Falsifiability of evolution

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The falsifiability of evolution is an issue of contention between some creationists and some evolutionists.

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Falsifiability

For a more detailed treatment, see Falsifiability.

Falsifiability is a frequently used criterion in determining whether a particular hypothesis is scientific or conjecture. A hypothesis is considered falsifiable if it is logically possible that it could be proven wrong by experiment or observation. This does not mean that the test or observation must be feasible or logistically possible with our current technology, simply that a logically consistent test or observation must be conceivable.

It is important to realize that just because a proposition is unfalsifiable does not mean it is false. Conversely, just because a proposition is false does not mean it is falsifiable.

This concept falls under the category of Philosophy of Science and is a useful tool in determining the scientific validity of a hypothesis, although not a complete test in and of itself.

For instance, the proposition "Gravity accelerates objects towards the Earth at 32 ft/s2" can be tested by dropping an object in Earth's gravitational field. If we did this and it didn't fall, or it fell at a different speed, we would know that the proposition is false.

However, other propositions are not testable. For instance, "There is an invisible pink unicorn in my room." While the proposition that the unicorn is in the room is testable (by methods other than sight) because said unicorn is invisible, it is impossible to detect colour, and the hypothesis that said unicorn is pink can not rise above conjecture.

In the same way, if a person claims that six weeks ago they drank three glasses of water for the day, there is no way that particular claim can possibly be shown to be false (barring the existence of witnesses). It is therefore not even possible to prove his claim to be wrong, so the claim is said to be unfalsifiable, and therefore not scientifically valid.

A scientific theory seeks to explain a process and thereby make predictions. The falsifiability of a theory is established if it is possible to test these predictions.

Evolution and falsifiability

The first step in determining whether or not "evolution" is falsifiable is defining what, exactly, we mean by "evolution."

  • If "evolution" means the proposition that life changes through generations, and this change is influenced by variation and natural selection, then one could test this proposition by taking a life form, exposing it to the pressures of natural selection, observing the effects over time. Creationists do not dispute the falsifiability, and truth, of this proposition.
  • However, if "evolution" means the proposition that all life descended from a single, primordial protocell by variation and natural selection alone, or other similar claims then creationists dispute the falsifiability of the proposition, asking, "What test can be conducted to show this did not occur?" The problem is similar to the problem of "I drank three glasses of water six weeks ago." If there are no witnesses, Creationists argue, then there is no way to test the claim and that the assertion is therefore not falsifiable.

Evolutionary biologists counter that while direct observation of past events is currently impossible, the theory of common descent could be falsified by tests or observations of the predictions inferred from this theory.

Proposed Tests and Observations

Several tests have been proposed to test evolution.

In 1949[1], J.B.S. Haldane proposed that evolution could be falsified if "various mechanisms, such as the wheel and magnet, which would be useless till fairly perfect" were found in nature. This is substantially the same as the argument for intelligent design below. Creationists typically attempt to falsify evolution on these grounds by pointing out that wheels and magnets have been found in nature, although none have been found in biological organisms to date without a logically possible path of evolution.

Another proposed test has been dubbed instances of "irreducible complexity." Essentially, since evolution requires a step-wise development in which each variation is advantageous enough to survival to spread throughout the gene pool, then evolution with respect to a particular biological structure could be falsified if the components of that organ were found to be totally useless unless already put together. Creationists and Intelligent Design advocates have proposed a number of such structures, including the eye, the cilia of cells, the enzymes involved in human blood clotting, etc. Proponents of evolution have responded by describing hypothetical paths for the evolution of each disputed structure that account for useful function at each stage of development. While it remains unproven that these paths are the actual method by which these structures evolved, they serve to disprove the proposition that it is logically impossible for them to have evolved.

Another test proposed by Haldane was that the discovery of rabbits in Precambrian strata would disprove evolution.[2]

This could be broadened to discovering anything in the fossil record that was grossly "out of place" and unable to be accounted for by other mechanisms, and indeed others have proposed that finding a human fossil in Jurassic sediments would disprove evolution.

