Claim CB340:
Organs and organ systems would have been useless until all the parts were
in place. The coordinated innovation that they require is too improbable
for evolution to create in one step.
Source:
Plantinga, Alvin, 1991. When faith and reason clash: Evolution and the
Bible. In: Intelligent Design Creationism and Its Critics,
ed. R. T. Pennock, Cambridge, MA: MIT Press, 2002, pp. 113-145.
Orig. pub. in Christian Scholar's Review 21(1): 8-32.
Response:
- This claim is an instance of the argument from
incredulity. In
all specific instances of this claim, there are ways for the organs and
organ systems to evolve gradually. The idea that they could not evolve
usually involves one or more of the following errors in thinking:
- that organ parts appear suddenly. This seems to be an artifact of
creationist thinking. Evolution, however, is not creationism;
parts change gradually.
- that organs less developed than what exists now must be completely
useless. This is nonsense. A light-sensitive patch on the skin
may not be as useful as the eyes we have now, but it is better than
nothing. And just a little bit better is all that is required for
the trait to evolve.
- that parts must evolve separately. Coordinated innovation between
parts of an organ or organ system is possible. Indeed, if the
parts evolve gradually, it is inconceivable that parts that
interact would not coevolve in such a way that changes are
coordinated via natural selection.
- that parts do not change function. Many organs do not start from
nothing. Rather, they start as a part that serves a different
function and gradually gets co-opted for a new function. For
example, tetrapod legs evolved from fins.
The invalidity of specific examples of this claim are seen in the
the bombardier beetle,
the giraffe neck,
the woodpecker tongue,
and the fangs of venomous snakes.
- Sometimes multiple coordinated changes can occur when there is a
mutation in a regulatory gene.
Further Reading:
Dawkins, Richard, 1995. <#River out of Eden#>. New York: Basic Books.
created 2003-4-9
