Natural selection is a tautology: the fittest survive, and those who survive are the fittest.
I. Not a tautology
The fitness of an organism is never defined in terms of the organism's ability to survive (though it has some relation to its ability to survive to reproductive age). The fitness of an organism is defined in terms of the organism's expected reproductive success.
With this said, philosopher Robert Pennock explains the problem with the creationist claim:
Consider the formula: May the best man win. It seems harmless, but the creationist now points out that we determine which team is best by seeing which wins. If that is what it means to be "best," then the expressed wish seems to reduce to "May the team that wins be the team that wins." It is thus vacuous dogma, objects the creationist, to subsequently explain who won in terms of one team's being "better" than the other. However, we sports fans are not fooled into abandoning the game by such arguments. Of course we do determine which is the best team by looking at its record of wins, and we would certainly explain why it won the trophy by noting its superior record over its rivals. But we understand that this is not the end of the story...even though we do judge on the basis of record, we do not doubt that it is the physical traits of a team, its superior characteristics and playing ability, that make it better than the others. Understanding this, we also understand that it is possible that the best team might not win...This parallels the distinction that biologists make between evolution by natural selection and evolution by natural drift, and the mere fact that we recognize such distinctions is by itself sufficient to show that the tautology objection does not hold in either sports or evolutionary theory. (Pennock 1999:101)
Pennock is pointing out what Mills and Beatty (1979:11) explicitly state: that the fitness of an organism is best described in terms of the organism's propensity to leave offspring, not in terms of its actual reproductive success, which can be affected by pure happenstance. To put it simply, a moose with all of the "right" genes can still get clocked on the head by a meteorite before it gets lucky, while its sickly neighbor goes on to sow its seed far and wide. Since propensities do not automatically translate into actual reproductive success, the idea of fitness, and the natural selection of the fittest, cannot be tautologous.
II. Disavowal by a creationist organization
To its credit, the young-earth creationist organization Creation Ministries International advises against using this argument (CMI n.d.).
CMI. n.d. Arguments we think creationists should NOT use. creation.com/arguments-we-think-creationists-should-not-use. Spotted 21 Nov 2014.
SK Mills and JH Beatty. 1979. The propensity interpretation of fitness. In Sober 1994:3-23.
RT Pennock. 1999. Tower of Babel: The Evidence against the New Creationism. Cambridge, Mass: MIT Press.
E Sober (ed.). 1994. Conceptual Issues in Evolutionary Biology: Second Edition. Cambridge, Mass: MIT Press.
Last updated: 21 Mar 2008
Copyright © 2017, Mark Vuletic. All rights reserved.