I recently found this comment from intelligent design theorist Davescot:
“Every living thing ever observed, where its origin can be determined, descended from another living thing. This has been observed I’m sure billions of times by now by billions of people. Life comes from life. I know of no exception to that rule. In science, when we find phenomenon that are widely observed countless times with never an exception, it’s labeled not a hypothesis or theory, but a law of nature. Life comes from life is a law of nature. It is as well tested as gravity.
“While we cannot turn back time and witness things millions and billions of years ago, it takes some kind of extraordinary evidence to reasonably purport a law of nature operating differently in the past. This applies to the law of gravity, which predicts that things fall down instead of up, and to the law of life, which predicts that every living thing has a parent.”
Couldn’t have said it better myself. Incidentally, there’s some question in mind as to whether Common descent is compatible at all with intelligent design. Common descent only makes predictions about the evidence because we know what effects it is supposed to leave behind (we see reproduction going on all the time). If reproduction, inheritance, and mutation worked in some dramatically different way than they do now (as in: a dinosaur hatched a baby chicken or something equally crazy) then the theory of common ancestry would not be able to explain anything because then anything and everything would be possible. The only kind of common descent theory that makes predictions is the one that says reproduction with variation and inheritance happened back then just like it happens now. If it were otherwise, we’d have no reason to expect transitional fossils or any type of patterns in anatomy, development and genetics (if the laws were broken, a monkey could birth a human baby, the entire genetic code could be scrambled and drastically altered in a single generation, preserving no clues of the past).
Of course, there is still one type of design compatible with common descent, and that is thomism: the thomist philosophy holds that laws of nature and acts of god are not mutually exclusive: they’re the same thing. A thomist holds that God carefully controls everything, determining by his will every single event, and so what we humans call laws of nature are really just “the way God usually does things” and are not just properties of nature. To give an example: most people might say that the amount of matter in the universe is the same from one moment to the next because of the law of conservation. But this is incorrect: “the law of conservation” does nothing more than describe the fact that the amount of matter stays the same, it does not explain why it does. The thomist believes that the explanation of why matter stays the same is that God controls everything, and he wills it to stay the same.
Now the thomist philosophy is a possible way to reconcile God and evolution. However, it still seems pertinent to ask this: why exactly does God act this way? And why the bad mutations, extinctions, billions of years of evolution before humans, and so on? Wouldn’t it just be easier to say that there’s no man behind the curtain?
I’d like to end this with the rest of the quote from DaveScot:
“It was pointed out to me that Dr. Stephen Meyer had questioned whether the universal genetic code, which has been known for some time to be not quite universal, suggests multiple instances of the origination of life. Over a year I looked at this very thing myself. Since there’s no empirical evidence at all contrary to the law of nature that life comes from life, one has to look for indirect evidence of exceptions. The obvious place to start is the universal genetic code. So I went to the code depository
“and checked out the deviations from the standard code. Glaringly obvious is that the differences are very small – one base here, another there. While this begs the difficult question of how these differences arose in a common descent scenario, what it does not do is cast any reasonable doubt on common descent. Why? Because the points of similarity overwhelm the points of difference. If one wants to say there were independent origins due to the small differences one also needs to explain the remaining similarity.
Carl Woese’s theory
“proposes that instead of one universal common ancestor there were three – bacteria, archaea, and eukaryotes – which came to have a high degree of simililarity today through horizontal gene transfer. Three common ancestors billions of years ago isn’t much dissent from descent from one ancestor. Moreover, eukaryotes include every member of the plant and animal kingdoms which, accoreding to Woese, would still have a single common ancestor. For the purposes of this discussion, a single common ancestor for all plants, all animals, all fungi, and all protists is essentially still common descent. None of us are really concerned about bacteria having an ancestor different from fig trees and humans are we? Fig trees and humans still have the same common ancestor in Woese’s theory.
“Russel Doolittle is saying basically the same thing as Woese.
“At the end of the day we still the law of nature that life comes from life, an overwhelming number of points of similarity in the genetic code, and the best scientific objections to a single common ancestor (Woese and Doolittle) still saying that all plants, animals, fungi, and protists share a single common ancestor.”