Moreover, we are bound to recognize the great value of that impartial and unprejudiced collection of facts upon which this early empiricism laid so much stress. And yet it is imperative to add that the mind cannot collect facts methodically unless it also selects them. Not only is there a natural tendency to observe in the light and under the selective guidance of a thought, but, further, it is essential to the interests of scientific progress that the mind should go to meet the facts armed with ideas. It is not enough to be faithful to fact. Science must be faithful to its own facts, to the facts relevant to its own ideas. What Induction needs as its guiding principle is not a vague Fidelity to Fact, but Fidelity to Relevant Fact.*

Speaking from the standpoint of a developed Science, it follows (1) that, prior to any collecting, the mind should know towards what end and for what purpose the collection is to be made; and (2) that during the collection of material it must be ready to seize on any indication of a law embodied in the material, to make a hypothesis of it, and to test it either by experiment, or, if experiment is impossible, by further collection of material.

...

In illustration of the form which the Baconian method would thus assume, we quote the following from Darwin's 'Autobiography': 'After my return to England, it appeared to me that, by following the example of Lyell in Geology, and by collecting all facts which bore in any way on the variation of animals and plants under domestication and nature, some light might perhaps be thrown on the whole subject. I worked on true Baconian principles, and without any theory collected facts on a wholesale scale, more especially with respect to domesticated productions, by printed enquiries, by conversation with skilful breeders and gardeners, and by extensive reading.... I soon perceived that selection was the keystone of man's success in making useful races of animals and plants. But how selection could be applied to organisms living in a state of nature remained for some time a mystery to me. In October, 1838-that is, fifteen months after I had begun my systematic enquiry-I happened to read for amusement Malthus on Population, and being well prepared to appreciate the struggle for existence which everywhere goes on from long-continued observation of the habits of animals and plants, it at once struck me that, under these circumstances, favourable variations would tend to be preserved, and unfavourable ones to be destroyed. The result of this would be the formation of new species. Here, then, I had at last got a theory by which to work.'†

This adoption of the Baconian method seems to have come * Vide Introduction, pp.1-8; also the concluding chapter on the Inductive Postulate.

† 'Charles Darwin: his Life told in an Autobiographical Chapter, and in a Selected Series of his Published Letters. Edited by his son, Francis Darwin,' ch. ii., pp. 39, 40.

naturally to Darwin through his being a born 'collector,' as witness the following extracts:

At eight years of age 'my taste for natural history, and more especially for collecting, was well-developed. I tried to make out the names of plants, and collected all sorts of things-shells, seals, franks, coins, and minerals. The passion for collecting which leads a man to be a systematic naturalist, a virtuoso, or a miser was very strong in me, and was clearly innate, as none of my sisters or brother ever had this taste.'*

'No pursuit at Cambridge was followed with nearly so much eagerness, or gave me so much pleasure, as collecting beetles.'† During the voyage of the Beagle ' another of my occupations was collecting animals of all classses, briefly describing and roughly dissecting many of the marine ones.'†

It is therefore not surprising to read the following: 'My mind seems to have become [at seventy-two years of age] a kind of machine for grinding general laws out of large collections of facts.'

On the other hand, this Baconian method was not adopted to the exclusion of the 'Newtonian.' 'I have steadily endeavoured,' he says, 'to keep my mind free, so as to give up any hypothesis, however much beloved (and I cannot resist forming one on every subject) as soon as facts are shown to be opposed to it. Indeed, I have had no choice but to act in this manner, for, with the exception of the Coral Reefs, I cannot remember a single first-formed hypothesis which had not after a time to be given up or greatly modified.' With this we may compare a passage from his son's 'Reminiscences.' Speaking of his father, the writer remarks :

'He often said that no one could be a good observer unless he was an active theorizer. This brings me back to what I said about his instinct for arresting exceptions; it was as though he were charged with theorizing power ready to flow into any channel on the slightest disturbance, so that no fact, however small, could avoid releasing a stream of theory, and thus the fact became magnified into importance.'§

We conclude, then, that, whatever stress we lay on the value of collecting instances with open mind and letting the facts speak for themselves, we cannot dispense with Hypothesis. Hypothesis is needed to give meaning to Fact.

The attitude taken by the radical empiricists of the early Inductive period may be explained, though not, indeed, justified, as a reaction against the apotheosis of dogma in the days of Scholasticism. The principle of investigation here was not fidelity to fact, but

* 'Charles Darwin: his Life told in an Autobiographical Chapter, and in a Selected Series of his Published Letters. Edited by his son, Francis Darwin,' ch. ii., p. 6.

† Ibid., p. 20.

‡ Ibid., p. 52.

§ 'Life and Letters of Charles Darwin, edited by his son, Francis Darwin,' vol. i., ch. iii., p. 149.

loyalty to dogma. The dicta of Aristotle and of Church Theology were treated as beyond the reach of criticism, and the aim of Science was construed as that of reconciling Nature with Dogma, and of proving herself the dutiful handmaid of Philosophy and Theology.

Thus the discovery of Copernicus was opposed by reasoning such as the following:

'Theology teaches that the sun was made to give light to the earth.

