Full Idea
Ramsey Sentences are his technique for eliminating theoretical terms in science (and can be applied to mental terms, or to social rights); a term in a sentence is replaced by a variable and an existential quantifier.
Clarification
The 'quantifier' says whether anything exists for the variable to be
Gist of Idea
Mental terms can be replaced in a sentence by a variable and an existential quantifier
Source
Frank P. Ramsey (Law and Causality [1928]), quoted by Thomas Mautner - Penguin Dictionary of Philosophy p.469
Book Reference
Mautner,Thomas: 'Dictionary of Philosophy' [Penguin 1997], p.469
A Reaction
The technique is used by functionalists and results in a sort of eliminativism. The intrinsic nature of mental states is eliminated, because everything worth saying can be expressed in terms of functional/causal role. Sounds wrong to me.