For a more detailed treatment, see Falsifiability.
Falsifiability is a commonly used criterion to determine whether a particular proposition is scientific or non-scientific. Essentially, a proposition is considered "scientific" if it could be proven wrong by experiment, but no experiment has proven it false.
For instance, the proposition "Gravity pulls objects to 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. Because we test it and it is not proven false, we can consider the proposition to be "scientific."
However, other propositions are not testable. For instance, "There is an invisible unicorn in my room." Since there is no way to test whether this proposition is true or not (it's invisible), then it is not scientific to claim that the unicorn is there.
It is important to realize that just because a proposition is unfalsifiable does not mean it is false. There could be an invisible unicorn in my room. But there could also not be. Therefore, there is no scientific basis for making the proposition.
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 a scientific claim.
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, and seeing if it alters 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 such as "humans and apes spring from a common ancestor," 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 water six weeks ago." If there are no witnesses, Creationists argue, then there is no way to test the claim. According to the criterion of falsifiability, therefore, the assertion is not scientific.
Proposed tests of evolution
Several tests have been proposed to test evolution.
In 1949, 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. Creationists typically respond by pointing out that wheels and magnets have been found in nature.
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. Evolutionists typically respond along the lines of proposing a potential line of development (without evidence that the line of development actually occurred, because the alleged development occurred long before scientific observation). Therefore, some have concluded that this is not a meaningful falsification of the theory, because hypothetical lines of development can be proposed to answer the challenge, and those hypothetical lines of development are not themselves testable.
This could be broadened to discovering anything in the fossil record that was grossly "out of place", and indeed others have proposed that finding a human fossil in Jurassic sediments would disprove evolution.
According to creationists:
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 editorswill 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.
Evolutionists acknowledging 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 have the support of Popper himself, as well as other evolutionists.
Although supporting evolution, Popper himself said:
Darwinism is not a testable scientific theory, but a metaphysical research programme.
Popper, trying to distance himself from creationists, later tried to retract the claim. However, he is not the only one to have made similar claims.Birch and Ehrlich previously wrote in Nature:
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.
Dr. Whitten later said:
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.
- 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
- Dewar, Davies and Haldane 1949, p. 90, quoted in Sarfati 2001
- Ridley, M (2003). Evolution, Third Edition. Blackwell Publishing Limited.
- 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.
- Popper 1976, p. 168
- Birch and Ehrlich 1967, p. 349
- 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