custom, to pass from the impression or idea of an object to the idea of that object which usually attends it. The causal relation between things and ideas involved in the theory of Locke, Hume regarded as a mere assumption which experience did not justify. “The mind,” he says, "has never anything present to it but the perceptions, and cannot possibly reach the experience of their connection with objects. The supposition of such a connection is, therefore, without any foundation in reasoning." The ultimate realities, then, with which the mind has to deal are individual, unreferable impressions, and from such impressions we cannot infer the existence of external material objects. Here we see idealism pure and simple.

But he did not rest content with a denial of the reality of an external world; he also denied the reality of the soul. "Since all our perceptions are different from each other, and from everything else in the universe, they are also distinct and separable, and may be considered as separately existent, and may exist separately, and have no need of anything else to support their existence."* Hence there is no necessity of a self as a substratum or subject of our perceptions. Proceeding upon his original thesis, that the perceptions of the mind are resolvable into impressions and ideas-ideas being mere images of impressions -he says: "If any impression gives rise to the idea of self, that impression must continue invariably the same, through the whole course of our lives; since self is supposed to exist after that manner. But there is no impres

* 66 Treatise," p. 5г8.

sion constant and invariable. Pain and pleasure, grief and joy, passions and sensations succeed each other, and never all exist at the same time. It cannot, therefore, be from any of these impressions, or from any other, that the idea of self is derived, and consequently there is no such idea." * Hume thinks we have no more an idea of a thinking substance as the support of perceptions than we have of an external substance as the support of qualities, and Berkeley in rejecting the one ought to have rejected the other.†

To make his scepticism complete, Hume impeaches the veracity of reason: (1) Because it leads to conclusions different from those of the senses; (2) Because it is so frequently found to be fallible. (3) Because each judgment must be tested by other judgments “containing uncertainty," and these in turn by other judgments containing uncertainty, and so on ad infinitum. Nihilistic scepticism is the fruit of Hume's endeavors. I

Thus, in our brief historical survey of modern philosophy down to Hume, we find it culminating in scepticism. The subjectivity which characterizes it from the beginning peculiarly paves the way toward the conclusion. It was against this scepticism that Reid recoiled. Repugnant as it was to him, and, as before stated, be lieving it to be "inlaid" in all modern philosophy, and traceable to the theory of perception which he believed. to be common to these systems, § he determined to make a new inquiry into the subject, with the pur

* "Treatise," p. 533. Ibid., p. 472, sq.

† Ibid., pp. 517-18.

"Works," Inq., pp. 96, 103, 106.

pose of refuting this theory of perception, and placing philosophy upon a new basis, by substituting a new theory of perception, and a new philosophical organon in the principle of common sense.

In inquiring anew into this subject, Reid adopted a particular method. The "Inquiry" especially bears the marks of its age. Like other systems of philosophy, it is affected by the "Zeit-Geist." It is not often, if ever, that we have a purely closet philosophy—a philosophy produced absolutely independent of the spirit of the age. Consciously or unconsciously speculation is affected by the subtle influences of the intellectual and moral atmosphere in which it is brought forth. This influence of the spirit of the age upon Reid's philosophy may be seen in the method which he adopts-the experimental or inductive method. The results of an application of this method in the study of physical phenomena, by such men as Newton, were wonderful. Reid, who was an earnest student of physics, was greatly impressed by the validity and fruitfulness of this method, and he came to the conclusion that it was the only method which should be employed in the investigation of the phenomena of the mind, and determined to apply it. All through the "Inquiry" the steadfastness of his purpose is manifest. Dugald Stewart truly remarks, that the influence of the general view opened in the 'Novum Organon' may be traced in almost every page of his writings: and, indeed, the circumstance by which these are so strongly and characteristically distinguished, is that they exhibit the first systematical attempt to exemplify in the study of human nature the same plan of

investigation which conducted Newton to the properties of light and to the law of gravitation." *

Having thus stated the aim and method of Reid's philosophy, let us proceed to an exposition of the same. And, first, let us consider the theory of perception, which he urged in opposition to the "theory of ideas."

His theory of perception has both negative and positive aspects. In its negative aspect, it is a denial of (1) the particular form of perception which Reid ascribed to all preceding philosophy. This particular form Reid conceived to be, as Hamilton suggests, that the object before the mind in perception is "always a tertium quid numerically different both from the object existing and from the subject knowing." This is the theory which Reid felt called upon to deny—the calling into question of which he deemed to be the special merit of his own philosophy. (2) In its negative aspect, Reid's theory of perception is a denial that we attain our knowledge of external objects by an act of reasoning.

In denying the theory of ideas his argument runs as follows: §

1. The theory is in direct opposition to the universal sense of men uninstructed in philosophy. When a plain man sees the sun and moon he does not doubt that there are objects far distant from himself, and not merely ideas in his mind. If he asks whether there are no substantial beings called sun and moon, the answer which he will

* "Collected Works," vol. x, p. 259.

† Works, Inq., Note, p. 106.

Ibid., p. 88.

§ Cf. "Works," Inq., pp. 201-11 and especially I. P., pp. 298-309.

get from the philosophers will differ. Locke and his predecessors will answer, that there are such beings, but they never appear to us in person, but only by ideaswhich are their representatives in our minds, and all we know of them must be gained from these ideas. Berkeley and Hume would say, that there are no such substantial beings. That is simply a prejudice of the vulgar. Berkeley would say that nothing exists but ideas and minds, and these things are simply ideas in our minds. Hume would say, only ideas exist, and the mind is simply a series of ideas bound together by a few relations. To the plain man this must, of course, be opposed to "the dictates of common understanding."

2. Those who advocate the "theory of ideas" have, as a rule, assumed the existence of the ideas, and have regarded their existence as unquestionable. The few arguments which they have incidentally offered in their behalf have been "too weak to support the conclusion." Locke, for example, says we are conscious of such ideas. But, says Reid, we are not conscious of them. All we are conscious of, are the operations of the mind, such as perceiving, remembering, etc., and not of the objects of such operations. And thus he quotes others, endeavoring to show the assumptive character of their positions, and the weakness of their "incidental arguments.”

3. Although there is a unanimous agreement among philosophers on the subject of the existence of ideas, there seems to be a pronounced disagreement among them with respect to everything else concerning the ideas. This ought not to be, if they are a reality, for of all things they ought to be most easily accessible to knowledge. Some hold that they are self-existent; others, that they