Recent posts by Sal remind me that there are some intelligent educated people who doubt Common Descent. What I don’t understand what they think the alternative is. Put simply I take Common Descent as the position that :
* At one time there was only very simple unicellular life on earth (this is not a debate about how that unicellular life originated)
* Complex life forms (eukaryotes) are created by slight modifications from other life forms (which are their parents). We have never observed them being created any other way!
* All complex life forms are the descended from a very small number of simple life forms – quite possibly just one.
The alternatives I can imagine are:
* Complex life descended many different times from simple life forms – so e.g. mammals descended from a different simple life form from fish. This flies in the face of the fossil record and the hierarchical nature of complex life but I can sort of understand it.
* Complex life from time to time gives birth to wholly different species – massively implausible.
* Complex life is created anew by some process never imagined or observed – even more implausible but presumably what Young Earth creationists believe.
But maybe there is another option?
If Sal or someone could explain I would be interested.