 Sober gives a related but stronger argument based on observational selection effects (Sober 2009, 77–80). Say that Jones nets a large number of fish from a local lake, all of which are over 10 inches long. Let hall= ‘all of the fish in the lake are over 10 inches long’ and h1/2= ‘Half of the fish in the lake are over 10 inches long’. The evidence e is such that P(e | hall) &gt; P(e | h1/2). Now say that Jones discovers that his net is covered with 10 inch holes, preventing him from capturing any smaller fish. In that case, e does not favor one hypothesis over the other. The evidence e is an artifact of the net itself, not a random sample of the fish in the lake. 