 As we have seen, the immediate goal of the argument for substance is to establish that there are things that exist necessarily. In the context of the assumption that anything complex could fail to exist through decomposition, this conclusion entails that there are simples (2.021). While the argument is presented as a two-stage modus tollens, it is conveniently reconstructed as a reductio ad absurdum (The following interpretation of the argument is a compressed version of that provided in Proops 2004. For two recent alternatives, see Zalabardo 2015, 243–254 and Morris 2008, ch.1, and 2017; and for criticisms of Morris, see Potter 2009): 