  Two main difficulties face this approach. First, although philosophers have offered various arguments for the thesis that thought is not explanatorily prior to language, none of the arguments commands widespread assent. Christopher Peacocke (1998) forcefully criticizes many of the most well-known arguments. As things stand, the objection constitutes not so much a problem for conventional theories as a prospectus for a rival research program. The second and more serious difficulty is that, so far, the rival research program has not yielded results nearly as precise or systematic as existing conventional theories. Perhaps the two most commanding theories within the rival research program are Davidson’s (1984) and Brandom’s (1994). Many contemporary philosophers feel that both theories enshrine an overly “anti-realist” conception of mental content. Moreover, neither theory yields detailed necessary and sufficient conditions for linguistic meaning analogous to those provided by Lewis.