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mer on this subject, as in every instance unexceptionable; nor do I think it has been a fortunate circumstance, (notwithstanding the very high authorities which may quoted in his vindication,) that he attempted to incorporate so vague and ambiguous a phrase with the appropriate terms of logic. My chief reasons for this opinion I have stated at some length, in an account published a few years ago of Dr. Reid's Life and Writings.*

One very unlucky consequence has unquestionably resulted from the coincidence of so many writers connected 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

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In consequence of the ambiguous meaning of this phrase, Dr. Reid sometimes falls into a sort of play on words, which I have often regretted. "If this be philosophy," says he, on one occasion, "I renounce her guidance. Let my soul dwell with common sense." (Inquiry into the Human Mind, Chap. i. § 3. See also § 4. of the same chapter.) And in another passage, after quoting the noted saying of Hobbes, that "when reason is against a man, a man will be against reason;" he adds, "This is equally applicable to common sense." (Essays on the Intellectual Powers, p. 530. 4to edition.) In both of these instances, and, indeed, in the general strain of argument which runs through his works, he understands common sense in its ordinary acceptation, as synonymous, or very nearly synonymous, with the word reason, as it is now most frequently employed. In a few cases, however, he seems to have annexed to the same phrase a technical meaning of his own, and has even spoken of this meaning as a thing not generally understood. Thus, after illustrating the different classes of natural signs, he adds the following sentence: "It may be observed, that as the first class of natural signs I have mentioned is the foundation of true philosophy, and the second of the fine arts or of taste, so the last is the foundation of common sense; a part of human nature which hath never been explained.” Inquiry, Chap. v. § 3.

See Note (D.)

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.

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 connexion 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 degree, 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 connexion between this last power and that of reasoning, no other proof is necessary than the following consideration, that, "In every step which reason makes in demonstrative knowledge, there must be intuitive certainty;" a proposition which Locke has excellently

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

illustrated, and which, since his time, has been acquiesced in, so far as I know, by philosophers of all descrip tions. 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 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 on 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 analogous, 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 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 intermediate 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