 Finally, the proponent of the PSR faces intriguing problems in addressing perfectly symmetrical states. We have seen that some variants of the PSR require an explanation for the existence of things (thus, assuming nonexistence as a “default” state requiring no explanation), while other variants require an explanation for both the existence and nonexistence of things. Let us look quickly at the latter (“default”-free) variant. Specifically, we might wonder how a proponent of the “default”-free variant of the PSR would respond to a situation in which we have neither a reason for the existence of x, nor have a reason for the non-existence of x? A proponent of the PSR might indeed respond by denying the possibility of such a scenario (given the PSR and bivalence). A similar dilemma might be raised with regard to issues of identity: given the absence of a reason for the identity of x and y, as well as for their non-identity, should we assume either identity or non-identity as a default  position?[1]