Die Gleichförmigkeit der Natur – The Principle of the Uniformity of Nature

Das Kausalgesetz, wonach jedes Ereignis eine Ursache hat, und dabei gilt: gleiche Ursache gleiche Wirkung, und das Induktionsprinzip, mit dem von einzelnen Beobachtungen verallgemeinert wird, wurden von David Hume in Frage gestellt. Matters of fact, which are the second objects of human reason, are not ascertained in the same manner; nor is our evidence of their truth, however great, of a like nature with the foregoing. The contrary of every matter of fact is still possible; because it can never imply a contradiction, and is conceived by the mind with the same facility and distinctness, as if ever so conformable to reality. That the sun will not rise tomorrow is no less intelligible a proposition, and implies no more contradiction than the affirmation, that it will rise. David Hume: An Enquiry Concerning Human Understanding, IV. Sceptical Doubts concerning the Operations of the Understanding - Part I , 21 "For all inferences from experience suppose, as their foundation, that the future will resemble the past, and that similar powers will be conjoined with similar sensible qualities. If there be any suspicion that the course of nature may change, and that the past may be no rule for the future, all experience becomes useless, and can give rise to no inference or conclusion. It is impossible, therefore, that any arguments from experience can prove this resemblance of the past to the future, since all these arguments are founded on the supposition of that resemblance." Hume: An Enquiry Concerning Human Understanding - Chapter on Cause and Effect.Part II. We may observe in human nature a principle which, if strictly examined, will be found to diminish extremely the assurance, which we might, from human testimony, have, in any kind of prodigy. The maxim, by which we commonly conduct ourselves in our reasonings, is, that the objects, of which we have no experience, resemble those, of which we have; that what we have found to be most usual is always most probable; and that where there is an opposition of arguments, we ought to give the preference to such as are founded on the greatest number of past observations. Hume: An Enquiry Concerning Human Understanding, X. Of Miracles - Part II , 93 [The] principle,that instances, of which we have had no experience, must resemble those, of which we have had experience, and that the course of nature continues always uniformly the same. Hume: A Treatise of Human Nature 1.3.6 First we may observe, that the supposition, that the future resembles the past, is not founded on arguments of any kind, but is derived entirely from habit, by which we are determined to expect the future the same train of objects, to which we have been accustomed. Hume: A Treatise of Human Nature – Sect. XII. Of the Probability of Causes Whether the future will resemble the past is a contingent matter of fact. The supposition that the future resembles the past, is not founded on arguments of any kind, but is derived entirely from habit. (David Hume, 1737) Hume: Enquiries Concerning The Human Understanding and Concerning The Principles of Morals, 1737 Dem Kausalgesetz und dem Induktionsprinzip liegt als Annahme die Gleichförmigkeit der Natur zugrunde. Dieses allgemeinere Prinzip der Gleichförmigkeit der Natur sagt, daß die Naturgesetze universell gelten, sowohl räumlich als auch zeitlich und es läßt erwarten, daß beobachtete Phänomene sich auch künftig so ereignen werden wie bisher. Dieses Prinzip setzt die Induktion schon voraus, ist also zirkulär. Das Prinzip der Gleichförmigkeit der Natur tritt in verschiedenen Ausprägungen auf. Die Gleichförmigkeit der Natur lässt sich aber empirisch nicht rechtfertigen. Nach Hume ist es eine Gewöhnung des Menschen, der dazu neigt eine Kausalität anzunehmen und der erwartet, das zukünftige Ereignisse den bereits beobachteten gleich oder zumindest ähnlich sind ("the future will resemble the past"). John Stuart Mill und Immanuel Kant griffen die Frage nach der Rechtfertigung dieses Prinzips wieder auf. In einem transzendentalen Argument zeigte Kant, daß das Prinzip der Gleichförmigkeit der Natur und der Kausalität notwendig ist, damit Erfahrung überhaupt ermöglicht wird. Bertrand Russell gab das folgende schlagende Beispiel gegen die Induktion. "We know that all these rather crude expectations of uniformity are liable to be misleading. The man who has fed the chicken every day throughout its life at last wrings its neck instead, showing that more refined views as to the uniformity of nature would have been useful to the chicken." Bertrand Russell: The Problems of Philosophy VI On Induction Karl Popper stimmt Hume zu: die Induktion lässt sich nicht rechtfertigen. Er geht einen Schritt weiter: die Wissenschaft braucht die Induktion nicht.

Bertrand Russell “It has been argued that we have reason to know that the future will resemble the past, because what was the future has constantly become the past, and has always been found to resemble the past, so that we really have experience of the future, namely of times which were formerly future, which we may call past futures. But such an argument really begs the very question at issue. We have experience of past futures, but not of future futures, and the question is: Will future futures resemble past futures? This question is not to be answered by an argument which starts from past futures alone. We have therefore still to seek for some principle which shall enable us to know that the future will follow the same laws as the past.” Bertrand Russell: Problems of Philosophy, Chapter VI On Induction (S. 35-36) – Rezension Russell erweitert also die Frage "Will the future resemble the past?" zu: "Will future futures resemble past futures?" (siehe auch Rowe 1976)

Das Prinzip der Gleichförmigkeit der Natur ist nicht a priori, da es nicht unabhängig von der Erfahrung gerechtfertigt werden kann. Aber es kann – wie die obigen zitierten Argumente zeigen – auch nicht empirisch gerechtfertigt werden: man gerät in einen Zirkel der Argumentation oder man würde eine unendliche Zahl von Beobachtungen benötigen.

Links

Hume's fork

The Principle of Uniformity of Nature

Literatur

Howson, Colin (2001): "28. Induction and the Uniformity of Nature". In: W. H. Newton-Smith, Hg.: A Companion to the Philosophy of Science. Blackwell, 2001.

Rowe, William L. (1976): "Skepticism and Beliefs about the Future". Philosophical Studies 30, S. 105-109.

Salmon, Wesley C. (1953): "The Uniformity of Nature". Philosophy and Phenomenological Research 14:1, S. 39-48.

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	Craig Dilworth: The Metaphysics of Science: An Account of Modern Science in Terms of Principles, Laws and Theories. Springer 2007. Taschenbuch, 336 Seiten. Boston Studies in the Philosophy of Science
	Colin Howson: Hume's Problem: Induction and the Justification of Belief. Oxford: Oxford UP, 2003. Taschenbuch, 272 Seiten Rezension
	David Hume, Peter Millican, Hg.: An Enquiry Concerning Human Understanding. Oxford: Oxford UP, 2008. Taschenbuch, 304 Seiten
	David Hume, David F. Norton, Mary J. Norton, Hg.: A Treatise of Human Nature. Oxford: Oxford UP, 2000. Taschenbuch, 626 Seiten
	David Hume, P. H. Nidditch, L. A. Selby-Bigge, Hg.: Enquiries Concerning Human Understanding and Concerning the Principles of Morals. Oxford: Oxford UP, 1975. Taschenbuch, 458 Seiten
	David Hume: Eine Untersuchung über den menschlichen Verstand. Ditzingen: Reclam, 1986. Taschenbuch, 216 Seiten
	David Hume, Gerhard Streminger, Hg.: Eine Untersuchung über die Prinzipien der Moral. Ditzingen: Reclam, 2002. Taschenbuch, 303 Seiten
	W. H. Newton-Smith, Hg.: A Companion to the Philosophy of Science. Blackwell, 2001.Taschenbuch: 592 Seiten
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© by Herbert Huber, Am Fröschlanger 15, 83512 Wasserburg, Germany, 4.11.2010