and true when it stands in the mind clear and distinct in its own selfevidence and asserts itself as knowledge.

II. The second criterion is the impossibility of thinking the contrary to be true. This is merely the first criterion reversed. The positive knowledge is tested by an effort to reject it and believe the contrary. If it is found impossible, the reality of the knowledge is more clearly disclosed. It is analogous to testing the strength of material, first by a direct strain, then by a transverse.

This test is commonly applied to the universal and self-evident principles which regulate all thought; for example, it is impossible to think of space as discontinuous, or to think of both of two contradictory propositions as simultaneously true. In these cases it is impossible to think the contrary as true in any place or time or under any circumstances or conditions.

The test is equally applicable to knowledge of a particular reality present to consciousness here and now; for example, my knowledge that I feel a pain. In such a case it is possible to think the reality to be unreal at another place and time or under other conditions; but so long as it is present in consciousness I can no more think it to be absent, or unknown or unreal than I can think that a thing may be and not be at the same time. In the knowledge of a primitive and universal principle the impossibility to thought of its contradictory is universal. In the knowledge of a particular fact the impossibility to thought exists only in a particular place and time and under particular conditions. Herbert Spencer states it thus: "In the one instance the antecedents of the conviction are present only on special occasions, while in the other they are present on all occasions. In either case, subject the mind to the required antecedents and no belief save the appropriate one is conceivable. But while in the first case only a single object serves for the antecedent, in the other any object, real or imagined, serves for antecedent.”*

The fact that this second criterion is the converse of the first is important, especially in its application to the primitive beliefs of universal principles which are regulative of all thinking. It implies that these beliefs do not result from intellectual impotence, as Hamilton teaches in respect to the causal judgment, but from positive knowledge. The belief of the principle does not result from impotence to think the contrary, but the impossibility of thinking the contrary results from the self-evident and positive belief. It is not a negation of knowledge arising from incapacity to think, but knowledge so positive that it carries in itself the consciousness that it is impossible to think the

*The Universal Postulate; Westminster Review, Oct. 1853. See also his Psychology, 426–437.

contrary. It therefore gives no basis to the doctrine that God is unknowable, which is inferred from Hamilton's theory of mental impotence.

It must also be noticed that that which is impossible to thought or unthinkable must be distinguished from the inconceivable, whether by the inconceivable is meant the unimaginable, or that which is not conceived in a logical concept or general notion. This distinction is important because it is often urged by agnostics that because God is inconceivable he must be unknowable.

If by the inconceivable is meant the unimaginable, that which cannot be pictured in the imagination, we need not look far to discover that the thinkable and knowable is not restricted to the conceivable. A person blind or deaf from birth knows that there are people who see and hear, that there are light and color and sound. But the blind man cannot picture light and shade and color to his imagination, nor the deaf man sound. Dr. Maudsley says of Kruse, who was completely deaf, that "musical tones seemed to his perception to have much analogy with colors. The sound of a trumpet was yellow to him; that of a drum red; that of the organ green." ""* So it is possible to think of a being endowed with a sixth sense, although it is impossible to imagine what the revelations of the sense would be. I know there is a branch of Mathematics called Quaternions, but I cannot picture its methods to my imagination because I have not used them. The general notion horse is thinkable and knowable; I can denote it by a symbol, spoken or written; but it is not imaginable; if I try to picture it to the imagination I get only a particular horse, of a definite size, color and action. It is idle then to argue that whatevever is inconceivable in the sense of unimaginable is therefore impossible to thought and cannot be known as real.

If by inconceivable is meant that which cannot be formed with other individuals of the same kind into a general notion, it is also evident that what is possible to thought and knowledge is not restricted to the conceivable in this sense; because the knowledge of the individual precedes the knowledge of the general notion; the knowledge of the general notion is conditioned on the knowledge of the individual.

Therefore this second criterion must not be understood as affirming that a belief is true when its contrary is inconceivable, but only that it is true when the mind in its reflex action on its own knowledge, finds it impossible to think its contrary as real or true under the existing conditions; and, in the case of intuitions of primitive and universal principles, finds it impossible to think the contrary true under any

** Physiology and Pathology of the Mind, p. 45.

conditions; finds in fact that the assertion of the contrary would be nonsense, words used without meaning. Thus the common objection of agnostics that God is unknowable because in either or both of these senses he is inconceivable, is seen to be without force.

III. The third criterion of knowledge is its persistence in face of all efforts of reflective thought to disprove it. By the persistence of belief in face of objection, ratiocination, and all reflective thought upon it, the mind ascertains that it is impossible to think the contrary and that the belief stands impregnable in its clearness and evidence as knowledge.

This persistence may appear in two ways. It may appear as persistence of intellectual assent notwithstanding all argument against it. It may also appear as persistence of spontaneous belief practically controlling action, even when, as the result of speculative thinking, it is conceded that the belief is untenable and its contrary is affirmed as true. Thus the idealist continues to be practically controlled by belief in the real existence of bodies, and the materialist by the belief that he is a free and responsible agent.

