In this chapter the distinction between the conceptualist and realist interpretations of predicates is defined and the question of which should be treated in which way is investigated. There are Fs in a purely conceptualist sense if the world is so organized that the concept ‘F’ can be usefully applied to the central cases for which it is devised, but there are no Fs in the realist sense. The realist sense is that, irrespective of what concepts there may or may not be, Fs exist. In the light of this distinction, the application of Kim’s exclusion principle to the non-basic sciences is defended and the inadequacies of modern forms of hylomorphism discussed. Certain currently fashionable philosophical problems can also be solved using this apparatus.