  According to this interpretation of the PSR, it is the principle that explains why some contingent truths actually obtain while others do not (there is no sufficient reason for these others to obtain). The PSR is also the reason that led God to actualize this world from among the various possibilities (IP §9); that is, to reiterate the interpretation offered here, it is the principle that explains why our contingent universe exists rather than any number of other such possible, but not necessary, universes. The PSR serves as (a) the principle of becoming (b) of contingent beings only.