tion we not only cognize the external world, but distinguish it from ourselves, we apprehend the existence of matter and mind as separate. Natural Realism involves Natural Dualism.

Latent Modifications of the Mind: Memory and the Association of Ideas. The most important problem in this connection is, not the explanation of the phenomenon of retention, for that follows easily from the "self-energy" of the mind, and is "involved in the very conception of its power of self-activity," but the phenomenon of forgetfulness, or the vanishing of a mental activity. How can an activity which has once existed be abolished "without a laceration of the vital unity of the mind as a subject, one and indivisible?" The solution of this problem is to be sought for in the theory of obscure or latent modifications or mental activities, real, but beyond the sphere of consciousness. The infinitely greater part of our spiritual treasures lies always beyond the sphere of consciousness, hid in the obscure recesses of the mind. There are two degrees of latency: first, one such that the latent knowledge may be applied how and when we will to apply it; second, one such that whole systems of knowledge may lie unconsciously in the mind, unless by some abnormal condition of mind they are thrown into consciousness. Latent modifications are explained by the hypothesis of the constancy of the quantum of mental energy with a continual change of the ideas among which this energy is distributed, the newer ideas naturally attracting to themselves a relatively larger amount of that energy, and the older being crowded out of consciousness. Though memory is known to be greatly dependent on corporeal conditions, latent modifications do not admit of a physiological or materialistic deduction: they must be referred to the unity and self-activity of mind, in virtue of which mental activities which have once been determined persist. By this conception of latent modifications may be explained the Association of Ideas, the general law of which (which may be called the Law of Redin

tegration) is that "thoughts which have once co-existed in the mind are afterwards associated, or that those thoughts suggest each other which had previously constituted parts of the same entire or total act of cognition."

Necessary Cognition. The marks of necessary truth are, incomprehensibility (or inexplicability), simplicity, necessity and universality, comparative evidence and certainty. Necessity is positive or negative. Positive necessity occurs when a proposition is conceivable and its contradictory opposite is inconceivable; negative, when the proposition and its contradictory opposite are both equally conceivable. According to the logical law of the "Excluded Middle," one of the propositions must be true; hence inconceivability is not a test of truth. Space-to take an illustration - cannot be conceived either as finite or as infinite; but it must be one or the other of these. The same is true as regards time also. From the foregoing it follows that only positive necessity is a test of truth. Examples of positively necessary notions are existence and its modifications, identity, contradiction, "excluded middle," the intuitions of space and time. The positively necessary notions may be described as "so many positive exertions of mental vigor; " the negatively necessary notions are, on the other hand, consequences of the "imbecility of the human mind." The truth of one of the inconceivable mutually contradictory notions may sometimes (as in the case of the notion of freedom, which is postulated by the moral faculty) be shown by non-theoretical considerations.

The Law of the Conditioned and its Applications: Causation. It is a law of finite, or human, thought that the conceivable is in every relation bounded by the inconceivable, or, more definitely, "All positive thought lies between two extremes, neither of which we can conceive as possible, yet as mutual contradictions the one or the other we must recognize as necessary." This law receives exemplification in our formation of judgments of causation. "When we are aware of something which begins to be,

we are by the necessity of our intelligence constrained to believe that it has a cause. But what does the expression that it has a cause signify? If we analyze our thought, we shall find that it simply means that as we cannot conceive any new existence to commence, therefore, all that now is seen to arise under a new appearance had previously an existence under a prior form. We are utterly unable to realize in thought the possibility of the complement of existence being increased or diminished. We are unable, on the one hand, to conceive nothing becoming something, or, on the other, something becoming nothing. Ex nihilo nihil, in nihilum nil posse reverti, expresses in its purest form the whole intellectual phenomenon of causality." Between causes and effects there is an "absolute tautology, cause and effect have the same content, only in different forms. "Gunpowder is the effect of a mixture of sulphur, charcoal, and nitre, and these three substances again are the effect ― result — of simpler constituents, and these constituents again of simpler elements either known or conceived to exist. Now, in all these series of compositions we cannot conceive that aught begins to exist. The gunpowder, the last compound, we are compelled to think, contains precisely the same quantum of existence that its ultimate elements contained prior to their combination. Well, we explode the powder. Can we conceive that existence has been diminished by the annihilation of a single element previously in being, or increased by the addition of a single element which was not heretofore in nature? 'Omnia mutantur: nihil interit,' is what we think, what we must think." The principle that every event should have its cause is necessary and universal, and is imposed on us as a condition of our human intelligence. As to the origin of the principle of causality, there are possible in all eight different theories,

