number by present reflections and passions, and in storing the memory with ideas. The same continu'd and uninterrupted Being may, therefore, be sometimes present to the mind, and sometimes absent from it, without any real or essential change in the Being itself."

It will be noted that Hume here regards things not only as possessing being independently of the mind, but also as identical with perceptions when present to the mind. Indeed, he was first convinced of their identity with perceptions, and suggested their independence only as an afterthought. In this respect Hume's view is to be distinguished from the "natural realism" of the Scottish School of Reid and Hamilton. These writers were concerned primarily to avert the sceptical and absurd consequences of the "ideal philosophy," which merged external reality into the mind's ideas. They sought to restore the traditional substances, the mind within and the nature without; and regarded both as distinct from the ideas that "suggest" them. In the case of the "primary" physical qualities, "extension, solidity, and motion," they did, it is true, assert a doctrine of "real presentationism." But they did not explain how bodies can be "suggested," "presented," or "conceived," without becoming ideas; or how without the mediating function of ideas, minds can know bodies. In other words, the dualistic difficulty was aggravated and not relieved.2

Modern realism is closer to the monistic realism of "ideas," suggested by Hume, than to the dualistic realism of mind and matter, propounded by the Scottish School; and this in spite of the fact that the Scottish philosophy was primarily a polemic, in the name of "realism," against

1 Hume: Treatise of Human Nature (Selby-Bigge's edition), p. 207. Cf. above, pp. 137-138. Professor W. P. Montague called attention to this aspect of Hume in an article entitled "A Neglected Point in Hume's Philosophy," Phil. Review, Vol. XIV, 1905.

Thomas Reid: Inquiry into the Human Mind (1764), ch. I, V, VII; Sir William Hamilton: Notes B, C, D, appended to his edition of the Philosophical Works of Thomas Reid; especially, eighth edition, p. 825. Cf. J. S. Mill: Sir William Hamilton's Philosophy, Ch. II.

Hume, as the last and most outrageous of the idealists. The new realism, while it insists, as all realism must, that things are independent, asserts that when things are known, they are ideas of the mind. They may enter directly into the mind; and when they do, they become what are called 'ideas.' So that ideas are only things in a certain relation; or, things, in respect of being known, are ideas.

It is important, therefore, in expounding the general realistic theory of knowledge, to distinguish two component theories. The first I shall call the theory of 'immanence.' This is the same theory as that which I have in another connection termed 'epistemological monism.'1 It means that when a given thing, a, is known, a itself enters into a relation which constitutes it the idea or content of a mind. The second I shall call the theory of 'independence;' and it means that although a may thus enter into mind, and assume the status of content, it is not dependent on this status for its being, or nature. After discussing these two theories, which deal with the problem of the relation of knowledge to its objects, I shall apply them briefly to the problem of truth.

§ 2. There are two varieties of dualism which the theory of immanence makes it possible to escape; the dualism

The Duality of Mind and

Body as a Dif

ference of Organization

between mind and body, and the dualism between thought and things. The theory of immanence escapes these dualisms by employing the notion of relation in place of the notion of substance.2

The dualism between mind and body received its classic formulation, as we have seen, in the philosophy of Descartes. This was essentially a 'substance-attribute'

1 Cf. above, pp. 124-126.

It has been suggested that the categories of substance, quality, and relation represent natural stages in the evolution and refinement of thought. Cf. Ludwig Stein: "Der Neo-Idealismus unserer Tage," in his Archiv für systematishe Philosophie, Vol. IX, 1903; referred to by W. P. Montague: "The Relational Theory of Consciousness and its Realistic Implications," Jour. of Phil., Psych., and Scientific Methods, Vol. II, 1905.

philosophy. Mind and body were conceived as two selfcontained and mutually exclusive spheres, characterized and distinguished by the two attributes, 'thought' and 'extension.' These two attributes Descartes regarded as ultimately different, and as involving a complete disjunction between the substances which they qualified. The Cartesian dualism gave rise to the most baffling perplexities. If mind and body be disjoined by definition, how explain the empirical fact of their union? For those facts which are so prominently in evidence in philosophy, namely, the processes of perception and of voluntary action, are neither exclusively mental nor exclusively bodily, but a blend of the two. In perception a process which begins as bodily ends as mental; and in volition a process which begins as mental ends as bodily. Notwithstanding these difficulties the Cartesian dualism has been perpetually confirmed by the habits of common sense; and still remains the most plausible, and superficially the most intelligible, doctrine. For it is customary and instinctive to think of all duality as exclusive, like the duality of bodies or non-intersecting spaces. Gesture and symbol-in short, every method of sensuous representation, exhibit the same type of duality; so that it requires more than the ordinary precision of thought to avoid the assumption of its universality.

