With respect to some individual in a possible world , an individual (not necessarily unique) at a distinct world that most closely resembles with respect to its properties. Developed in philosopher David Lewis’ (1941–2001) work on possible worlds, the theory of counterparts is opposed to the notion of transworld identity, i.e., the thesis that some objects exist at more than one possible world, as an individual at and its counterpart at another world are distinct individuals; it may even be the case that an individual has multiple counterparts at a single world.