 Modal–dimensionalism differs from Lewis’s theory in a number of important respects but the most striking is the absence of counterpart theory. Modal–dimensionalism eschews counterparts and proposes that to say that you are the leader of a religious cult at a possible world is to say that you yourself exist at that world and are the leader of a religious cult at that world. Another difference between modal–dimensionalism and Lewis’s theory is that unlike the latter, the former avoids the mereological conception of the existence of a possible object at a possible world. According to modal–dimensionalism, just as a temporally or spatially persisting object is (arguably) not part of the temporal or spatial points or regions at which it exists, a modally persisting object is not part of the possible worlds at which it exists. Modal–dimensionalism also differs from Lewis’s theory in not being a thoroughly reductionist theory. It does not analyze the notion of a possible world in mereological terms but leaves it as largely primitive (Yagisawa 2002, 2010, 2017). This enables modal–dimensionalists to allow the possibility of there being no concrete object, whereas on Lewis’ theory, if there is no concrete object, there is no possible world. For a different attempt to reconcile possibilist realism with the possibility of the non-existence of anything concrete, see Rodriguez-Pereyra 2004.