 One especially important reaction to concerns about the alleged underdetermination of theory by data gives rise to another leading antirealist argument. This reaction is to reject one of the key premises of the argument from underdetermination, viz. that evidence for belief in a theory is exhausted by the empirical data. Many realists contend that other considerations—most prominently, explanatory considerations—play an evidential role in scientific inference. If this is so, then even if one were to grant the idea that all theories have empirically equivalent rivals, this would not entail underdetermination, for the explanatory superiority of one in particular may determine a choice (Laudan 1990; Day &amp; Botterill 2008). This is a specific exemplification of a form of reasoning by which “we infer what would, if true, provide the best explanation of [the] evidence” (Lipton [1991] 2004: 1). To put a realist-sounding spin on it: 