792 LOGIC
the further idea of the nature of knowledge and the ultimate constitution of that which is to be known. When this point is reached, a radical divergence presents itself between the views of Descartes and Bacon, consequent on which appears a radically divergent statement of the main processes and methods of logical theory.
To Descartes the ideal of cognition is the mathematical, that in which from assured and distinct data we proceed by strict sequence of proof to determine accurately and completely the nature of complex phenomena. Such an ideal, extended so as to embrace knowledge as a whole, dominates the whole of the Cartesian speculation, and, as in the case of the Socratic doctrine of knowledge, is the ground of the Cartesian doubt. Perfect certainty, i.e., clearness and distinctness of principles, logical consecutiveness of deduction from them, and exhaustive enumeration of details – such are the characteristics of completed knowledge. There follow naturally therefrom the main processes of knowledge: – intuition, by which the simple data and axioms are apprehended; induction, or exhaustive enumeration of the elementary factors of any phenomenon; deduction, or determination of the complex as the necessary result of the combination of simple factors. To the processes of induction and deduction, when viewed more generally, the titles analysis and synthesis may be given.[1] On other portions of logical theory Descartes does not enter, and the text-books of the Cartesian school, even the celebrated Port Royal logic, do little more than expound with some freshness such of the older material as seemed capable of harmonizing with the new conception.
Two things only require note in respect to the Cartesian logic, apart from its freshness and completeness; the one is the obscurity which hangs over the nature of intuition; the other is the step in advance of the scholastic logic effected in the assimilation of deduction to synthesis. As regards the first, the criteria laid down by Descartes, viz., clearness and distinctness, are unsatisfactory and ambiguous. It is evident that he implied under these clear and distinct recognition of necessity in the data or principles, but the nature of this necessity is never made clear.[2] As regards the second, it was of importance to signalize, as against the scholastic view, that the universal in thought or reasoning was not only of the nature of the class notion, that genera and species were not the ultimate universals, but were themselves secondary products, formed by reasoning, and based upon essential connexion of facts. In this Descartes was but returning to the genuine Aristotelian doctrine, but his view has all the advantage derived from a truer and more scientific conception of what these connexions in nature really are.
22. What is peculiar in the logic of Bacon springs likewise from the peculiarities of the underlying conception of nature, The inductive method, expounded in the Novum Organum, is, however, only part of the Baconian logic, and, since it is commonly regarded as being the whole, a brief statement of what Bacon included under logic may here be given.
Viewing logic as the doctrine which deals with the use and object of the intellectual faculties, Bacon divides it (in this approximating somewhat to the extended division of the Stoic logicians) into (1) the art of inquiry or invention, (2) the art of examination or judgment, (3) the art of memory, and (4) the art of elocution or tradition. The third and fourth divisions are unimportant; the first and second might be called respectively the theory of the acquisition of knowledge and the theory of evidence or proof. The art of inquiry is subdivided into the art of the discovery of arts and the art of the discovery of arguments. The second of these Bacon regards as identical with the Topics of the Greek and Roman dialectic, and therefore as of comparatively slight value. Of the first there are two main branches: – (A) Experientia Literata and (B) Interpretatio Naturæ. The art of judgment has two subdivisions: – the examination of methods of reasoning – induction and syllogism – which resembles the older analytic; and the examination of errors of reasoning – whether these be sophistical, i.e., the logical fallacies of the older doctrine, or errors of interpretation to be removed by careful criticism of scientific terms, or arising from erroneous tendences of the mind (the doctrine of idola) – which resembles the older treatment of Elenchi.
The peculiarity of the Baconian logic, then, must be sought in the processes included under the art of discovering arts or knowledge. Among these the syllogism is not included. It is a process with no practical utility; it involves premisses of which the truth is simply assumed, and consequently its conclusions can have no validity beyond that of the premisses; it affects to determine the particular from the general, but in fact nature is much more subtle than intellect, and our generalizations, which are but partial abstractions, are quite inadequate to afford exhaustive knowledge of the particular; it throws no light upon the essential part of cognition as a process in formation, viz., the method by which we are to obtain accurate notions of things, and judgments based on these notions. Moreover, the deductive or syllogistic procedure favours and encourages the tendency to rash generalization, to the formulation of a universal axiom from few particulars, and to the uncritical acceptance of experience. If syllogism exist at all, there must be a prior process, that of generalizing by rigid and accurate methods from experience itself. Syllogism is not entirely worthless. It is of particular service in some branches of science (e.g., the mathematical), and generally may be employed so soon as the principles of a science are well established; but it is a subordinate and secondary method.
