My advisor was telling me recently about a fight he got into at a conference with another professor (I forget who). This other guy was arguing fervently for the idea that most, if not all, of evolutionary change can be explained by genetic drift. Granted, a lot depended on some…interesting…definitions of terms, but the argument’s out there.
Actually, given that allopatric speciation is thought to be the principle mode of the origin of species, there might not be that far-fetched. Since founder populations may be very small, founder effects and genetic drift are likely to be important in the original populations. But over the long term, and especially if the allopatric population comes back into contact with the source population, selection is likely to produce the greater effects.
Name a few, then, beyond the three I already named. (OK, Herbert Spencer might be one more.) Cite some real historical facts if you are going to make claims like this.
Yes, before Darwin there were evolution-like ideas floating around, but they had more to do with progressivist fantasies of an ever improving world than with science, and the people who held themselves to strict standards of scientific objectivity (including Darwin himself, as a young man) did not take them seriously; rightly so. Charles knew about his grandfather Erasmus’ progressivist evolutionary ideas, but he rejected them as unscientific speculation. He also knew about Lamark’s theories, but regarded Lamark as an incompetent biologist.
However, because of what he saw during the Beagle voyage, and particularly after he came to understand what was going on with the Galapagos finches, Darwin came to realize that the geographical distribution of species around the world, and particularly in relatively isolated environments like oceanic islands (of which he had visited many, not just the Galapagos), made no sense in terms of the hypothesis of a divine designer (no remotely rational God would design that distribution), but made perfect sense in terms of a divergent, branching evolutionary tree, with some branches leading to extinction. This was the first time anyone had come to this realization - because of his voyage, the influence of Lyell’s geological theories on him (note that Lyell also rejected evolutionary ideas as unscientific), and certain aspects of his earlier education, he was uniquely well placed to come to it* - and it the first time that there was any scientific, as opposed to ideological, reason to believe that evolution had happened, and it also involved a considerable firming up of what the pattern of evolution must be like that was not apparent in the earlier ideological evolutionists (except Lamark, who got it wrong).
Once Darwin had become convinced, in this way, that evolution was real, he set to work very deliberately to discover a scientifically viable mechanism for it, a quest which, a I mentioned, took him a few more years. No-one else as looking for such a mechanism at the time, or, indeed, during the 20 subsequent years that Darwin kept quiet about his discoveries, because no-one else, back then, who cared about being scientific, had any good scientific reasons for believing that evolution had actually happened.
*It is no co-incidence that when Wallace came to the same realization, it was after spending a lot of time exploring the biodiversity of islands, in his case the islands of and around what is now Indonesia. In a way, realizing that the geographical distribution of species on islands implies a divergent evolutionary account of species relationships seems to have been the really hard part, the real revolution in biological thinking, and, indeed, once he got there, Wallace seems to have got from there to the idea of natural selection even quicker than Darwin did.