These extreme, but logically deduced consequences, are part of the whole of Comte’s religious conceptions, that is to say of a distant ideal. They must not blind us to the profundity of his philosophical considerations on astronomy. His reflections upon the relation between the ideas of the world and of the universe correspond, from the positive point of view, to the first antinomy of the transcendental Dialectics in the Critique de la raison pure. Can we ever be more fully conscious of the relativity of our knowledge, that when we see that what we know of celestial phenomena is admirably precise so long as the solar system is concerned, but is reduced to almost nothing if we look beyond it?
Our world will perish, and its disappearance like its existence, will perhaps be an imperceptible incident. By the continued resistance of the general milieu, says Comte, in the end our world must be re-united to the solar mass from which it came, until, in the immensity of future ages, a fresh dilatation of this mass shall organise a new world in the same manner, destined to repeat more or less completely the former cycle. Moreover, all these immense alternatives of destruction and of renewal have to be accomplished without influencing in any way the more general phenomena due to solar interaction; so that the great revolutions in our world would only be secondary and, so to speak, local events, in relation to transformations of a really universal character.[132]
This outlook into the “immensity” of space and of duration suffices to show that Comte was not a prisoner in the little solar fatherland in which he seems to seclude himself. It may be that for moral and religious reasons he will not allow himself to go beyond it. But, like Pascal, he well knows that he inhabits “a little out of the way district of nature.”
[CHAPTER III.]
THE SCIENCES OF THE INORGANIC WORLD
If we do not separate chemistry from physics, their common object is the knowledge of the laws of the inorganic world. In this way they are clearly distinguished on one hand from astronomy which we may consider as an “emanation from mathematical science,” and on the other hand from biology. The distinction between physics and chemistry presents a greater difficulty. Nevertheless this distinction must be maintained, since the physical phenomena are more “general,” and the chemical phenomena more “special,” that is to say, the latter depend upon the former, without this dependence being for the most part reciprocal. Even if some day we succeeded in establishing that chemical phenomena are in reality physical, the distinction would none the less subsist, in this sense, that in a fact termed chemical, there is always something more than in a fact which is simply physical, namely, the characteristic alteration which the molecular composition of bodies undergoes, and which consequently affects the totality of their properties.[133]
To speak only of physics in the first place, this science presents different characteristics from those of astronomy. The speculative perfection of a science is measured by two correlative although distinct considerations, by the more or less complete co-ordination of the laws, and by the more or less accurate prevision of facts. Now, under one aspect or the other, even supposing that physics should make very important progress, it will always remain very much behind astronomy. Indeed, the celestial science presents an almost perfect unity; physics, on the contrary, is composed of several branches which are almost isolated from one another, and each one taken by itself cannot even reduce all its laws to a more general law. And, as to the second point, while a very small number of direct observations allows of rational and exact prevision of the whole of the celestial phenomena, physics only renders possible predictions which are generally founded upon experience at once immediate and within easy reach. Undoubtedly some parts of physics allow of the use of mathematical analysis (we shall see presently under what conditions). Nevertheless, the part played by experience is infinitely greater in physics than in astronomy. So it is in the former science that we first meet with the inductive method, which is afterwards used and developed in the other positive sciences. Although deduction continues to fulfil an important part, it already ceases to predominate here, because, says Comte, in it the institution of true principles begins to become more troublesome than the development of accurate consequences.[134]
The inductive method implies these essential processes; 1∘ observation properly so called, that is to say the direct examination of the phenomenon such as it appears naturally: 2∘ experimenting, which is usually defined as the examination of the phenomenon more or less modified by artificial circumstances instituted by us in order to study it better; 3∘ comparison, that is to say the gradual consideration of a succession of analogous cases, in which the phenomenon becomes more and more simple. Of these three processes astronomy only makes use of the first. Physics cannot use the third which is reserved for biology; but it avails itself of the first and institutes the second. This is a fresh confirmation of the law established by Comte: to the complexity and increasing difficulty of the sciences, corresponds an increasing development of the processes of the positive method applicable to them.
Research by way of experiment, which is impossible in Astronomy, appears in Physics. It is therefore here where it originates that we must study it. It is also here that it is most successful, and gives the greatest number of results. Indeed, to experiment successfully we must be able to compare two cases “which present no other difference direct or indirect, than that which relates to the course of the phenomenon under analysis.”[135] By experimenting, Comte here clearly designates what John Stuart Mill will call the method of difference, that is to say the most powerful of his methods for the investigation of phenomena.
Now, experimenting, so understood, is extremely difficult when very complicated phenomena are concerned. In physiology, for instance, the experiments must be combined in such a way as to maintain the subjects in the living state, and even, as far as possible, in the normal state. But any modification of one part of the organism immediately affects the other parts. The living being reacts instantly, and adapts itself as best it can to the new conditions in which it has been placed by the experimentalist. We can therefore hardly ever establish in physiology what is so easily obtained in physics: two cases exactly similar in all respects, except in the one which we want to analyse. In chemistry, it is true, experimenting would seem to be even easier than in physics, since in it, as a rule, we merely consider facts resulting from circumstances which are produced by man’s intervention. But this is to mistake the nature of the experimental method. The essence of this process does not consist in man’s institution of the circumstances surrounding the phenomena; it lies in the “freest possible choice of the case best suited to show the law of the phenomenon,” whether this case be, moreover, natural or artificial. Now, this choice is nearly always easier in physics than in chemistry. For the chemical phenomena more complex in themselves, in general can only be brought about by the co-operation of a great number of different influences; for this reason in chemistry, it is more difficult to modify the circumstances under which phenomena are produced, and still more difficult to isolate as completely as in physics the various conditions by which phenomena are determined.