Dr. Cartwright is mistaken. Darwin asserted that all natural biological complexity arose by random undesigned variation and natural selection.
Anyone familiar with Darwin would understand that this is incorrect. In fact, Darwin is clear that he considers natural selection one of various mechanisms, although he considered it the most relevant one. Also, Egnor may want to familiarize himself with the concept of randomness as used by Darwin. In fact, Darwin used an analogy to artificial selection to formulate his thesis of natural selection, in other words, one may argue that in this sense, Darwin identified the designer.
Charles Darwin wrote:
Furthermore, I am convinced that Natural Selection has been the main but not exclusive means of modification.
Source: Origin of Species, Introduction, page 6