I ran across an interesting piece today on talkorigins: “Evolution is a Fact and a Theory”. Like so many other words, one word is used to describe two different things:
- The fact that organisms evolve over time.
- The theories of the mechanisms by which organisms evolve.
Sure, I’m a little late to the party, where scientists have made this distinction for a quarter of a century. But it’s new to me, and I thought it was a cool distinction. I’ll use it in the future when discussing this with friends who try to lump it all together as “Darwinism”. One worthwhile quote from the talk.origins site:
It is time for students of the evolutionary process, especially those who have been misquoted and used by the creationists, to state clearly that evolution is a fact, not theory, and that what is at issue within biology are questions of details of the process and the relative importance of different mechanisms of evolution. It is a fact that the earth with liquid water, is more than 3.6 billion years old. It is a fact that cellular life has been around for at least half of that period and that organized multicellular life is at least 800 million years old. It is a fact that major life forms now on earth were not at all represented in the past. There were no birds or mammals 250 million years ago. It is a fact that major life forms of the past are no longer living. There used to be dinosaurs and Pithecanthropus, and there are none now. It is a fact that all living forms come from previous living forms. Therefore, all present forms of life arose from ancestral forms that were different. Birds arose from nonbirds and humans from nonhumans. No person who pretends to any understanding of the natural world can deny these facts any more than she or he can deny that the earth is round, rotates on its axis, and revolves around the sun.
The controversies about evolution lie in the realm of the relative importance of various forces in molding evolution.
– R. C. Lewontin “Evolution/Creation Debate: A Time for Truth” Bioscience 31, 559 (1981) reprinted in Evolution versus Creationism, op cit.
This ties into a concept that I’ve been toying with in my mind for the past couple of weeks. Daniel C. Peterson, noted Mormon apologist, pointed out on a thread at http://www.mormonapologetics.org/ that writers there often fall prey to the Fallacy of the Beard:
Q: Does one grain of wheat form a heap? A: No. Q: If we add one, do two grains of wheat form a heap? A: No. Q: If we add one, do three grains of wheat form a heap? A: No. … Q: If we add one, do one hundred grains of wheat form a heap? A: No. Q: Therefore, no matter how many grains of wheat we add, we will never have a heap. Therefore, heaps don’t exist!
So the same with the fact of evolution, and the theories of the mechanisms of evolution. Some maintain that, because science can never claim any conclusion with absolute certainty, evolution can never be a “fact”. Yet science is nothing more than the study of the natural world; every thing we can perceive with our senses carries with it information about itself, and these are the facts from which we can base our conclusions. Sure, our conclusions are provisional, but in some cases these conclusions are sure enough, and used successfully across enough disciplines, to be considered “fact”.
Just like I can tell that I have a substantial beard today. And I’m about ready to shave it off because it’s bugging me.