The art of discovery, then, is the method of generalizing from experience. What this method shall be depends entirely on the thinker's conception of experience. Now Bacon's conception is perfectly definite. Observation presents to us complex natures which are the results of simpler, more general forms or causes. From the complex phenomena these forms are to be sifted out by a methodical process of analysis and experiment. A general proposition is one stating the connexion between complex natures and their simple forms or causes; it is, therefore, the result of a graduated process. No doubt there may be generalizations based only on an ingenious comparison of the complex phenomena as they are presented to us; such a process Bacon calls Experientia Literata, and the maxims recommended for it much resemble the ordinary methods of experiment, but truly scientific knowledge is only to be obtained by the complete inductive method. The characteristics of this inductive method follow at once from the nature of the object in view. The form which is sought can be detected only by examination of cases in which the given complex effect is present, in which it is absent, and in which it appears in different degrees or amounts. By a critical comparison of these cases we may be able to detect, and, were the enumeration exhaustive, we must infallibly detect, by process of exclusion or elimination, a phenomenon constantly present when the effect is present, absent whenever the effect is absent, and varying in degree with the effect. Such a phenomenon would be the form in question, – the cause of the given fact or attribute. Exhaustive enumeration is, of course, an ideal, and therefore the method of exclusion can never be perfectly carried out, but all additional aids have significance only as supplying in part the place of exhaustive enumeration. We may, on the basis of a wide examination, frame a first generalization (first vintage as Bacon metaphorically calls it), and proceed to test its correctness by carrying out the critical comparison with it in view. Or we may, under the guidance of our leading principle, take advantage of certain typical cases presented by nature, or force cases by experiment in such a way as to supersede the enumeration. There are prerogative instances, critical phenomena, helpful in discovery of the cause of a phenomenon. Of other adminicula, or aids to induction, only the titles are given by Bacon, and it would be hazardous to conjecture as to their significance.[3]
The Baconian logic, then, or at least what is peculiar to it, is thoroughly conditioned by the peculiarities of the Baconian metaphysic or conception of nature and natuial processes. As to the novelty of the logic, this to us does not appear to lie in the mere fact that stress is laid upon induction, nor do we think it correct to assign to Bacon the introduction of the theory of induction as an integral portion of logic. But it consists in the new view taken of what constitutes the universal in thought, a view which may be inadequate, but which colours and affects every process of thought, and therefore every portion of logical theory. It is but a consequence of Bacon's narrow view of the essence of syllogism that he should set induction in opposition to deduction, and regard syllogism as of service only for communication of knowledge. His inductive methods are throughout syllogistic in this respect, that they like all processes of thought involve the combination of universal and particular. Experience is interpreted, that is to say, viewed under the light of a general idea or notion.
Logic on the Basis of Psychological Empiricism. Locke, Hume, Mill, Condillac.
23. The universal element in thought which is recognized by Bacon as present received from him no special treatment. His theory of the nature of knowledge offered no explanation of the origin, significance, and validity of the notions involved in inductive procedure. The Essay on the Human Understanding, which carries out in the domain of inner experience the practical tendency of the Baconian method, supplied from the point of view of individualism the metaphysical theory common to both, a certain psychological theory of the universal element in knowledge, and thereby afforded a new foundation for logical doctrines. The Essay contains, in an unsystematic fashion, much that bears directly on logic (e.g., the whole discussion on names, the classification of the signification of
- ↑ See Regulæ ad directionem ingenii, Nos. 2, 3, and especially 7. The celebrated rules of speculation (De Methodo) are only a more popular statement of the same processes.
- ↑ His ultimate standard is, no doubt, necessity for a thinking subject Whatever is so connected with the existence of the thinking being that without it this existence is incomprehensible is necessary. But to apply this ideal to any proposition save the first, the Cogito ergo sum, is for Descartes the fundamental difficulty of his philosophy.
- ↑ Nov. Org., ii. 21. In addition to prerogative instances there are mentioned – supports of induction; rectification of induction; variation of the investigation according to the nature of the subject; prerogative natures: limits of investigation; application to practice; preparations for investigation; ascending and descending scale of axioms.