Human experience abounds, however, in dualities of another type. Social aggregates, for example, are distinguished not by the inherent nature of their contents, but by some unifying relation. Thus the residents of the United States are divided into sexes, political parties, races, ages, and innumerably many other groups; and these groups overlap and intersect. They do not possess their members exclusively, but share their members. The difference between any two groups, such, for example, as the Democratic party and the proletariat, is not a difference of members for it is conceivable that their membership should exactly coincide; but a difference of

principle of organization. In respect of one relation the members constitute one group, and in respect of another relation the same members constitute another group.

The theory of immanence applies this type of difference to the duality of mind and body. The application becomes possible, indeed necessary, the moment it is recognized that mind and body are both complexes capable of being analyzed into more primitive terms./ Neither mind nor body is really simple; although common sense and philosophical tradition have conspired to make them appear so.1 And when they are submitted to analysis, it appears that the more primitive terms of which they are composed are, in many cases at least, interchangeable. There are sensible qualities and logical categories common to both. Indeed it is impossible to find ground for asserting that there is any term of the bodily complex that is disqualified from entering the mental complex.

This view is best set forth in Ernst Mach's little book, Die Analyse der Empfindungen, which deserves to be numbered among the classics of modern realism. The elements of the physical and the psychical, according to this author, are the same. But while physics studies one type of relationship, such as the relation of a color to the source of light, psychology studies its peculiar relation to the retina or nervous system of a sentient organism. The color itself is neither physical nor psychical.

While Mach's statement of the theory is correct in principle, it is colored by the author's naturalistic predilections. He neglects the logical aspect of knowledge. Physical and psychical complexes have in common not only sensible qualities, but also certain more fundamental formal relationships, such as implication, order, causation, time, and the like. These relations in their purity can be discovered only by carrying analysis beyond the bounds 1 Cf. above, pp. 51-53, 279-283.

There is an English translation by C. M. Williams, already referred to above, pp. 78-79. Cf. also Mach: Erkenntnis und Irrtum. ⚫ Cf. above, pp. 277-279; and below, pp. 364-365.

of sensible discrimination. They require, in short, logical analysis.1 Those who have adequately recognized the importance of logic have, on their side, usually neglected the specific question of the relation of mind and body. The full scope of the theory of immanence appears only when it is recognized that the same elements compose both mind and body; and that these common elements embrace both sense qualia and also logical abstractions. Then, instead of conceiving of reality as divided absolutely between two impenetrable spheres, we may conceive it as a field of interpenetrating relationships, among which those described by physics and psychology are the most familiar and typical, and those described by logic the most simple and universal.

When mind and body are so conceived, there is no longer any peculiar difficulty involved in the perception of bodily objects. For the relationship which invests a term with a bodily character does not preëmpt it; so that at the same time that it is bodily by virtue of one relation, it may also be content of perception by virtue of another relation. When I perceive Mars, the sun's satellite (body) is my percept (mind); and there is no more contradiction than in supposing that my uncle is my father's brother. 83. The second dualism which the theory of immanence makes it possible to escape is that between knowledge and things. This dualism is not based merely on a Representation as an Immanent disjunction of substances defined by dissimilar Relation attributes, but on the alleged 'self-transcendence' of knowledge. It would appear that knowledge is 'about' things other than itself. This has given rise to the notion of the 'thing in itself,' as that to which knowledge points or refers, but which is always 'other' than the content of knowledge. The difficulty is evident. All qualities and characters, in so far as known, are annexed by knowledge and withdrawn from reality. The thing

1 Cf. above, p. 108.

* Nor in the voluntary control of bodily actions. Cf. below, pp. 341–342.