 Structural realism was independently developed in the 1970s by Grover Maxwell (1970a, 1970b) in an attempt to show that the Ramsey-sentence approach to theories need not lead to instrumentalism. Ramsey-sentences go back to a seminal idea by Frank Ramsey (1929). To get the Ramsey-sentence \(^{R}T\) of a (finitely axiomatisable) theory T we conjoin the axioms of T in a single sentence, replace all theoretical predicates with distinct variables \(u_i\), and bind these variables by placing an equal number of existential quantifiers \(\exists u_i\) in front of the resulting formula. Suppose that the theory T is represented as T (\(t_1\),…, \(t_n\); \(o_1\),…, \(o_m\)), where T is a purely logical \(m+n\)-predicate. The Ramsey-sentence \(^{R}T\) of T is: