The creationists and ID-ologists claim that it is impossible for complex organisms or traits to evolve by mere chance. Their examples are something like the impossibility of an airplane assembling from a storm in a junkyard or the ostensible irreducibility of complex traits. The Darwin-conspiracy theorists claim the impossibility that the full blown theory of evolution by means of natural selection precipitated independently and from scratch in the minds of Matthew, Wallace and Darwin around the same time. They, too, ignore the predecessors and assume an impossible event that was not necessary for the outcome.
|Their false alternatives have no bite|
Where the former see the whole of nature as a big conspiracy pointing towards a creator, the latter see the convergence of ideas as a conspiracy of Darwinists against Wallace, Matthew, or Blyth alternatively.
If we consider the predecessors, however, it is clear that natural selection was not a yet undiscovered idea. On the contrary, it existed in many different contexts (see here, here, here, here and here). Ironically, before Matthew (1831), natural selection was thought to keep the species fixed. We'd now say, they only considered stabilising selection and failed to see the possibility of directional selection.
|T.R. Malthus (WikimediaCommons)|
Let's see, then, whether anything in Malthus's essay comes so close, that we can comprehend the independent emergence of the idea of evolution through natural selection. (Six times between 1813 and 1858 by Wells 1813/1818, Adams 1814, Matthew 1831, Spencer 1852, Wallace 1858 and Darwin 1858.)
Malthus (1798, p. 11) starts from two simple postulates:
"I think I may fairly make two postulata.From these postulates he deduces a law of nature (Malthus 1798, p. 13f):
First, That food is necessary to the existence of man.
Secondly, That the passion between the sexes is necessary and will remain nearly in its present state."
"Assuming then my postulata as granted, I say, that the power of population is indefinitely greater than the power in the earth to produce subsistence for man.
Population, when unchecked, increases in a geometrical ratio. Subsistence increases only in an arithmetical ratio. A slight acquaintance with numbers will shew the immensity of the first power in comparison of the second.
By that law of our nature which makes food necessary to the life of man, the effects of these two unequal powers must be kept equal.And he illustrates the effect of that law of nature (Malthus 1798, p. 15):
"The race of plants and the race of animals shrink under this great restrictive law. And the race of man cannot, by any efforts of reason, escape from it. Among plants and animals its effects are waste of seed, sickness, and premature death. Among mankind, misery and vice."Malthus's law of nature can justly be called by its current name, which is natural selection. The only thing that is still missing, is the idea of heritable variation acting in concert with this natural selection. That a lot of variation is heritable, however, was a triviality for plant and animal breeders of all stripes. Is it then not comprehensible, how various scholars independently combined these explanatory parts into similar or even identical theories of evolution through natural selection?