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.
Gist of Idea
There is a method for defining new scientific terms just using the terms we already understand
Source
David Lewis (How to Define Theoretical Terms [1970], Intro)
Book Reference
Lewis,David: 'Philosophical Papers Vol.1' [OUP 1983], p.78
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.