 Cook Wilson published very little in philosophy: his inaugural lecture, On an Evolutionist Theory of the Axioms (ETA, see also SI, 616–634), a critique of Spencer opening with a very short encomium to Green and Lotze (ETA, 3–4), and a short piece in Mind (CLP) on the ‘Barber Shop Paradox’. In the former, he argued that Spencer’s claim that the criterion of truth p is the impossibility to think its contradictory and that this criterion is the product of evolution is based on a circular reasoning: to prove that the criterion results from evolution, one must apply it. The ‘Barber Shop Paradox’—not to be confused with the ‘Barber’s Paradox’—is attributed to Lewis Carroll (Carroll 1894), but it originated in a private debate about ‘hypotheticals’ with Cook Wilson, who attempted his own solution in CLP (Moktefi 2007a, chap. v, sect. 2), (Moktefi 2007b), (Moktefi 2008, sect. 5.2), while Russell had already satisfactorily resolved it in a footnote to The Principles of Mathematics (Russell 1903, 18). Cook Wilson was also involved on the same occasion in the genesis of Carroll’s better-known ‘paradox of inference’, in ‘What the Tortoise Said to Achilles’ (Carroll 1895), which will be discussed in section 8.