 To come back to Cook Wilson, he grappled here with related problems. It is implied by the above that knowledge requires a sort of warrant very much akin to a proof and, consequently, “we are forced to allow that we are certain of very much less than we should have said otherwise” (Prichard 1950, 97). Mathematical knowledge appears paradigmatic. As Prichard put it: “In mathematics we have, without real possibility of question, an instance of knowledge; we are certain, we know” (Prichard 1919, 302). (Joseph used this view to argue against Mill’s empiricist account of mathematics, using ‘intuition’ where Cook Wilson would use ‘apprehension’ (Joseph 1916a, 543–553).) Alas, Cook Wilson put forth the axiom of parallels in Euclidean geometry as an example of knowledge, and dismissed non-Euclidean geometries as inconsistent (see section 1). If for any p such as the axiom of parallels, someone fails to ‘apprehend’ it, then all he could do is, somehow lamely, ask them to try and “remove […] whatever confusions or prejudices […] prevent them from apprehending the truth of the disputed proposition” (Furlong 1941, 128).