 Sense determination: A constant \(c\) is characterizable by rules \(R\) iff its being governed by \(R\) suffices to fix its sense: that is, one can grasp the sense of \(c\) simply by learning that it is governed by \(R\) (Popper 1946–7, 1947; Kneale 1956, 254–5; Peacocke 1987; Hodes 2004, 135).