 So it seems that things are often composed of other things. But under what conditions does composition occur? van Inwagen (1990) calls this ‘The Special Composition Question’ (hereafter ‘the SCQ’). More precisely, the SCQ calls for filling in for Φ in the following sentence: For any xs, there exists a y such that the xs compose y iff Φ. An answer must be non-analytic and must have only ‘the xs’  free.[18]