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Line 69: − + − + + − − However, Darwin's own most important contribution to the theory of evolution, his theory of natural selection, is difficult to test. There are some tests, even some experimental tests; and in some cases, such as the famous phenomenon known as 'industrial melanism', we can observe natural selection happening under our very eyes, as it were. Nevertheless, really severe tests of the theory of natural selection are hard to come by, much more so than tests of otherwise comparable theories in physics or chemistry. Line 85:
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Falsifiability of evolution (view source)
Revision as of 21:49, July 16, 2008
, 21:49, July 16, 2008→Evolutionists asserting that evolution is not falsifiable
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Despite this, Popper remained convinced of evolution's legitimacy as a scientific theory:<ref>Popper(1976) 171-172</ref>
Despite this, Popper wrote the following:
{{QuoteBox|And yet, the theory is invaluable. I do not see how, without it, our knowledge could have grown as it has done since Darwin. In trying to explain experiments with bacteria which become adapted to, say, penicillin, it is quite clear that we are greatly helped by the theory of natural selection. Although it is metaphysical, it sheds much light upon very concrete and very practical researches. It allows us to study adaptation to a new environment (such as a penicillin-infested environment) in a rational way: it suggests the existence of a mechanism of adaptation, and it allows us even to study in detail the mechanism at work. And it is the only theory so far which does all that.}}
{{QuoteBox|And yet, the theory is invaluable. I do not see how, without it, our knowledge could have grown as it has done since Darwin. In trying to explain experiments with bacteria which become adapted to, say, penicillin, it is quite clear that we are greatly helped by the theory of natural selection. Although it is metaphysical, it sheds much light upon very concrete and very practical researches. It allows us to study adaptation to a new environment (such as a penicillin-infested environment) in a rational way: it suggests the existence of a mechanism of adaptation, and it allows us even to study in detail the mechanism at work. And it is the only theory so far which does all that.<ref>Popper(1976) 171-172</ref>}}
Popper later reevaluated this view. In "Natural Selection and the Emergence of Mind", Popper wrote the following retraction:<ref>"Natural Selection and the Emergence of Mind", Dialectica, vol. 32, no. 3-4, 1978, pp. 339-355</ref>
Popper later reevaluated this view. In "Natural Selection and the Emergence of Mind", Popper wrote the following retraction:<ref>"Natural Selection and the Emergence of Mind", Dialectica, vol. 32, no. 3-4, 1978, pp. 339-355</ref>
{{QuoteBox|When speaking here of Darwinism, I shall speak always of today's theory - that is Darwin's own theory of natural selection supported by the Mendelian theory of heredity, by the theory of the mutation and recombination of genes in a gene pool, and by the decoded genetic code. This is an immensely impressive and powerful theory. The claim that it completely explains evolution is of course a bold claim, and very far from being established. All scientific theories are conjectures, even those that have successfully passed many severe and varied tests. The Mendelian underpinning of modern Darwinism has been well tested, and so has the theory of evolution which says that all terrestrial life has evolved from a few primitive unicellular organisms, possibly even from one single organism.
{{QuoteBox|When speaking here of Darwinism, I shall speak always of today's theory - that is Darwin's own theory of natural selection supported by the Mendelian theory of heredity, by the theory of the mutation and recombination of genes in a gene pool, and by the decoded genetic code. This is an immensely impressive and powerful theory. The claim that it completely explains evolution is of course a bold claim, and very far from being established. All scientific theories are conjectures, even those that have successfully passed many severe and varied tests. The Mendelian underpinning of modern Darwinism has been well tested, and so has the theory of evolution which says that all terrestrial life has evolved from a few primitive unicellular organisms, possibly even from one single organism.
The fact that the theory of natural selection is difficult to test has led some people, anti-Darwinists and even some great Darwinists, to claim that it is a tautology. A tautology like 'All tables are tables' is not, of course, testable; nor has it any explanatory power. It is therefore most surprising to hear that some of the greatest contemporary Darwinists themselves formulate the theory in such a way that it amounts to the tautology that those organisms that leave most offspring leave most offspring. C. H. Waddington says somewhere (and he defends this view in other places) that 'Natural selection . . . turns out ... to be a tautology' ..4 However, he attributes at the same place to the theory an 'enormous power. ... of explanation'. Since the explanatory power of a tautology is obviously zero, something must be wrong here.
The fact that the theory of natural selection is difficult to test has led some people, anti-Darwinists and even some great Darwinists, to claim that it is a tautology. A tautology like 'All tables are tables' is not, of course, testable; nor has it any explanatory power. It is therefore most surprising to hear that some of the greatest contemporary Darwinists themselves formulate the theory in such a way that it amounts to the tautology that those organisms that leave most offspring leave most offspring. C. H. Waddington says somewhere (and he defends this view in other places) that 'Natural selection . . . turns out ... to be a tautology' ..4 However, he attributes at the same place to the theory an 'enormous power. ... of explanation'. Since the explanatory power of a tautology is obviously zero, something must be wrong here.
I still believe that natural selection works in this way as a research programme. Nevertheless, I have changed my mind about the testability and the logical status of the theory of natural selection; and I am glad to have an opportunity to make a recantation. My recantation may, I hope, contribute a little to the understanding of the status of natural selection.}}
I still believe that natural selection works in this way as a research programme. Nevertheless, I have changed my mind about the testability and the logical status of the theory of natural selection; and I am glad to have an opportunity to make a recantation. My recantation may, I hope, contribute a little to the understanding of the status of natural selection.}}
It is clear, however, that Popper had not really retracted his original 1974 claim regarding Darwinism not being a testable scientific theory, but a metaphysical research programme. In fact in the 1982 revised edition of the book, his original conclusion that "Darwinism is not a testable scientific theory, but a metaphysical research programme" remained.
While Popper maintained that "In its most daring and sweeping form, the theory of natural selection" was "not only refutable but actually refuted"<ref>Popper, 1978, pp.344-345</ref>, this criticism applied only to a subset of the natural selection model of evolution, and not evolutionary science as a whole.
While Popper maintained that "In its most daring and sweeping form, the theory of natural selection" was "not only refutable but actually refuted"<ref>Popper, 1978, pp.344-345</ref>, this criticism applied only to a subset of the natural selection model of evolution, and not evolutionary science as a whole.