 Although Williamson has picked up the Oxonian banner of ‘knowledge first’, this is one point where he did not follow Cook Wilson and Prichard, since he argued against the ‘knowing that one knows’ principle with help of the notion of ‘luminosity’. A condition C is said to be ‘luminous’ if and only if for every case a, if C obtains in a then in a one is in a position to know that C obtains (Williamson 2000, 95). Williamson (2000, chap. 4) provided arguments against ‘luminosity’, thus that one can know without being able to know that one knows. 