 Chalmers (2002a, 2010) and Jackson (1998) have tried to support their modal monism by arguing that it is gratuitous to postulate two forms of modality, given that all the phenomena pointed out by Kripke can be accommodated by appeal to a single kind of modality. Dualists may reply that the greater simplicity in the view of modality has been achieved only by adding complexity to the semantic theory. That response could be answered by arguing that two-dimensional semantics can be motivated by independent considerations. That, of course, is controversial, as is the general viability of two-dimensional semantics (see the entry  two-dimensional semantics  for detailed discussion).