Science, Just Science

23 April 2007

Creationists Don’t Understand Parsimony Again

Filed under: Creationism & Intelligent Design,Science,SJS Comment — Kyuuketsuki @ 1:46 pm

*** Originally posted by Chris Hyland of SJS ***

A claim you’ll often hear is that just because two species, genes etc. share a common ancestor it does not prove that they weren’t intelligently designed. While if you ignore all other evidence apart from the similarity this is technically true, there are a few problems with the argument. The DI claims:

My hope is that one day thinking about Darwinian Theory will become clearer in the public square. Recall that Darwin made two claims:

  1. All living beings descend from one or a few original ancestors, and
  2. The mechanism driving the changes among species is the blind, unguided mechanism of natural selection.

The controversial claim, of course, is the second one—the idea that a purely material mechanism, without any intelligence involved, is responsible for all of the genetic information necessary for life (DNA) and hence for all of life’s diversity.

Clines and others seem to think that evidence for claim one establishes claim two. This is poor thinking. Sequence similarity may indeed be evidence for a common origin—but it does nothing to show that the common origin stems from a material cause rather than an intelligent cause.

Unfortunately when you are looking at a genetic similarity, you have to take into account the massive amount of research which shows that natural selection has been* a major driving force in evolution. Combine this with the fact that there is no evidence that intelligent forces have been* involved in evolution, and parsimony tells us to accept the option that invokes the least unknown entities, and so we end up with evolution.

Second, the 98.8% DNA sequence similarity between chimps and humans that Clines references do not even establish claim one (common ancestry). And “you don’t have to take my word for it,” as LeVar Burton always used to say on Reading Rainbow.

As Francis Collins, head of the project which mapped the human genome, has written of DNA sequence similarities, “This evidence alone does not, of course, prove a common ancestor” because an intelligent cause can reuse successful design principles. We know this because we are intelligent agents ourselves, and we do this all the time. We take instructions we have written for one thing and use them for another. The similarity is not the result of a blind mechanism but rather the result of our intelligent activity.

Here we see the same thing, we are being asked to accept an option that involves the invocation of an extraordinary entity we have no empirical evidence for, when we have another option. It is certainly true that we cannot disprove an intelligent entity was involved in this case, but science is a process that is constrained by several practical implications, one of which forces us to choose the most parsimonious information.

* We require evidence that a process actually was involved, not simply capable. Creationists claim that intelligent processes are capable of generating life, however this does not show that they actually did in a particular case. What we do have is plenty of evidence that evolutionary mechanisms have actually been involved in the diversification of life, not just the knowledge that they are capable.


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