 In a justly celebrated discussion, Larry Laudan (1990) argues that the significance of such underdetermination has been greatly exaggerated. Underdetermination actually comes in a wide variety of strengths, he insists, depending on precisely what is being asserted about the character, the availability, and (most importantly) the rational defensibility of the various competing hypotheses or ways of revising our beliefs that the evidence supposedly leaves us free to accept. Laudan usefully distinguishes a number of different dimensions along which claims of underdetermination vary in strength, and he goes on to insist that those who attribute dramatic significance to the thesis that our scientific theories are underdetermined by the evidence invariably defend only the weaker versions of that thesis, while they go on to draw dire consequences and shocking morals regarding the character and status of the scientific enterprise from much stronger versions. He suggests, for instance, that Quine’s famous claim that any hypothesis can be preserved “come what may” can perhaps be defended simply as a description of what it is psychologically possible for human beings to do, but Laudan insists that in this form the thesis is simply bereft of interesting or important consequences for epistemology— the study of knowledge. The strong version of the thesis along this dimension instead asserts that it is always normatively or rationally defensible to retain any hypothesis in the light of any evidence whatsoever, but this latter, stronger version of the claim, Laudan suggests, is one for which no convincing evidence or argument has ever been offered. More generally, he insists, arguments for underdetermination turn on implausibly treating all logically possible responses to the evidence as equally justified or rationally defensible. For example, Laudan suggests that we might reasonably hold the resources of deductive logic to be insufficient to single out just one acceptable response to disconfirming evidence, but not that deductive logic plus the sorts of ampliative principles of good reasoning typically deployed in scientific contexts are insufficient to do so. Similarly, defenders of underdetermination might assert the nonuniqueness claim that for any given theory or web of beliefs there is at least one alternative that can also be reconciled with the available evidence, or the stronger egalitarian claim that all of the contraries of any given theory can be reconciled with the available evidence equally well. And the claim of such “reconciliation” itself disguises a wide range of further alternative possibilities: that our theories can be made logically compatible with any amount of disconfirming evidence (perhaps by the simple expedient of removing any claim(s) with which the evidence is in conflict), that any theory may be reformulated or revised so as to entail any piece of previously disconfirming evidence, or so as to explain previously disconfirming evidence, or that any theory can be made to be as well supported empirically by any collection of evidence as any other theory. And in all of these respects, Laudan claims, partisans have defended only the weaker forms of underdetermination while founding their further claims about and conceptions of the scientific enterprise on versions much stronger than those they have managed or even attempted to defend. 