 John Worrall has been an important contributor to the predictivism literature from the 1970s until the present time. He was, along with Elie Zahar, one of the early proponents of the significance of heuristic novelty (e.g., Worrall 1978, 1985). In his more recent work (cf. his 1989, 2002, 2005, 2006, 2010, 2014; also Scerri &amp; Worrall 2001) Worrall has laid out a detailed theory of predictivism that, while sometimes presented in heuristic terms, is “at root a logical theory of confirmation” (2005: 819)—it is thus a weak heuristic account that takes use-novelty of evidence to be symptomatic of underlying logical features that establish strong confirmation of theory. 