I’m splitting this off as a new topic – partly to experiment with ways of using the board software to do that.
Please keep in mind that I am not a biologist. I hope some actual biologists will chime in and say where they disagree.
Darwin quite possibly did consider his ideas to be an hypothesis about origins. And Darwin made some mistakes, such as an over-emphasis on natural selection. This is understandable, since that was about all that he had at the time.
However, an hypothesis doesn’t get you very far. And, before long, biologists had taken this far beyond the level of an hypothesis. They saw evolution as a framework for studying biological change. In a way, Linnaeus started this with his classification system that particularly emphasized reproduction and reproductive organs as a way of sorting out the species. And once they knew of Mendel’s work on genetic, that was quickly incorporated into the study.
I’m inclined to see evolutionary theory as including reproduction, genetics, development (as in evo-devo), mutation and speciation. And I probably left out some of what should be included.
Frameworks are important to most science.
Philosophy of science tends to describe science as a system of descriptions that uses induction to advance the field. I mostly disagree with this. I see science as producing logical (and mathematical) models of aspects of the world. And the model allows mapping of real world phenomena into logic propositions. A theory often has many technical definitions which are part of the constructing of the model.
I also think Quine (the philosopher) made a mistake when he argued against the analytic/synthetic distinction. In a scientific theory, the technical definitions and part of the core of the theory are analytic propositions, while experimental science produces synthetic propositions (measurements, observations, etc).
What we see seems well explained by common descent. But I’m not sure what you are looking for.
Try comparing a bonsai tree with a natural growing tree. The growth of the bonsai tree was carefully controlled from when it was a seedling. Similarly, small changes that affect the development stage of an organism can result is quite large apparent changes in the resulting adult form.
This is where I see problems. According to Harshman common descent explains the similarities but not new features. I agree with this but then common descent is not an explanation of ancestry only similarities and differences we can attribute to reproduction.
For common descent to explain ancestry between reptiles and mammals it has to explain how the placenta which is a new feature emerged from reproduction. Emergence of a new features is not a claim of common descent according to Harshman.
Common descent only explains the similarities and differences we would expect from reproduction.
At this point Harshman is claiming common ancestry=common descent so there is still stuff to work out. In my opinion the only way to close this gap is if you can explain new features with reproduction (and the variation that comes with it) alone and there is little evidence supporting this claim. Reproduction would have to be able to create lots of novel FI and it does not appear to do that.
What you mean, apparently, is that common descent explains the pattern of similarities and differences among species and nothing else. But that’s all it’s ever been claimed to explain. This is like criticizing Schrödinger’s equations for failing to explain the orbit of Venus. All explanations are limited; they’re limited to explaining relevant phenomena.
It appears that they can. But note that this has nothing to do with evidence for common descent.
We agree here as I am yielding to your definition of common descent.
On what basis do you think that mutation and selection can build an eye? If we would through lots of discussion conclude mutation and selection is a poor explanation for the origin of the eye how do you think evolutionary theory would be impacted?