'Now, when we wish to light our houses, we do not move the house about the torch. On the contrary, we move the torch about the house.

'Therefore it is the sun that moves about the earth, not the earth about the sun.'

An old scholastic professor, when his pupil one day brought to his notice Galileo's discovery of sun-spots, made the following characteristic remark:

'My friend, I have read Aristotle twice from beginning to end, and I know that there cannot be spots on the sun. Just wipe your glasses a little more carefully. If the spots are not in the telescope itself, they must be in your own eyes.'*

B. THE ESSENTIALS OF INDUCTION.†

(1) Principle and Method.

The principle upon which the early empiricism proceedednamely, that of Fidelity to Fact-was sound at heart, and, as applied by the empiricists, contained implicitly the tendencies requisite to its own correction. Busied as they were with fact, they were equally concerned about Method; and fidelity to fact implied, as its precondition, fidelity to the method, instrument, or organon, through which the facts were to be approached and studied. For them, fidelity to fact really meant fidelity to fact along the lines of pure inductive method. Relevancy to scientific purpose, though not explicitly recognized, was still unquestionably implied in their whole attitude towards Nature. Thus the task of the later Induction has not been that of substituting a fresh principle and a fresh method, but of reconstructing both. Fidelity to Relevant Fact may be accepted as an adequate principle for modern inductive research, but it is simply a specification of the vaguer principle of Fidelity to Fact. Still, the specification is of the first importance. In explicitly introducing, through the use of the term 'relevant,' a reference to scientific purpose, it draws attention to the fundamental truth that fact out of relation to idea is meaningless, and that it is only in so far as fact is relevant to idea that idea can be true to fact.

Closely connected with this fundamental improvement in the conception of the principle, we have an equally radical improvement in the method of its application. The method was improved by giving Hypothesis a central place in inductive procedure, whilst the empirical ideal was adequately guaranteed by insistence on Verification. Through the Verification-test subjective prejudices are warded off quite as effectively as though they had never been allowed a chance of expressing themselves, and Science is the gainer by enlisting the powerful assistance of the scientific Imagination. The due recognition that the limitations characteristic of the earlier empirical method were not only uncalled for in the interests of fact, but prejudicial to such interests, coincides with the first clear perception of what we really mean by that 'Fidelity to Relevant Fact' which is the fundamental guiding idea of Scientific Explanation.

Nor must it be supposed that this jealous care for Fact implies any opposition to the interests of System. On the contrary, it is precisely the loyalty to Fact that explains the organization of Science into System. A perpetual willingness to be lessoned by fact is, indeed, the characteristic of all Science that has ever succeeded in systematizing itself. And this is very significant; for it shows that the fact which Science calls Nature is itself systematically structured, and that the systematic character of successful Science is forced upon it by the very nature of the facts it endeavours to interpret. And that the facts can only be interpreted systematically means just this that Nature, being itself systematic, can only be understood in the light of a system. To interpret facts is to systematize them.

The Principle of Induction, then, cannot be understood in any sense that implies disparagement of System. To be controlled by the facts-the relevant facts-just means to be shaped into systematic coherency through the essential coherency of fact itself. In refusing to go beyond the evidence, the scientific spirit is assimilating the principles of an objective order, making them its own, and approximating more and more to the ideal of systematic unity in interpretation.

And yet it would be misleading to say that Science aims at its own systematization. For the true lesson of Science is that systematic coherency can be gained only indirectly. To aim directly at being systematically coherent is to forfeit the true objective system to which Fact is the one and only key, and to win a partial systematization that is hopelessly subjective, and doomed on that account to eventual barrenness.

Hence the supremacy, for Science, of Fact over System.* The true interest of System is secured by subordinating the desire for systematic coherency to the determination to be at all costs faithful to the facts. Fact dominates System because it is, in its true nature, itself the ideal and standard system.

(2) Hypothesis.

We have seen that, in the application of the new Inductive Method, Hypothesis is a central and indispensable factor. It is the essential medium of contact between the scientific system, which is being applied to the explanation of facts, and the facts to which it is being applied. As consistent with the system of which it has been provisionally enrolled a corporate member, a hypothesis belongs to the system. As the direct agency through which the facts are to be explained, it belongs to the facts. Consistency is required of it from the one point of view; truth is required of it from the other.

The hypothesis is not artificially grafted on to the scientific system in question, but is its product, and presupposes it. The law of gravitation, as conceived by physical Science, presupposes a whole theory of dynamics, and in the formulation of it the requirements of this theory of dynamics were all along kept rigidly in view (cf. Newton's treatment of Descartes' 'Theory of Vortices'). It is the scientific system which gives to the hypothesis its explanatory resources, its deductive vitality. Consider how forlorn and resourceless a theological or philosophical hypothesis is when grafted on to a scientific system, and vice versa.

(3) Deductive Inference.

We may distinguish three main functions of deductive inference :

1. The development of a hypothesis.

2. The application of a hypothesis.

3. The proof of a proposition from axiomatic premisses.

* We do not say 'of Fact over Idea,' for Fact is nothing out of relation to Idea. Our point is simply that Science attaches primary importance to being true to Nature in so far as Nature is relevant to its inductive idea. Its own organization as Science is a subsidiary matter.