 Thus, Hempel observed, (e1) and (e2) are logically compatible and could all be part of the evidence available when Jones’ prognosis is being considered. The solution Hempel endorsed was the requirement of total evidence, according to which, in reasoning about the world, arguments must be based upon all the available evidence, though he noted that evidence can be omitted when it is irrelevant and its omission does not affect the level of support. Here, when (e1) is combined with (e2), \((\neg\)h1) is better supported than (h1).