In applying this principle we may refer to the persistence of knowledge in our own individual experience, and also in the experience of mankind. We are not, indeed, to decide between the true and the false by the votes of a majority. But in investigating the experience of mankind we are not seeking to decide any question by votes, but simply to ascertain what are the persistent, essential and primitive elements of human intelligence. There is difficulty here in ascertaining the facts; for the multitude of men have given us no information as to their conscious experience. But from observation, literature and history we have attained a large knowledge of the characteristics of humanity, and the researches of anthropologists are continually increasing it. From these sources it is possible to ascertain what sentiments and beliefs are found persisting in all the experience of man And if we find knowledge either of a particular reality or of a universal principle which has been an element in all human experience, has consciously or unconsciously controlled all human thinking, and has persisted through all the changing conditions and progress of man, this persistence we accept as a mark of primitive, self-evident knowledge springing directly from the human constitution and revealing the external environment common to all mankind.

It may be objected that illusions of sense persist through all the experience of mankind; to the vision of man the firmament is always an azure dome, the heavenly bodies move in it, parallel lines seem to converge; and it is objected that these persistent illusions make the criterion useless. I answer that all that persists in these so-called illu

sions is true and real. In vision, for example, the man sees the external objects precisely as the eye presents them. In the seeming convergence of parallel rails his eye reports truly the physical reality of the lessening of the angle of vision with increasing distance. His intellect interprets the sensation. If there is any error it is not in the sensation but in his interpretation of it. And this error does not persist. The belief that the heavenly bodies move around the earth or that the firmament is a solid dome, has not persisted.

IV. The fourth criterion of primitive knowledge is the consistency of itself and its necessary outcome with all knowledge. This criterion is of great practical importance in scientific and all other reflective thought. It has recently been said, "Internal consistency and harmony was the only test of truth known to antique thought; and it supplemented the appeal to actual authority characteristic of mediæval thought." This is an example of a common style of remark depreciating ancient and especially medieval thought. Such remarks grossly misrepresent the facts. And the depreciation of this criterion as of little value is contradicted by the continual use of it in modern thought. The verification on which science insists so strenuously as necessary to establish an hypothesis is nothing but ascertaining the consistency of a conclusion of reflective thought with the results of observation. It is true, the mere self-consistency of a conception does not prove that it is a conception of reality. I may form a consistent theory of the government of fairies by Oberon and Titania. It is consistent with all known facts that beyond Neptune there may be a planet belonging to the solar system. These are only creations of imagination or conjectural possibilities, and do not present themselves in consciousness as knowledge. Mere consistency of thought cannot originate knowledge, but it may test it. Man has varied powers or faculties, and knowledge obtained through one faculty or from one sphere of investigation must be consistent with knowledge obtained from every other. This consistency is a criterion of knowledge. What I perceive by the eye I test by the hand. The correctness of an arithmetical division is tested by multiplication. If a necessary inference from a supposed principle is false, it compels us to doubt either the truth of the principle or the correctness of our reasoning from it. Speculative conclusions must be tested by observed facts. If an observed fact contradicts an accepted conclusion of science, the observation must be repeated and corrected or the scientific conclusion must be modified. The whole process of verification is an ascertaining of the consistency or inconsistency of the results attained by one intellectual power or process and from one sphere of inquiry with those atThe Value of Life; A Reply to Mallock, p. 73.

tained from others. And so far as from all we obtain successively the same results, our knowledge is tested and confirmed.

The same criterion may be applied in testing what is primitive knowledge. If the intuitions of reason contradict each other they are proved false and at the same time reason itself is proved untrustworthy. If what seems to be primitive knowledge and its necessary outcome is inconsistent with itself or with other knowledge it is not primitive knowledge.

But the criterion is not merely negative. If primitive knowledge is found to be in harmony with experience, if the first principles which regulate thought do not lead us in our reasonings to error and contradiction but to conclusions which all our powers in concurrence acknowledge as truth, if what we in our philosophy hold to be primitive knowledge conditioning experience, is in harmony with our actual experience, then we may properly say that it is continually verified by experience. It is consistent with itself and with all knowledge.

It must be observed respecting the four criteria, that the mind does not consciously appeal to them in the primitive acts of knowing, but only in reflection on its own acts and in answer to the question whether knowledge is real. If then it is seen that the knowledge stands out clear and distinct in its own self-evidence, that it is impossible to think the contrary as real, that the belief persists in spontaneously regulating thought and action in the face of all speculative objections, and that it not only does not contradict any other knowledge, but is accordant with all our thinking and experience, it is accepted as real knowledge. If not, knowledge is impossible.

? 8. Knowing, Feeling and Willing.

I. Knowing, feeling and willing are distinct but not separate. They are not separated in human experience. In every feeling there must be knowledge or belief. Every act of will involves feeling which is its motive, and knowledge, which is the light in which the determination is made and without which freedom of determination is impossible. And knowledge remains but nascent and cannot be apprehended in its complete significance until it reveals itself in feeling and discharges itself in voluntary action. The Speculative Reason cannot find the content and significance of its own necessary ideas nor solve its own necessary problems until it becomes the Practical Reason.

Dean Swift compares the man of culture to the bee, which "visits all the flowers of the field and of the garden and by an universal search, much study and distinction of things, brings home honey and thus furnishing mankind with the two noblest things,

wax.