Creationists have claimed that evidence supporting this falsification has been suppressed:

Many fossils and artefacts have been found ‘out of place’.7 That is, they are in strata that the evolutionist says represent a period of time when, for example, that organism did not live, or human artefacts could not have been made. There are plenty of examples; some published in respectable journals before the evolutionary paradigm became locked in. Such examples do not get published in modern standard evolutionary journals, possibly because it is inconceivable that such could exist in the evolutionary world-view. In another context, Nobel Prize winner Sir Fred Hoyle said,
‘Science today is locked into paradigms. Every avenue is blocked by beliefs that are wrong, and if you try to get anything published by a journal today, you will run up against a paradigm, and the editors will turn it down.’8

Forbidden Archeology, by Cremo and Thompson, lists some out-of-place human artefacts.9. ...

Human fossils have been found, hundreds of them, but generally in deposits which most creationists would think were post-Flood ... .

In regard to whether things found together necessarily lived and died together, paleontologists can inspect fossils for damage due to ‘reworking’ for clues that the organisms did not necessarily live or die together. However, the ‘reworked’ or ‘stratigraphic leak’ (where something ‘young’ is found in ‘old’ rock) explanation is almost invariably invoked for ‘out-of-place’ fossils.[3]

Other proposed falsifications include:[4]

  • The discovery of a mechanism that would prevent the mutations necessary for evolution from occurring or accumulating.
  • The discovery of true chimeras, such as griffins, centaurs or mermaids that combine parts of diverse forms of life unable be explained by lateral gene transfer or symbiosis. This is not to be confused with different organisms evolving similar characteristics seperately (a process known as convergent evolution) but instead the transfer of entire structures across lines of phylogeny.
  • Direct observation of organisms being created. The observation of a new organism being created that did not inherit characteristics from its progenitors would disprove evolution wholesale.
  • Phylogenetically close organisms that are less genetically similar than they are to phylogenetically distant organisms.[5] The theory of evolution predicts that closely related forms of life should share more DNA than distantly related forms of life. Thus, if humans and chimpanzees shared less of their genome than humans and mice, evolution would be disproven. Tests show that humans and mice have roughly 60 times more differences in their genome than humans and chimps, with whom humans share nearly 99% of their DNA.[6]

Evolutionists asserting that evolution is not falsifiable

Creationists have argued that evolution is not a scientific theory because it is not falsifiable, and in this respect they claim to have the support of Popper himself, as well as other evolutionists. The Swedish cytogeneticist, Antonio Lima-De-Faria, who has been knighted by the king of Sweden for his scientific achievements, noted that "there has never been a theory of evolution".[7][8]

Karl Popper, leading philosopher of science and originator of the idea of falsifiability as a criterion of demarcation of science from nonscience, said:[9][10]

Darwinism is not a testable scientific theory, but a metaphysical research programme...

Despite this, Popper wrote the following:

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.[11]

Later in "Natural Selection and the Emergence of Mind", Popper wrote the following retraction:[12]

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. 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. 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. Yet similar passages can be found in the works of such great Darwinists as Ronald Fisher, J. B. S. Haldane, and George Gaylord Simpson; and others. I mention this problem because I too belong among the culprits. Influenced by what these authorities say, I have in the past described the theory as 'almost tautological', and I have tried to explain how the theory of natural selection could be untestable (as is a tautology) and yet of great scientific interest. My solution was that the doctrine of natural selection is a most successful metaphysical research programme. It raises detailed problems in many fields, and it tells us what we would expect of an acceptable solution of these problems. 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.

While Popper maintained that "In its most daring and sweeping form, the theory of natural selection" was "not only refutable but actually refuted"[13], this criticism applied only to a subset of the natural selection model of evolution, and not evolutionary science as a whole.

He later wrote in a letter to the New Scientist in 1980:[14]

"... some people think that I have denied scientific character to the historical sciences, such as paleontology, or the history of the evolution of life on Earth; or to say, the history of literature, or of technology, or of science. This is a mistake, and I here wish to affirm that these and other historical sciences have in my opinion scientific character; their hypotheses can in many cases be tested."

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.[15] 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.[16] Leading Darwinist and philosopher of science, Michael Ruse acknowledged regarding Popper's statement and the actions he took after making that statement: "Since making this claim, Popper himself has modified his position somewhat; but, disclaimers aside, I suspect that even now he does not really believe that Darwinism in its modern form is genuinely falsifiable."[17]

In NatureBirch and Ehrlich wrote in 1967:[18]
Our theory of evolution has become, as Popper described, one which cannot be refuted by any possible observations. Every conceivable observation can be fitted into it. It is thus outside of empirical science but not necessarily false. No one can think of ways in which to test it. Ideas, either without basis or based on a few laboratory experiments carried out in extremely simplified systems, have become part of an evolutionary dogma accepted by most of us as part of our training. The cure seems to us not to be a discarding of the modern synthesis of evolutionary theory, but more skepticism about many of its tenets" (Ehrlich and Birch, p. 352).
Ehrlich and Birch presented many objections to distinct hypotheses explaining certain aspects of contemporary evolutionary science, but not to the overarching theory itself. A precis set in bold type at the beginning of the article states:
While accepting evolutionary theory, should ecologists be more skeptical about hypotheses derived solely from untestable assumptions about the past? The authors put forward the view that many ecologists underestimate the efficacy of natural selection and fail to distinguish between phylogenetic and ecological questions.

