 Lewis’s first, and most important, use of Ramsification was to argue for the mind-brain identity theory, in “An Argument for the Identity Theory”. Lewis claims in this paper that his argument does not rely on parsimony considerations. The orthodox argument for the identity theory at the time, as in e.g. J. J. C. Smart (1959), turned on parsimony. The identity theory and dualism explain the same data, but the dualist explanation involves more ontology than the identity theory explanation. So the identity theory is preferable. Lewis says that this abductive step is unnecessary. (He even evinces concern that it is unsound.) Lewis offers instead an argument from the causal efficacy of experience. The argument is something like the following. (I’ve given the argument that pains are physical, a similar argument can be given for any other kind of experience.)