lution and, for the time being, covers appetite and will. But I have no desire to summarize or criticize such an extensive and careful book in the space of a few lines. I merely wish to indicate the important place it occupies and the direction which its philosophy indicates.

I shall not return to Binet's endeavors, of which I have spoken on former occasions at sufficient length, along the line of the relations between body and soul; nor shall I revert to the works of Le Dantec. Neither biologists nor metaphysicians, in short, have succeeded in making us see more clearly into the phenomena of consciousness, intellect and instinct. All one can say is that, in spite of many failures, our researches have resulted in placing us in a truer attitude toward the problems of life and the spirit. And surely this is of itself no slight advantage.

At bottom the problem of cognition remains one of the leading questions of modern philosophy. But our philosophers approach it in a very different way from that of their forerunners, and the problem itself seems to have assumed a different form. Whereas formerly the endeavor was made to investigate the means of cognition and to define its modes and scope, the aim in our day is rather to criticize the results (Poincaré), to estimate the true value of the laws of science and the validity of its hypotheses a sort of expectant attitude that has with some exaggeration been called anti-intellectualism. I would see antiintellectualism most particularly in the mystic theories of the unconscious and of instinct (Bergson) arising out of psychological studies and tending in effect to limit and reduce the rôle of the intellect.

In this chapter I must also mention some exceedingly interesting writers, curious and original minds, such as Jules de Gaultier, A. Chide, Boex-Borel (Le pluralisme). The opportunity to make them better known to my readers may present itself some day.

It is necessary to add that historical studies, dealing with an entire period or with certain philosophers considered separately have likewise not been wanting? Besides the Collection des grands philosophes which is growing rapidly, it may suffice to mention the very considerable work of Joseph Fabre, who conducts us from ancient thought to "modern thought"; that of François Picavet, who covers the Middle Ages; that of H. Delacroix, devoted to the mystics; the Vinci of Duhem, and of Peladan; the Kant of V. Delbos, etc.

I ought likewise to mention the attempts at collective work undertaken by separate sections and commissions in the Institut générale psychologique. Studies have been made with varying success in the psychology of animals (Perrier, Bohn, Hachet-Souplet) and the phenomena of spiritism (the extended report of J. Courtier). Special problems in esthetics have been broached beginning with a study of visual memory in the painter.

This activity is encouraging. I cannot, however, forebear a feeling of sadness at the approaching disappearance of the strong generation to which we owe the magnificent impulse and fine work of the last thirty years. A new generation is at our door that will gather the harvest in its turn. It will no doubt apply itself to testing the results achieved and to revising our provisional conclusions. May it succeed in adding largely to our common store!

LUCIEN ARRÉAT.

PARIS, FRANCE.

THE UNVERIFIABLE HYPOTHESES OF SCI

ENCE.

MOR

ORE and more the conviction grows and spreads, that science is or is to be the light of the world. The one supreme gift of education is or is to be the scientific attitude of mind. The problem of problems, therefore, is to understand, to make lucid, to make conscious, to make transmissible the essentials of scientific thinking.

The bond of harmonious world-life is the scientific habit of mind. How horribly we have been hypnotized by words and out-worn creeds, while even yet eighty percent of us die from causes completely preventable.

The marvelous objective contributions of science flare up on every hand about us. The chemist's coal-tar colors are not more vivid than the lurid light of electricity, now a household fairy with telephone and electric smoothing iron. While the X-rays reveal our very bones and wireless telegraphy pierces the blackest of ocean's tempests, we are unastonished while Sir William Ramsay and Madame Curie debate whether the dream of the alchemists, the transmutation of metals, has come true.

But these gemmed palaces uprising at the rubbing of the Aladdin's lamp of science, looked at only from without, unmastered, lend themselves only too readily to the aid of the false magician, dealer in the magic of words.

Calling Christ scientist was the shrewd appropriation and utilization by Mrs. Eddy of the universally growing conviction of even the densely unscientific that science is the hope of the world. Willingness to try the swallowing

of a cholagogue with so sympathetic a trade mark was actually stimulated by the real wonder-working of true science. Men and women can be charmed with words. Things, much more stubborn, bow only to the sovereignty of one kind of thought, the scientific. What then are the identifying characteristics of this the only lawful prince?

For example, wherein differ these three beliefs, the belief of the Coreans that epileptic fits are demoniacal seizures to be treated by trying to cast out the devils, the Mrs. Eddy contention that there is no sickness and the epileptic fits are only illusions caused by malicious animal magnetism, a suppositious entity relief from which she has actually sought in our law courts, and finally the position of the Japanese army-surgeons that an epileptic fit is a phenomenon produced by an abnormal explosive discharge of nerve force overflowing proper channels, self-limited as the flood from a bursting water tank, not stopped by the exorcising of a demon? An epileptic seizure is often preceded and heralded by a distinctly recognizable aura. Is the one who feels the oncoming stroke, to pray, to telephone for the police, or instantly to snuff up the nose the fumes from an uncorked bottle of nitrite of amyl?

From nothing assumed, nothing can be proved! Every conclusion supposes premises. But even the learned have heretofore not realized that the necessary hypotheses of science are of two distinct kinds. Every one has recognized those hypotheses which are valuable precisely because they are either verifiable or else refutable through definite appeal to the tests furnished by what we have called experience and experiment. However, what we call experience and experiment is not all. No scientist has ever been able to get on without hypotheses. But the essential thing is never to make them unconsciously, and the scientist of the past has here been a sinner.

The epoch-making revelation is that among the scien

tist's necessary assumptions, both conscious and unconscious, are some of a kind hitherto unrecognized, of a genus wholly different from what he thought them, hypotheses wholly and forever indemonstrable, which experience and experiment, however interpreted, are eternally inadequate to prove. Once pointed out, the antithesis, the contrast between these two species of scientific hypotheses is strikingly abrupt. The routine scientist, taken unawares, would be tempted stoutly to deny the scientific importance, yea, the very existence in science, of hypotheses of this newly revealed type. What! a scientific hypothesis by its very nature incapable of proof! Far be it from him! Yet to these unrecognized friends he has owed, he owes all his success. From their stimulus, with their guidance under their protecting wings he has done all his work toward interpreting his experiments, his experience, his world.

Such a hypothesis, yet so long misunderstood, is Euclid's celebrated parallel postulate, familiar in Ludlam's form: Two straight lines which cut one another cannot be both parallel to the same straight line.

How easy this hypothesis! Why not prove it? Almost every man of science throughout the ages did try to prove it.

Says Poincaré: "What vast effort has been wasted in this chimeric hope is truly unimaginable."

At last comes the new step. Says Lobatchevsky: "In the uncertainty whether through a point there is only one straight coplanar with a given straight yet nowhere meeting it, we will assume it may be possible that there are still other straights which do not cut the given straight, though coplanar with it and through the given point."

Here then we have Euclid's hypothesis characterized as a scientific assumption forever indemonstrable and therefore subject to direct, explicit contradiction, subject to replacement by an assumption flatly contradicting it.