New pathways in science / by Sir Arthur Eddington.

  • Eddington, Arthur Stanley, Sir, 1882-1944.
Date:
1935
Catalogue details

Licence: In copyright

Credit: New pathways in science / by Sir Arthur Eddington. Source: Wellcome Collection.

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    hypotliesis a chemist would never know until after his experiment the composition of the substance he had been handhng, so that the result of every experiment must be unforeseen. Must he then admit that the science of chemistry is chaotic? A man of resource would override so trifling an obstacle. If he were discreet enough never to say beforehand what his experiment was going to demonstrate, he might give edifying lectures on the uniformity of Nature. He puts a hghted match in a cylinder of gas and the gas bums— “There you see that hydrogen is inflammable”. Or the match goes out—“That proves that nitrogen does not sup¬ port combustion”. Or the match bums more brightly— “Oxygen feeds combustion”. “How do you know it was oxygen?” “By retrospective inference from the observation that the match bums more brightly.” And so the experi¬ menter passes from cylinder to cylinder, and the match does now one thing and now another, thereby beautifully demon¬ strating the imiformity of Nature and the determinism of chemical law! If by retrospective inference we infer causal characters at an earUer date and then say that those characters invariably produce at a future date the manifestations from which we made the inference, we are working in a vicious circle. The coimection is not causation but definition, and we are not prophets but tautologists. We must not mix up the genuine achievements of scientific prediction with this kind of charlatanry, nor the observed uniformities of Nature with those so easily invented by our imaginary lecturer. If we are to avoid vicious circles we must refuse to recognise purely retrospective characteristics—those which arc never found as existing but always as having existed. If they do not manifest themselves until the moment that they cease to exist they can never be used for prediction except by those who prophesy after the event. Chemical constitution is not one of these retrospective