Essay:Evolution is an unproved theory
Skeptics of some aspects of evolutionary theory sometimes claim that evolution is an unproven theory. It is true that the hypothesis that each species of life in existence now evolved naturally from a common annecestor, like any other scientific hypothesis, cannot be definitively proved. However, that hypothesis and the hypothesis that all life on earth descends from one common ancestor is corroborated by molecular  fossil  geographical  and morphological  evidence. Skeptics sometimes make the argument that evolution is just a theory or an unproved theory. For example, Pope Benedict XVI recently published Creation and Evolution, in which he writes "[It] is also true that the theory of evolution is not a complete, scientifically proven theory."
Some creation scientists have argued that the evolution of all life on Earth from a common annecestor is not a falsifiable hypothesis and as such should be considered a pseudoscience according to criteria proposed by the renowned philosophy of science Karl Popper. The falsifiability principle essentially states that scientific theories are testable, and theories that are not testable are not scientific. Observations that corroborate theories not sufficient to establish status as science under Popper's falsifiability criteria. The concept of falsifiability, coined in Popper's book, The Logic of Scientific Discovery, led Popper to classify evolution as a "metaphysical research programme."
Evolutionary devotees counter, however, that evolution is falsifiable. Most famously, the English biologist JBS Haldane argued that "fossil rabbits in the precambrian" would falsify evolution--while arguing that the theory of evolution is a scientific theory even under Popper's falsifiability criteria.
In 1980, Popper responded to news that his conclusions were being used by creation-scientists by affirming that theories regarding the origins of life on earth were scientific because "their hypotheses can in many cases be tested," but he stopped short of granting full scientific standing to evolution. With Popper's equivocal stance on evolution not resolving the matter, Douglas Theobald argues at TalkOrigins, a pro-evolution website, cataloged 30 major biological predictions of evolution, with "potential falsifications".
- Brown, J. R. and W. F. Doolittle. 1995. Root of the universal tree of life based on ancient aminoacyl-tRNA synthetase gene duplications. Proceedings of the National Academy of Sciences of the United States of America 92:2441-2445.
- Caetano-Anolles, G. 2002. Evolved RNA secondary structure and the rooting of the universal tree of life. Journal of Molecular Evolution 54: 333-345.
- Gribaldo, S. and P. Cammarano. 1998. The root of the universal tree of life inferred from anciently duplicated genes encoding components of the protein-targeting machinery. Journal of Molecular Evolution 47:508-516.
- Carroll, R. L. (1997) Patterns and Processes of Vertebrate Evolution. Cambridge: Cambridge University Press.
- Sereno, P. C. (1999) "The Evolution of Dinosaurs." Science 284: 2137-2147
- MacFadden, B. J. (1992) Fossil Horses: Systematics, Paleobiology, and Evolution of the Family Equidae. New York, Cambridge University Press.
- Darwin, Charles (1859), On the Origin of Species by Means of Natural Selection, or the Preservation of Favoured Races in the Struggle for Life, London: John Murray 1st edition.
- Creation and Evolution, Pope Benedict XVI, 2007, Sankt Ulrich Publishing.
- Popper 1976, p. 167-180 as quoted by Number 1992, p. 247
- Ridley, M (2003). Evolution, Third Edition. Blackwell Publishing Limited.
- Popper 1980, p. 611 as cited in Numbers 1992, p. 247
- Numbers 1992, p. 247
- Theobald, Douglas (2004) 29+ Evidences for Macroevolution: Scientific "Proof", scientific evidence, and the scientific method. The TalkOrigins Archive. Retrieved on 2007-05-12.