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with this northern part of the island, in adopting, about the same period, the same phrase, as a sort of philosophical watch-word;—that, although their views differ widely in various respects, they have in general been classed together as partisans of a new sect, and as mutually responsible for the doctrines of each other. It is easy to perceive the use likely to be made of this accident by an uncandid antagonist.

All of these writers have, in my opinion, been occasionally misled in their speculations, by a want of attention to the distinction between first principles, properly so called, . and the fundamental laws of human belief. Buffier himself has fallen into the same error; nor do I know of any one logician, from the time of Aristotle downwards, who has entirely avoided it.

The foregoing critical remarks will, I hope, have their use in keeping this distinction more steadily in the view of future inquirers; and in preventing some of the readers of the publications to which they relate, from conceiving a prejudice, in consequence of the looseness of that phraseology which has been accidentally adopted by their authors, against the just and important conclusions which they contain.

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CHAPTER SECOND.

OF REASONING AND OF DEDUCTIVE EVIDENCE.

SECTION I.

Doubts with respect to Locke's Distinction between the Powers of Intuition and of Reasoning.

ALTHOUGH, in treating of this branch of the Philosophy of the Mind, I have followed the example of preceding writers, so far as to speak of intuition and reasoning as two different faculties of the understanding, I am by no means satisfied that there exists between them that radical distinction which is commonly apprehended. Dr. Beattie, in his Essay on Truth, has attempted to show, that, how closely soever they may in general be connected, yet that this connection is not necessary; insomuch, that a being may be conceived endued with the one, and at the same time destitute of the other.* Something of this kind, he remarks, takes place in dreams and in madness; in both of which states of the system, the power of reasoning appears occasionally to be retained in no inconsiderable dégree, while the power of intuition is suspended or lost. But this doctrine is liable to obvious, and to insurmountable objections; and has plainly taken its rise from the vagueness of the phrase common sense, which the author employs through the whole of his argument, as synonymous with the power of intuition. Of the indissoluble connection between this last power and that of reasoning, no other proof is necessary than the following considera

* Beattie's Essay, p. 41, 2d edit.

tion, that, “in every step which reason makes in demon"strative knowledge, there must be intuitive certainty;" a proposition which Locke has excellently illustrated, and which, since his time, has been acquiesced in, so far as I know, by philosophers of all descriptions. From this proposition (which, when properly interpreted, appears to me to be perfectly just) it obviously follows, that the power of reasoning presupposes the power of intuition; and, therefore, the only question about which any doubt can be entertained is, Whether the power of intuition (according to Locke's idea of it) does not also imply that of reasoning? My own opinion is, decidedly, that it does; at least, when combined with the faculty of memory. In examining those processes of thought which conduct the mind by a series of consequences from premises to a conclusion, I can detect no intellectual act whatever, which the joint operation of intuition and of memory does not sufficiently explain.

Before, however, proceeding farther in this discussion, it is proper for me to observe, by way of comment on the proposition just quoted from Locke, that, although, “in a

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complete demonstration, there must be intuitive evidence "at every step," it is not to be supposed, that, in every demonstration, all the various intuitive judgments leading to the conclusion are actually presented to our thoughts. In by far the greater number of instances, we trust entirely to judgments resting upon the evidence of memory; by the help of which faculty, we are enabled to connect together the most remote truths, with the very same confidence as if the one were an immediate consequence of the other. Nor does this diminish, in the smallest degree, the satisfaction we feel in following such a train of reasoning. On the contrary, nothing can be more disgusting than a demonstration where even the simplest and most

obvious steps are brought forward to view; and where no appeal is made to that stock of previous knowledge which memory has identified with the operations of reason. Still, however, it is true, that it is by a continued chain of intuitive judgments, that the whole science of geometry hangs together; inasmuch as the demonstration of any one proposition virtually includes all the previous demonstrations to which it refers.

Hence it appears, that, in mathematical demonstrations, we have not, at every step, the immediate evidence of intuition, but only the evidence of memory. Every demonstration, however, may be resolved into a series of separate judgments, either formed at the moment, or remembered as the results of judgments formed at some preceding period; and it is in the arrangement and concatenation of these different judgments, or media of proof, that the inventive and reasoning powers of the mathematician find so noble a field for their exercise.

With respect to these powers of judgment and of reasoning, as they are here combined, it appears to me, that the results of the former may be compared to a collection of separate stones prepared by the chisel for the purposes of the builder; upon each of which stones, while lying on the ground, a person may raise himself, as upon a pedestal, to a small elevation. The same judgments, when combined into a train of reasoning, terminating in a remote conclusion, resemble the formerly unconnected blocks, when converted into the steps of a staircase leading to the summit of a tower, which would be otherwise inaccessible. In the design and execution of this staircase, much skill and invention may be displayed by the architect; but, in order to ascend it, nothing more is necessary than a repetition of the act by which the first step was gained. The fact I conceive to be somewhat analo

gous, in the relation between the power of judgment, and what logicians call the discursive processes of the understanding.

Mr. Locke's language, in various parts of his Essay, seems to accord with the same opinion. "Every step in

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reasoning, (he observes) that produces knowledge, has "intuitive certainty; which, when the mind perceives, "there is no more required but to remember it, to make "the agreement or disagreement of the ideas, concerning "which we inquire, visible and certain. This intuitive "perception of the agreement or disagreement of the inter"mediate ideas, in each step and progression of the "demonstration, must also be carried exactly in the mind, “and a man must be sure that no part is left out; which, "in long deductions, and in the use of many proofs, the "memory does not always so readily and exactly retain : "therefore it comes to pass, that this is more imperfect "than intuitive knowledge, and men embrace often, false"hood for demonstrations."*

The same doctrine is stated elsewhere by Mr. Locke, more than once, in terms equally explicit ;† and yet his language occasionally favours the supposition, that, in its deductive processes, the mind exhibits some modification of reason essentially distinct from intuition. The account, too, which he has given of their respective provinces, affords evidence that his notions concerning them were not sufficiently precise and settled. "When the mind (says "he) perceives the agreement or disagreement of two "ideas immediately by themselves, without the interven❝tion of any other, its knowledge may be called intuitive. "When it cannot so bring its ideas together as, by their "immediate comparison, and, as it were, juxta-position, or

*B. IV. chap. ii. § 7. See also B. IV. chap. xvii. § 15.

‡ B. IV. chap. xvii. § 2. B. IV. chap. xvii. § 4. § 14.

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