I received my copy of Theistic Evolution today. The book contains three chapters dedicated to skepticism of universal common ancestry. As common descent seems to be a hot topic here lately I thought I’d read those chapters first and offer comments and invite responses.
I’ll start with Chapter 12, authored by Paul Nelson, which carries the title: Five Questions Everyone Should Ask about Common Descent. The five questions are as follows:
1. If species were not connected by common descent, how would we know it?
2. What were the actual transformation pathways, satisfying the continuity rule, which connect all organisms to LUCA?
3. Have we genuinely tested UCD, or merely assumed its truth?
4. When explaining the history of life, have we assumed methodological naturalism only, or have we allowed for the possibility of intelligent design?
5. In the light of intelligent design as a causal possibility, what histories for life on earth might be the case?
As usual, I don’t expect anyone else here to actually read this book because, you know, it just isn’t skeptical enough.
Rather than post the content of the abstract for the chapter I post a link here to where it can be found:
Nelson begins by claiming that biologists are abandoning universal common descent. He then goes on to echo a claim made here by Salvador in the Common Design vs. Common Descent thread that the theory of common descent must explain not the similarities, but the differences.
…common descent is not mainly a theory of similarity. … Rather, common descent is mainly a theory of transformation. … Common descent must explain the origin of differences – novel characters – and not simply similarities, along natural pathways or branching lineages starting with an ancestral form which did not possess those characters.
Salvador’s claims didn’t get far here but Nelson’s reasoning is a bit more clear. Is it possible that Salvador had a valid point that was dismissed on grounds that had nothing to do with evidence, facts and reason?
Note: Nelson never appeals to “common design” as a better explanation.