 Spinoza accepts a very strong version of the PSR. According to some readings, he grants the PSR unlimited extension, and takes it to be necessary. In fact, the PSR seems to be the primary motivation behind Spinoza’s strict necessitarianism. For Spinoza, if there are two (or more) possible worlds, it would seem that neither one would have a sufficient reason or cause (for if there were such a sufficient reason, this world would be necessitated, and all other worlds would be impossible). In other words, for Spinoza, the PSR dictates that there is only one possible world (see Della Rocca 2008: 69–78, and Lin 2011: 23–25. Occasionally, however, Spinoza’s endorsement of the PSR is in tension with other principles of his metaphysics, such as the priority of the infinite (see Melamed 2012b and Melamed 2013a: xvii).