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14. Science / B. Scientific Theories / 8. Ramsey Sentences

[procedure to reduce metaphysical commitment in theories]

8 ideas
Mental terms can be replaced in a sentence by a variable and an existential quantifier [Ramsey]
     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.
     From: Frank P. Ramsey (Law and Causality [1928]), quoted by Thomas Mautner - Penguin Dictionary of Philosophy 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.
There is a method for defining new scientific terms just using the terms we already understand [Lewis]
     Full Idea: I contend that there is a general method for defining newly introduced terms in a scientific theory, one which uses only the old terms we understood beforehand.
     From: David Lewis (How to Define Theoretical Terms [1970], Intro)
     A reaction: Lewis is game is to provide bridge laws for a reductive account of nature, without having to introduce something entirely new to achieve it. The idea of bridge laws in scientific theory is less in favour these days.
A Ramsey sentence just asserts that a theory can be realised, without saying by what [Lewis]
     Full Idea: If we specify a theory with all of its terms, and then replace all of those terms with variables, we can then say that some n-tuples of entities can satisfy this formula. This Ramsey sentence then says the theory is realised, without specifying by what.
     From: David Lewis (How to Define Theoretical Terms [1970], II)
     A reaction: [I have compressed Lewis, and cut out the symbolism]
It is better to have one realisation of a theory than many - but it may not always be possible [Lewis]
     Full Idea: A uniquely realised theory is, other things being equal, certainly more satisfactory than a multiply realised theory. We should insist on unique realisation as a standard of correctness unless it is a standard too high to be met.
     From: David Lewis (How to Define Theoretical Terms [1970], III)
     A reaction: The point is that rewriting a theory as Ramsey sentences just says there is at least one realisation, and so it doesn't meet the highest standards for scientific theories. The influence of set-theoretic model theory is obvious in this approach.
The Ramsey sentence of a theory says that it has at least one realisation [Lewis]
     Full Idea: The Ramsey sentence of a theory says that it has at least one realisation.
     From: David Lewis (How to Define Theoretical Terms [1970], V)
If I used Ramsey sentences to eliminate fundamentality from my theory, that would be a real loss [Sider]
     Full Idea: If the entire theory of this book were replaced by its Ramsey sentence, omitting all mention of fundamentality, something would seem to be lost.
     From: Theodore Sider (Writing the Book of the World [2011], 02.2 n2)
     A reaction: It is a moot point whether Ramsey sentences actually eliminate anything from the ontology, but trying to wriggle out of ontological commitment looks a rather sad route to follow.
The Ramsey-sentence approach preserves observations, but eliminates unobservables [Ladyman/Ross]
     Full Idea: If one replaces the assertions of a first-order theory with its Ramsey sentence (giving a quantified predicate variable for a theoretical term), the observational consequences are carried over, but direct reference to unobservables is eliminated.
     From: J Ladyman / D Ross (Every Thing Must Go [2007], 2.4.1)
     A reaction: Thus this rewriting of theories is popular with empiricists, and this draws attention to the way you can change the ontological commitments simply by paraphrase. ...However, see Idea 14922.
The Ramsey sentence describes theoretical entities; it skips reference, but doesn't eliminate it [Ladyman/Ross]
     Full Idea: It is a mistake to think that the Ramsey sentence allows us to eliminate theoretical entities, for it still states that they exist. It is just that they are referred to not directly, by means of theoretical terms, but by description.
     From: J Ladyman / D Ross (Every Thing Must Go [2007], 2.4.1)