 Thus Zahar proposed that a fact is novel “if it did not belong to the problem-situation which governed the construction of the hypothesis” (1973: 103). This form of novelty has been deemed ‘problem-novelty’ (Gardner 1982: 2). But in the same paper Zahar purports to exemplify this concept of novelty by referring to the case in which Einstein did not use the known behavior of Mercury’s perihelion in constructing his theory of  relativity.[3]  Gardner notes that this latter conception of novelty, which he deemed ‘use-novelty’, is distinct from problem-novelty (Gardner 1982: 3). Evidence is use-novel for T if T was not built to fit that evidence (whether or not it was part of the relevant ‘problem-situation’ the theory was intended to address). In subsequent literature, the so-called heuristic conception of novelty has been identified with use-novelty—it was further articulated in Worrall 1978 and  1985.[4] 