In “On the Origin of Species by Means of Natural Selection, or the Preservation of Favored Races in the Struggle for Life”, Darwin did not try to explain the origin of the first life. Instead, he sought to explain the origin of new forms of live from simpler preexisting forms, forms that already possessed the ability to reproduce. His theory assumed rather than explained the origin of the first living thing. His masterpiece contains neither a single mathematical equation nor any report of original experimental research. He developed his theory by drawing together desperate lines of observational evidence and presenting an argument from a novel interpretation of that evidence.
Darwin read “Principles of Geology” by Charles Lyell, whose central methodological principle was. ‘To explain the former changes of the earth’s surface, by reference to causes now in operation.’ According to Lyell, our present experience of cause and effect should guide our reasoning about the causes of past events. Lyell argued that when historical scientist are seeking to explain events in the past, they should not invoke unknown or exotic causes, the effects of which we do not know, instead, they should cite causes that are known from our uniform experience to have the power to produce the effect in question.
Darwin appealed to this principle to argue that presently observed micro evolutionary processes of change could be used to explain the origin of new forms of life in the past [macro evolution]. Since the observed process of natural selection can produce a small amount of change in a short time, Darwin argued that it was capable of producing a large amount of change over a long period of time. In that sense, natural selection was ‘casually adequate’.
Yes Finkelstein I accept micro evolution, I profess by belief that the finches beaks did change but strongly disbelieve that a whale evolved from a mammal. [macro-evolution].