows that it is not correct to say that because a]] .7%! is P and all :\ I is S. there fore all S is P. Ilow does he prove it ? By pointing out that the correctness of the formula would involve the correctness of the argument that all ducks are fowls and all ducks are ani mals. therefore all animals are fowls. Again. it is not correct to say that because B comes after it is the effect of A. Why? Because such a formula, would justify the conclusion that cock, with lively din, scatters the rear of darK. nes. thin." Experience, however, shows that the cock and his din do not have airs perceptible influence in dispelling darkness. hence the for mula is incorrect, and reasoning according to that formula is fallacious. But there are other formulas which express the processes of correct thinking. These formulas are obtained by com paring actual trains of thought which had to valid conclusions, and by discovering their is of identity.
Now all thinking is judging and all thought is judgment (q.v.). .1 judgment can always be analyzed into subject and predicate, which in the act of are recognized a, standing to each other in the relation of object of thought and qualification of that object. Tin, .subject of a judgment is either a percept or a concept (q.v.). Of the judgments that appear earli est in thought the subjects are without doubt percepts. It is the business of psychology to in vestigate the origin of percepts. Logic accepts these percepts as given facts any question about whose origin is of no pertinence to its inquiry. inasmuch as it is merely interested in the manner in which these percepts are manipulated by thought; or, in other words, in the various changes which percepts undergo and in the vari ous relations into which they enter. when they become elements in a thought process. Nor are even all these changes undergone by percepts of direct bearing upon the problems of logic. For instance, before any judgment can be made upon a percept. attention (q.v.) is This state of attention is a very diffieult state for the psychologist to deal with ; but all the perplexities are of no immediate interest to the logician as logician. He accepts the results pro duced by attention without bothering himself with questions as to the nature and conditions of attention. Only those changes of percepts which have a direct bearing upon the validity of judgments are treated in logic. These changes are all summed up in the words analysis (q.v.) and generalization. to which may be added com parison (q.v.), inasmuch as neither analysis nor generalization occurs without comparison. In deed. analysis, comparison, and generalization aro really different aspects of the same process. It
is at first probably only as one percept is com pared with another that any analysis can be made of either of them: and this analysis is pos sible only as some attribute is discovered to be common to them. And vet this discovery of a common attribute is las.° facto an analysis of the percepts. It is usual to add that before a per cept can figure in judgment. the common attri bute predicated of it must he associated with some word or phrase. That is. many logicians claim that language is a necessary precondition of all judgment. Thus Sigwart says that is essential that this" predicate idea be taken from those of our ideas which arc already known to us and named by words which are understood. It must he an idea which has been already received into which is con nected with a word enabling us to retain and reproduce it. and which is distinguished from all other ideas. . . T catmint say is blue, this is red: unless I am already familiar with the ideas blue and red, and can reproduce them with the word. Judgment is possible only when a number of such distinct ideas arc retained and easily called into consciousness" (English translation). I;at acknowledges that "some thought is already involved in the process by which these ideas are formed." lie excludes the consideration et such tlam,..dit, from logic simply because it "precedes conscious and intentional thought." The difference then between the view advocated by Sigwart and that presented above dues not con cern the facts, hut it concerns the definition and scope of logic. if logic is the science of the con ditions of all correct thinking., then judgments whose predicates have no names 11111st lie included in its treatment.. Otherwise logic must be de fined as the science of the conditions of correct intentional thought; and such a definition un warrantably restricts the meaning of a word that for ages has had a wider denotation. Logic then should treat of the processes by which a percept is recognized as having a qualifying feature even though the thinker has as yet no names at his disposal.
Predicate ideas are, in one sense, always gen eral; in another sense they may be singular. It is at first perhaps only as one percept is com pared with another that a feature is recognized in either as qualifying it. A common feature. recognized as qualifying several percepts, is a general idea, and when it is named the term used to designate it is called a general term. But a feature may lie peculiar to one object. which at various times presents itself to obserV31.1011, and may be recognized as qualifying the object each time it appears. In such a ease the feature, recognized as characterizing the percept every time it. appears is common to the various ap pearances of the percept. but peculiar to the percept. Whether, therefore, the idea of that feature be considered general or singular de pends upon the point of view. Again. any feature which experience presents as a peculiar attribute of an object of perception may appear as a common attribute of various imaginary objects, and in this way lie a general idea. In a similar manlier, upon the point of view depends the es sential or accidental character of an attribute of an object. Every term representing a com plex of many qualities or attributes may lie used for certain of them as essential to the judg ment in which the term is employed, while others are disregarded. and accordingly, for that use, are merely accidents or chance phenomena. The accidental character is thus not inherent in the particular quality, but is determined by the selective nature of thought, and exists only for the particular usage or judgment.