Now, it would be an error to say that science does not, when it can, apply to these various theories its ordinary methods of verification. They are in a different position from inevitable beliefs, which can hardly be verified because the process of verification assumes them. Yet they must not be confounded with ordinary scientific hypotheses, for they are something more and something different. Like these, they are guesses, but they are guesses directed, not by the immediate suggestion of particular experiences (which indeed they sometimes contradict), but by general tendencies which are enduring though sometimes feeble. Those who make them do not attempt the interrogation of Nature wholly free from certain forms of bias. In cross-examining that most stubborn and recalcitrant of witnesses they never hesitate to ply her with leading questions; and, whether this procedure be logically defensible or not, no lover of truth need regret its results.

Readers of M. Bergson’s “Creative Evolution” may remember the picture he draws of the élan vital—the principle of life—forcing its way along different paths of organic evolution, some without issue or promise of progress; others leading on through regions hitherto untraversed to ends remote and unforeseen. The secular movements of science, as I conceive them, somewhat resemble this process, even though it be faintly and at a distance. There is in both a striving towards some imperfectly foreshadowed end; and in both the advance is irregular, tentative, precarious, with many changes of direction, and some reversals. Yet I would not press the parallel over-far or plunge too deeply into metaphor. It is enough to say that as, according to M. Bergson, the course followed by organic evolution cannot be wholly due to Selection, so the course followed by scientific discovery, as I read its history, cannot be wholly due to reasoning and experience. In both cases we seem forced to assume something in the nature of a directing influence, and (as I should add, though perhaps M. Bergson would not) of supramundane design. And if “a Power that makes for truth” be required to justify our scientific faith, we must surely count ourselves as theists.

NOTE

Extracts from a letter from Sir Oliver Lodge on certain passages in this lecture relating to Energy and its transformations.

You say, on page 226, “Energy, we are taught, is of two kinds: kinetic and potential energy—energy in act and energy in possibility.”

So long as emphasis is laid upon the words “we are taught,” I have no objection. People have taught that, though I strongly object to such teaching, because I object to the idea “Energy in possibility” or “possible Energy” of any kind. I teach the identity of Energy in much the same terms as the identity of Matter; not merely the conservation, with the idea that one quantity can disappear and another quantity reappear. It is not another quantity, but the same; though it may have been locked up for any length of time. But then it has not been usually taught so, and I think you are dealing with what is usual.

Again, you say on page 227, “Energy suggests ‘doings’ and ‘happenings.’” No, say I, activity suggests doings and happenings, and activity is Energy in transformation. Energy alone is something stored, like Capital. The earth’s rotational energy, for instance, is stored just as really as, and for a longer time than, the vegetation of the carboniferous epoch.

Lower down you observe that “Force may be exerted though nothing moves.” Certainly it may, when resisted by an equal opposite force. But I fully admit that a lot of nonsense has been talked about the acceleration measure of force, as if it were the only measure, and that some criticism on this procedure is useful. But I should not speak of “latent” force; it is real force you have in mind, or at least real stress—i.e. two equal and opposite forces. It is latent Activity which becomes active when the other factor, viz. Motion, is supplied or allowed—e.g. by the release of a bent bow, or a wound-up spring, or a raised weight.

So it is also with the Energy of a fly-wheel. That, too, is latent Activity until the other factor, viz. Force, is supplied, i.e. when it is employed to overcome resistance, and therefore do work. Otherwise its Motion will be stored to all eternity.

In short, activity, or doing of work, has two factors, Force and Motion. When both are present, work is done; when either is present alone, Energy is stored. Static Energy is the Force factor, with the possibility of a certain range of effectiveness understood; like a head of water, for instance, a certain height above the sea. Kinetic Energy is the Motion factor, with a certain inertia or possibility of Force understood; not Motion alone, but a mass in motion, so that it may be able to overcome resistance.

There is no real reason why one form of Energy should be considered more “actual” or real than another; our eyes appreciate the one form, our muscles could appreciate the other.

In considering cases of Potential Energy, it is wise to realise that our knowledge about Gravitation is altogether too vague to make the case of a raised weight useful. And our knowledge of solid elasticity, though not so insignificant, is small enough to make the case of a bent bow or wound spring not very easy for fundamental contemplation. A case of chemical Energy, like gun-cotton, is in much the same predicament.

But a typical and satisfactory example of Potential Energy is the case of a vessel of compressed air. Here is Energy stagnant enough, and violent enough when released, and one that can be locked up apparently to all eternity, and yet released by the pulling of a trigger. It represents, however, a case of which we know something concerning the internal mechanism; and we have learnt that in this case the force statically exerted on the walls of a vessel is really a kinetic bombardment of the molecules. In other words, we recognise in this case that Potential Energy is ultimately resolvable into Kinetic. It may be so in the other cases. And on Kelvin’s Kinetic Theory of Elasticity, which he showed a tendency in later life to abandon, all strain or stress in Ether may be ultimately due to its ultramicroscopic vortex circulation.

But none of this is yet proven.

The general argument of your lecture deals with the ease with which certain general propositions are accepted as it were intuitively, without real conclusive evidence. I am entirely with you. And the way we feel secure about general laws, when adequate evidence for them is really impossible, has often struck me as remarkable. Even when facts appear to go against them, we question the facts, and find after all that in so doing we have been right.

[PART IV]
SUMMARY AND CONCLUSION

[LECTURE X]
SUMMARY AND CONCLUSION

I

Now that we have reached our closing lecture, those who have followed the course from the beginning may, on looking back, find themselves somewhat bewildered by the variety of subjects which I have asked them to consider. Art, History, Morals, the Theory of Probability, the Logic of Perception, the presuppositions of Science, have all been touched on. Themes that might fill volumes—nay, that have filled volumes—are made the text for an hour’s discourse. Introduced one after the other with breathless rapidity, each for a moment has been shown under the limelight, and then hurried off the stage to make room for its successor. It seems hard to believe that with such diversity of materials there can be continuity of argument. But the critic who would judge the matter fairly must bear in mind the title of the course, and the purpose for which it has been delivered. My desire has been to show that all we think best in human culture, whether associated with beauty, goodness, or knowledge, requires God for its support, that Humanism without Theism loses more than half its value. Though, therefore, the subjects discussed are embarrassing in their variety, no diminution of their number seems possible. The argument would have broken down had I confined myself to a narrower scope—had I, for example, been content to show the importance of Theism for morality, leaving untouched its importance for science and æsthetic. Such a limitation would have shattered the whole design. No doubt there are precedents for such a procedure. Kant, for instance, kept God out of the critique which dealt with ordinary knowledge, while giving Him a place of honour in the critique which dealt with the moral law. But the procedure has always seemed to me singularly artificial, even in a philosophy which is artificial through and through. In any case, such a limitation is quite inconsistent with the scheme of these lectures. This could not be accomplished by setting up a departmental Deity—even were his department the whole province of ethics. Right conduct is much, but it is not all. We not only act, but we know, and we admire; nor could I be quite content with any form of Theism which did not sustain in every essential part the full circle of human interests.