 Although these causal theories have subsequently spawned a significant critical literature, other related causal theories have also been advanced. Two of these are teleosemantic theories that are sometimes contrasted with causal theories. (Cf., e.g., Papineau (1984), Millikan (1989), and the entry on    teleological theories of mental content.)  Other more purely causal theories are Dan Lloyd’s (1987, 1989) Dialectical Theory of Representation, Robert Rupert’s (1999) Best Test Theory (see section 3.5 below), Marius Usher’s (2001) Statistical Referential Theory, and Dan Ryder’s (2004) SINBAD neurosemantics.