mistaking falsehood and even nonsense for knowledge, and yet firmly convinced of their wisdom and of the folly of those who differ from them. Hence, in the critical aspect of Logic, the order of applying the logical processes is the reverse of what it is in the use of Logic as an organon or instrument of invention. There the order is to commence with the analysis of the term, and then to proceed to the synthesis of terms in propositions, syllogisms, and extended discourse; here we commence with the complex result, and by analysis resolve it into its elements.

§ 116. OF THE USE OF ANALYSIS GENERALLY.—In the use of Logic, whether for invention or for criticism, analysis and synthesis are equally indispensable; but the latter, after the former has been effected, is largely a natural and spontaneous process, and presents but little difficulty in its performance. On the other hand, analysis, while to a certain extent also spontaneous, requires, for its efficient performance, the most vigorous and protracted exertion of the mental faculties, as, e. g., in the mathematics,- and hence is at once the most important and the most difficult of the logical processes. It will therefore require our special attention.

We have distinguished between the inventional and the critical functions of Logic, and

also with reference to the use of the logical processes as applied in the performance of the one or the other function; and with reference to invention, we have regarded the function of analysis as limited to the analysis of terms, with a view to an apprehension of the notions expressed by them. In practice, however, it is difficult to distinguish between the uses of analysis for invention and for criticism. For, as we have observed, the human mind is so constituted that the synthetical process is performed spontaneously and involuntarily. Hence there is no subject that can present itself for our investigation which we can approach unembarrassed by opinions already formed; and, indeed, until such opinions or theories are formed, the process of investigation cannot commence. Hence, as is generally recognized, the method of scientific investigation must consist largely in the forming of theories and their subsequent investigation. We may distinguish, however, between our own theories, either accidentally formed or formed for the purpose of the investigation of a proposed subject, and the theories formally propounded by others, either in writing or speech; and we may conveniently regard the former as belonging to the function of invention, and the latter to that of criticism. The latter, as being the simpler subject, will be first considered.

§ 117. (1) OF THE USE OF ANALYSIS IN CRITICISM. In this case the function of analysis extends to the analysis of all forms. of language, from the term to the extended discourse or argument; and, as we have observed, it commences with the latter, which is in fact the most difficult task. For here it is necessary to determine from the loose and inaccurate expressions of ordinary disquisition the precise nature of the conclusions asserted and of the arguments used to establish them; and this task is always difficult, and sometimes impossible. When these matters have been determined it will be necessary also to analyze carefully every syllogism, proposition, or term involved in the course of the reasoning. But this in general, to the trained logician, presents but little difficulty.

§ 118. (2) OF THE USE OF ANALYSIS IN INVENTION.-Strictly speaking, this perhaps extends only to the analysis of the term with a view to simple apprehension, and in a previous passage we have so regarded it. But before this task can be approached, it is necessary for us to determine the nature of the precise questions to be investigated; and this will require an analysis of the facts involved in the investigation, and also of the opinions or theories with regard to those facts casually existing in the mind. For, as will be explained more fully in

the next chapter, the questions demanding investigation are in general determined by the nature and the conditions of the problems involved; and it is essential to a rational investigation that the issues thus involved be clearly ascertained. When the issues or questions are thus determined and logically expressed, our investigation is then narrowed to the determination of the truth of one of two alternative propositions, which are called the thesis and the anti-thesis, and of which one or the other must be true; and thus our task is in general greatly facilitated. The use of this sort of analysis finds its best illustration in the practice of the lawyers, with whom it is an imperative rule that the first step in the investigation of a case must consist in settling the issues. In ordinary discourse this task is almost always neglected, and, as will be seen as we proceed, this is one of the most fruitful sources of fallacy.

119. OF ANALYSIS AND SYNTHESIS GENERALLY.-This subject is one of extreme importance, and to the advanced student should constitute one of the principal subjects for his meditations; but for the purposes we have in view it may be sufficiently developed by a statement of the practical rules by which the reasoner should be governed, which will be given at length in the next chapter.

CHAPTER VII

THE RULES OF LOGIC

I

OF THE RULES OF LOGIC GENERALLY

§ 120. SCOPE OF THE RULES OF LOGIC.According to the view we have taken in this essay, inference is only one of the processes of ratiocination. Judgment is also a ratiocinative process, and, like inference, must have its rules by which false or pretended judgments may be distinguished from the real. Moreover, where our reasoning is not apodictic, we have to use assumed propositions, or assumptions, as premises; and though it is said that Logic is not concerned with the truth or falsity of these, yet this is true only in a qualified sense. For where the falsity of such propositions can be detected by logical processes,-i. e., by definition, judgment, and inference, -it is the function of Logic to condemn and reject them; precisely as in the case of self-contradictory