Peter Bowler describes the "non-Darwinian revolution" of the fin-de-siecle, which accepted the basic idea of transmutation of species but substituted for the mechanism of natural selection a whole host of alternatives: orthogenesis, neo-Lamarckism, saltationism
How could an irreducibly complex biological structure come about through evolutionary methods that require gradualism--that go against what is known in biology as saltationism
or the view that completely new living things appeared all at once in discontinuous jumps from what existed before?
This insight then leads Dawkins to embrace (however gingerly) the two implied and conjoined heresies that had been anathema to him: (1) a potential role for phenotypic saltationism
based on underlying rules of continuationist style (I particularly applaud his willingness to consider the possible origin of shovelnosed lobsters by a homeotic mutation that would have to be ranked as a "hopeful monster"); and (2) an acknowledgment that higher-level selection may play an important role in macroevolution (through a principle that he calls, quite fairly in my view, "the evolution of evolvability").