 Stanford concedes that present theories are not transiently underdetermined by the theoretical alternatives we have actually developed and considered to date: we think that our own scientific theories are considerably better confirmed by the evidence than any rivals we have actually produced. The central question, he argues, is whether we should believe that there are well confirmed alternatives to our best scientific theories that are presently unconceived by us. And the primary reason we should believe that there are, he claims, is the long history of repeated transient underdetermination by previously unconceived alternatives across the course of scientific inquiry. In the progression from Aristotelian to Cartesian to Newtonian to contemporary mechanical theories, for instance, the evidence available at the time each earlier theory dominated the practice of its day also offered compelling support for each of the later alternatives (unconceived at the time) that would ultimately come to displace it. Stanford’s “New Induction” over the history of science claims that this situation is typical; that is, that “we have, throughout the history of scientific inquiry and in virtually every scientific field, repeatedly occupied an epistemic position in which we could conceive of only one or a few theories that were well confirmed by the available evidence, while subsequent inquiry would routinely (if not invariably) reveal further, radically distinct alternatives as well confirmed by the previously available evidence as those we were inclined to accept on the strength of that evidence” (2006, 19). In other words, Stanford claims that in the past we have repeatedly failed to exhaust the space of fundamentally distinct theoretical possibilities that were well confirmed by the existing evidence, and that we have every reason to believe that we are probably also failing to exhaust the space of such alternatives that are well confirmed by the evidence we have at present. Much of the rest of his case is taken up with discussing historical examples illustrating that earlier scientists did not simply ignore or dismiss, but instead genuinely failed to conceive of the serious, fundamentally distinct theoretical possibilities that would ultimately come to displace the theories they defended, only to be displaced in turn by others that were similarly unconceived at the time. He concludes that “the history of scientific inquiry itself offers a straightforward rationale for thinking that there typically are alternatives to our best theories equally well confirmed by the evidence, even when we are unable to conceive of them at the time” (2006, 20; for reservations and criticisms concerning this line of argument, see Magnus 2006, 2010; Godfrey-Smith 2008; Chakravartty 2008; Devitt 2011; Ruhmkorff 2011; Lyons 2013). Stanford concedes, however, that the historical record can offer only fallible evidence of a distinctive, general problem of contrastive scientific underdetermination, rather than the kind of deductive proof that champions of the case from empirical equivalents have typically sought. Thus, claims and arguments about the various forms that underdetermination may take, their causes and consequences, and the further significance they hold for the scientific enterprise as a whole continue to evolve in the light of ongoing controversy, and the underdetermination of scientific theory by evidence remains very much a live and unresolved issue in the philosophy of science.