Methodological Solipsism

Classical cognitive science explains psychological phenomena by appealing to the representational states of agents.  Different behavioral predictions must be grounded in different representational states.  A representational theory of mind must therefore be capable of individuating different representational states.  This could be done in terms of their content (i.e., different states must refer to different entities in the world), but there are well-known philosophical problems with this approach (Pessin, Goldberg, & Putnam, 1996).  An alternative approach that has strongly influenced classical cognitive science is methodological solipsism (Fodor, 1980).  In methodological solipsism, representational states are individuated only in terms of their relations to other representational states.  Relations of the states to the external world – the agent’s environment – are not considered.  “Methodological solipsism in psychology is the view that psychological states should be construed without reference to anything beyond the boundary of the individual who has those states” (Wilson, 2004, p. 77).

References:

1. Fodor, J. A. (1980). Methodological solipsism considered as a research strategy in cognitive psychology. Behavioral and Brain Sciences, 3(1), 63-73.
2. Pessin, A., Goldberg, S., & Putnam, H. (1996). The Twin Earth Chronicles: Twenty Years Of Reflection On Hilary Putnam's "The meaning of 'meaning'". Armonk, N.Y.: M. E. Sharpe.
3. Wilson, R. A. (2004). Boundaries Of The Mind: The Individual In The Fragile Sciences: Cognition. Cambridge, U.K. ; New York: Cambridge University Press.

(Added October 2010)