that it is a result of both external and internal perception, of internal perception alone, of induction and generalization, of association, custom, habit, of pure intelligence,

of expectation of the constancy of nature, of the law of the conditioned. The principle of causality is, in fact, a consequence, or rather special form, of the Law of the Conditioned; our inability to conceive either the commencement of time or the infinite non-commencement of it, is an inability mentally to create or annihilate it; our inability to conceive space as beginning or ceasing to be, is an inability mentally to create or annihilate it; and, in general, our inability to conceive existence as beginning or ceasing is an inability mentally to create or annihilate it. In this last inability is the explanation of the entire phenomenon of causality. The necessity of the principle of causality is, as appears immediately from the foregoing, a negative necessity, a consequence of "powerlessness; " and the principle may consequently be true or false. (It is, in fact, to a certain extent, false, as is proved by the fact of moral freedom.) Another application of the "Law of the Conditioned" occurs in the use of the notion of substance and phenomenon, or accident. The phenomenon which, conceived in entire isolation, would be unthinkable, because unconditioned, refers us to an underlying substance ; and substance in like manner to phenomenon.

The

The Unconditioned: the Infinite and Absolute. two inconceivable extremes to which the conditioned is the mean are comprehended under the name "unconditioned." The unconditioned, as the extreme of perfect illimitation, or "unconditionally unlimited," is the Infinite; as the opposite extreme, or as the "unconditionally limited," is the "absolute." By the Law of the Conditioned we can know only the conditionally limited, or existence in special modes. From this it follows that we know neither mind nor matter in themselves; nor can we know ultimate being, or God. God by the Law of Excluded Middle must be either the Absolute or the Infinite; but which of these he is, we have (outside revelation) no means of knowing.

Result. Hamilton combines with the doctrines especially characteristic of the Scottish school the negativism

of the Kantian theory of knowledge; and perhaps the most characteristic single feature of his doctrine is the (pseudoKantian?) doctrine of the relativity of knowledge. The influence of Hamilton's teachings has, it is scarcely necessary to remark, been very wide and marked, - marked even where it might not naturally be expected; as, for example, in the case of Spencer. American metaphysics has in the past been largely Hamiltonian. -We may mention here the most important Hamiltonian, Henry Longueville Mansel (1820-1871), Professor at Oxford and Dean of St. Paul's. His chief works are "Prolegomena Logica" (1851), Metaphysics" ("Encyclopædia Britannica," 1857, separately, 1860), "Limits of Religious Thought" (1858), “ Philosophy of the Conditioned." Mansel, however, differs from Hamilton in his doctrine of the Self and his doctrine of Causation. The self is a "fact of consciousness, not an inference from it," is constituted by consciousness. The conditions essential to personal existence are time and free agency. Of causation we know in our consciousness of determining our volitions, and only so; we do not know it as something outside consciousness.

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§ 103.

James Frederick Ferrier1 (1808–1861). Born in Edinburgh, Ferrier was educated at the Edinburgh High School, under a private tutor, and at the universities of Edinburgh, Oxford, and Heidelberg. He was appointed professor of civil history in the University of Edinburgh in 1842, and professor of moral philosophy and political economy at the University of St. Andrews in 1845. He married a daughter of Professor John Wilson ("Christopher North"). His rather premature death has been the cause of deep regret among a large number of admirers of his speculative genius.

Works. Ferrier's principal philosophical work is entitled "Institutes of Metaphysic" (1854; 2d edition, 1856).

1 Ferrier's "Institutes of Metaphysic."