Inferring and Explaining

74 InferrIng and exPlaInIng believed that there was a very strong correlation between the diferent stages of the history of life—its phylogenetic structure and the difer- ent stages of an individual’s embryonic devel- opment. Tus one of Darwin’s contemporaries, Ernst Haeckel, claimed ontogeny is a concise and compressed recapitulation of phylogeny, conditioned by the laws of heredity and adaptation. 13 We now know that the recapitulation theory is mistaken and that embryonic development is much more complicated than either Darwin or Haeckel could have ever imagined. Darwin con- ceivedof descentwithmodifcationas applying to individuals exemplifying a species—that species’ phenotype (its appearance and behavior).Modern biology, though, also includes the descent with modifcation of its genotype (the genetic instruc- tions for building the phenotype) and if thatwere not complicated enough, it also must include the descent withmodifcation of the underlying bio- chemical processes that take the information in the genotype and physically develops the individ- ual. We are really only just getting a handle on all this in the twenty-frst century. 14 Darwin’s Evidence for Descent with Modifcation Te evidence can now be schematized. e 1 . The earth is much older than had been previously believed—thousands of millions of years. e 2 . The fossil record e 3 . The natural system e 4 . Patterns of geographical distribution e 5 . Morphological commonalities e 6 . Embryological oddities t 0 . Descent with modifcation Te central question in inference to thebest expla- nation is always the same—is t 0 the best explana- tion?We’ve alreadydiscussed the two serious rival explanations in Darwin’s time. t 1 . Fundamentalist special creation t 2 . Relaxed special creation Within ten years or so of the publication of On the Origin of Species , say 1870, up to this frst decade of the twenty-frst century, there has been clear, overwhelming consensus in the broad scientifc community that descent with modifcation—evolution—does such a mani- festly better job of explaining all this uncontro- versial data and that the evidence is so strong that we can talk of common descent as a scien- tifc fact . You, of course, must rank order the explanations for yourself. Some of you will insist on a diferent ranking, and I maintain that is your moral and intellectual right. My job as a philosopher and a teacher is accomplished if you can simply see why Darwin, his contemporaries, and his scientifc descendants all thought the evidence was so powerful. I do want to remind you, however, that many traditional theists have seen complete consistency betweenmainstream religious doctrine and evolution. Consider the words of Richard Swinburne, formany years the Nolloth Professor of the Philosophy of the Chris- tian Religion at the University of Oxford, at the beginning of his book Te Evolution of the Soul :