 Since the mid-1980s the main rival to TT has been the simulation theory, or ST, of which there are many varieties. The major proponents of ST diverge in their views about what exactly simulation involves. They heterogeneously characterize the process of simulation as a form of imaginative transformation (Gordon 1986, 1995, 1996), thought replication or co-cognition (Heal 1986, 1995, 1996, 1998a, 1998b), introspective modeling (Gopnik &amp; Wellman 1992) and off-line practical reasoning (Goldman 1989, 2006).