Max Whitten of the University of Melbourne said:[19]

Biologists are simply naïve when they talk about experiments designed to test the theory of evolution. It is not testable. They may happen to stumble across facts which would seem to conflict with its predictions. These facts will invariably be ignored and their discoverers will undoubtedly be deprived of continuing research grants.

Whitten, however was referring not to a fundamental problem with the theory of evolution itself, but with the difficulty of overcoming entrenched ideas in all forms of science. Whitten recently expounded on this in his article "Facts Are Not Everything in Science" for Issues magazine:[20]

Despite what some scientists might think, very little biological research is designed to challenge the robustness of a prevailing worldview like evolution. Some biologists would claim that they are validating the theory of evolution on a daily basis. Not true. If something happens that is consistent with the theory, all well and good. If it doesn’t happen, we will likely find a satisfying explanation within our prevailing worldview. I cannot call to mind a credible experiment that would challenge the theory of evolution.

It is not a technical issue that Whitten addressed, but a social issue throughout research in general.

See also

Further reading

Bibliography

  • Batten, et. al., Don (2007), "January 2007", The Creation Answers Book, chapter 15
  • Birch, L.C. & P.R. Ehrlich (22 April 1967), "Evolutionary History and Population Biology,", Nature 214
  • Dewar, D.; L.M. Davies & J.B.S. Haldane (1949), Is Evolution a Myth? A Debate between D. Dewar and L.M. Davies vs. J.B.S. Haldane, London: Paternoster
  • Popper, Karl (1959), The Logic of Scientific Discovery

Notes

  1. Dewar, Davies and Haldane 1949, p. 90, quoted in Sarfati 2001
  2. Ridley, M (2003). Evolution, Third Edition. Blackwell Publishing Limited.
  3. Batten et. al., 2007, p. 192,193. That quote's footnote's are:
    7. For example: Howe, G.F., Williams, E.L., Matzko, G.T. and Lammerts, W.E., 1988. Creation Research Society studies on Precambrian pollen, Part III: A pollen analysis of Hakatai Shale and other Grand Canyon rocks, Creation Research Society Quarterly 24(4):173–182.
    8. Horgan, J., 1995. Profile: Fred Hoyle. Scientific American 272(3):24–25.
    9. Cremo, M.A. and Thompson, R.L., 1993, Forbidden Archeology. Bhaktivedanta Institute, San Diego, CA, pp. 797–814.
  4. TalkOrigins Claim CA211
  5. 29+ Evidences for Macroevolution Prediction 1.3
  6. New Genome Comparison Finds Chimps, Humans Very Similar at the DNA Level
  7. Altenberg 16: An Exposé Of The Evolution Industry, July 6, 2008, by Suzan Mazur
  8. http://post-darwinist.blogspot.com/2009/05/more-tales-from-altenberg-suzan-mazurs.html
  9. Popper 1976, p. 168
  10. http://members.iinet.net.au/~sejones/PoE/pe05scnc.html
  11. Popper(1976) 171-172
  12. "Natural Selection and the Emergence of Mind", Dialectica, vol. 32, no. 3-4, 1978, pp. 339-355
  13. Popper, 1978, pp.344-345
  14. Letter to New Scientist 87:611, 21 August 1980
  15. http://members.iinet.net.au/~sejones/PoE/pe05scnc.html
  16. http://members.iinet.net.au/~sejones/PoE/pe05scnc.html
  17. http://members.iinet.net.au/~sejones/PoE/pe05scnc.html
  18. Birch and Ehrlich 1967, p. 349
  19. Dr Whitten, Professor of Genetics at the University of Melbourne, who was giving the Assembly Week address in 1980. Quoted by Wieland, Carl, Clash over origins
  20. Facts Are Not Everything in Science: Max Whitten, Issues magazine, May 2008
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