 Though I think that in general we want to keep value notions out of our philosophical and scientific enquiries—and some would say out of everything else—we might consider what would happen if we relaxed this prohibition to some extent. If we did, there is a whole range of different kinds of value predicates or expressions which might be admitted in different types of case. To avoid having to choose between them, I am just going to use as a predicate the word ‘optimal’ the meaning of which could of course be more precisely characterized later (1982, 237).