This a priori dogmatism imposes itself as a necessity on materialism, and destroys the experimental character which it loves. The learned, devoted to the worship of positive science, are obliged to admit this, and M. Caro cites, on this point, the precious admission of an illustrious savant, M. Virchow, whom the materialists claim as one of themselves. "No one, after all," says M. Virchow, "knows what was before what is. … Science has nothing but the world which exists. … Materialism is a tendency to explain all that exists, or has been created, by the properties of matter. Materialism goes beyond experience; it makes itself a system. But systems are more the result of speculation than of experience. They prove in us a certain want of perfection which speculation alone can satisfy; for all knowledge which is the result of experience is incomplete and defective."
It is not a metaphysician who speaks thus; it is a savant, who, in Germany, ranks at the head of experimental biology, who leans to materialism, and admits, nevertheless, that materialism has no other root than an undemonstrable a priori; consequently M. Caro has the right with ironical good sense to draw these conclusions: "Until materialism leaves that vicious circle which logic traces around its fundamental conception; until it succeeds in proving experimentally that that which is has always been as it is in the actual form of the recognized order of phenomena; so long as it cannot strip those questions of their essentially transcendental character, and subject its negative solutions to a verification of which the idea alone is contradictory; until then—and we have good reason to think that period far distant—materialism will keep the common condition of every demonstration that cannot be verified. It may reason, after a fashion, on the impossibility of conceiving a beginning to the system of things, to the existence of matter and its properties, but it will prove nothing experimentally, which is, according to its principles, the only way of proving anything; it will speculate, which is very humiliating for those who despise speculation; it will recommence a system of metaphysics, which is the greatest disgrace for those who profess to despise metaphysics. We are continually reproached with the a priori character of our solutions concerning first causes. Materialism must necessarily accept its share of the blame, no matter how full it may be of illusions regarding its scientific bearing and value, no matter how intoxicated with the conquest of positive science with which it essays in vain to identify its fortune and right."
We have just seen, with M. Caro, whether materialism can call itself the faithful representation and direct product of the experimental method. M. Janet, in one of those little volumes, Le Matérialisme Contemporain, destined to a happy popularity, and in which high reason and good science are made clear and simple to convince better, shows us what is the value of the solutions proposed, even nowadays, by materialism. The two works of MM. Caro and Janet thus complete each other: the one discusses the question of methods, and judges materialism in face of its own work, and systematic development; the other asks it, after its labors, whither the method it has used has led it, and interrogates it on those questions of origin and end which it treats and so boldly resolves.
III.
Materialism has two grand problems to solve: matter and life. No one would hesitate to say that the first of these is within its scope, and the solution easy for it. What should be better able to teach us what matter is than a system which recognizes nothing but matter? Has matter in itself the reason of its existence, the reason especially of the motion which impels and moves it, causes all its changes, and what seems now to be the only origin of all its properties and of all its manifestations? M. Janet, in a chapter particularly original, La Matière et le Mouvement, demonstrates that matter cannot present the conditions of absolute existence which are necessary to it if we admit nothing above it. Materialism, instead of arriving at a substantial and freed matter, has nothing ever before it but an intangible unknown. To find nothing for basis of its affirmations but the unknown, and pretend on this basis to build a philosophical belief, seat the destinies of humanity on the unknown, is an outrage on reason and good sense. What a chimerical enterprise! "What would signify, I ask," writes M. Janet, "the pretensions of materialism in a system in which one would be obliged to confess that matter is reduced to a principle absolutely unknown? Is it not the same to say that matter is the principle of all things, in this hypothesis; and to assert that x, that is, any unknown quantity, is the principle of all things? It would be as if one should say, 'I do not know what is the principle of things.' What a luminous materialism this is!" But let us leave pure matter aside; although it touches and bounds us on every side, it does not seem to contain the peculiar secret of our origins and destinies. Let us go further and interrogate materialism regarding life and living beings, among which we are counted, and the study of which penetrates so deeply into our own life.
Materialism pretends to explain the mysterious origin and first appearance of life; and imagines that it can establish by experience the conditions and cause of the formation of simple and rudimentary organizations. The theory of spontaneous generation answers these experimental conditions, and is the proximate and sufficient cause of the existence of life. Having obtained those primary organic forms, materialism explains the immense multiplicity of living species by the gradual transformation of the rudimentary organic forms, produced by spontaneous generation; a transformation effected by natural conditions. Spontaneous generation is consequently a primary thesis of materialism.
"We see," says Lucretius, "living worms come out of fetid matter when, having been moistened by the rain, it has reached a sufficient degree of putrefaction. The elements put in motion and into new relations produce animals." The whole theory and all the errors of spontaneous generation are contained in these phrases.
The progress of the natural sciences gradually extinguished the belief in spontaneous generation. In proportion as science studied this pretended generation it disappeared, and ancestral generation became evident. M. Pouchet has reawakened the discussion of the question by transporting it into the study of those lives of only an instant in duration, which the immense multitude of animalcula presents. Those lives, still so little known and so hard to observe in their rapid evolution, offered a favorable field for confusion, premature assertion, and arbitrary systems. To affirm their spontaneous generation, or demonstrate their generation by germs detached from infinitely small organizations in their complete development, was a task equally obscure and apparently impenetrable to experimentation. The one theory was opposed to all the known laws of life, while the other was in conformity with those laws. It seemed, therefore, that unless demonstrated by all the force of evidence, the spontaneous generation of animalcula should find no legitimate place in science. But not only was evidence always wanting, but thanks to the wonderful ability displayed by M. Pasteur; thanks to the beauty, precision, clearness, and variety of the experiments performed by him; thanks to the penetrating sagacity with which he has exposed the defects of the contrary experiments of M. Pouchet and M. Jolly, all the evidence is in favor of ancestral generation; and the Academy of Science, so prudent and ordinarily so reserved in its judgments, has not hesitated to pronounce openly in this sense. Let us hear the eminent M. Cl. Bernard, judging spontaneous generation; even that which, not daring to maintain the complete generation of the being, sought refuge in the spontaneous generation of the ovulum or germ, which being evolved produced the entire being:
"That generation," says M. Cl. Bernard, "which governs the organic creation of living beings has been justly regarded as the most mysterious function of physiology. It has been always observed that there is a filiation among living beings, and that the greatest number of them proceed visibly from parents. Nevertheless there are cases in which this filiation has not been apparent, and then some have admitted spontaneous generation, that is, production without parentage. This question, already very old, has been investigated in recent times and subjected to new study. In France, many savants have rejected the theory of spontaneous generation, particularly M. Pouchet, who defended the theory of spontaneous ovulation. M. Pouchet wished to prove that there was no spontaneous generation of the adult being, but of its egg or germ. This view seems to me altogether inadmissible even as a hypothesis. I consider, in fact, that the egg represents a sort of organic formula, which resumes the evolutive conditions of a being determined by the fact that it proceeds from the egg. The egg is egg only because it possesses a virtuality which has been given to it by one or several anterior evolutions, the remembrance of which it in some sort preserves. It is this original direction, which is only a parentage more or less remote, which I regard as being incapable of spontaneous manifestation. We must have necessarily a hereditary influence. I cannot conceive that a cell formed spontaneously and without ancestry can have an evolution, since it has had no prior state. Whatever may be thought of the hypothesis, the experiment on which the proofs of spontaneous generation rested were for the most part defective. M. Pasteur has the merit of having cleared up the problem of spontaneous generation, by reducing the experiments to their just value and arranging them according to science. He has proved that the air was the vehicle of a multitude of germs of living beings, and he has shown that it was necessary before all to reduce the argument to precise and well-formed observations.