  Or, in Harman’s pithier formulation: “Count as logic only as much as you have to” (Harman 1972, 79). Warmbrod uses this constraint to argue that the theory of identity is not part of logic, on the grounds that it is not needed to do the job he has identified for logic: “[w]e can systematize the same sets of sentences by recognizing only the truth-functional connectives and first-order quantifiers as constants, treating ‘=’ as an ordinary predicate, and adopting  appropriate axioms for identity” (521; cf. Quine 1986, 63, 1980, 28). On similar grounds, both Harman and Warmbrod argue that modal operators should not be considered part of  logic.[24]  Their point is not that identity or modal operators lack some feature that the first-order quantifiers and truth-functional operators possess, but merely that, since we can get by without taking these notions to be part of our logic, we should. Warmbrod and Tharp even explore the possibility of taking truth-functional logic to be the whole of logic and viewing quantification theory as a non-logical theory (Warmbrod 1999, 525; Tharp 1975, 18), though both reject this idea on pragmatic grounds.