Jeffrey Ketland


Since F.P. Ramsey's introduction of the idea (Ramsey 1929, “Theories”), a number of philosophers have suggested that the cognitive content of a scientific theory should be given by its Ramsey sentence. Ramsification provides a means of eliminating theoretical predicates without having to provide an explicit definition, and is therefore attractive to philosophers of a positivist inclination. However, the Ramsey sentence of a theory is weaker than the theory itself. Demopoulos & Friedman (1985, "Critical Notice: Bertrand Russell's The Analysis of Matter: Its Historical Context and Contemporary Interest", Philosophy of Science 52) were the first to introduce the so-called Newman objection to Ramsey sentence approaches to eliminating theoretical predicates, based on Newman's 1928 critique of Russell's structuralism. Demopoulos & Friedman pointed out that, roughly, the truth of the Ramsey sentence of a theory is equivalent to its empirical adequacy and perhaps a cardinality condition on the external world. The technical details of one version of this objection were set out in Ketland 2004 (“Empirical adequacy and ramsification”, BJPS). Roughly, one obtains theorems of the form, "the Ramsey sentence of a theory T is true if and only T has a model with certain properties". The main result of Ketland 2004 is one such theorem. However, there are in fact several inequivalent ways to analyse the formalization of scientific theories, the notion of “empirical adequacy” and the construction of the Ramsey sentence. (For example, whether the theory is 16 formulated in a one-sorted or many-sorted language; whether un-ramsified predicates are allowed to have unobservable objects in their field; etc.) This paper will survey several of these alternatives, and give corresponding results expressing the truth conditions of Ramsey sentences.


20th century philosophy; logic; philosophy; Wittgenstein Ludwig; formal language; logic; mathematics; Ramsey Frank; structuralism

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