Impurism, pragmatic encroachment, and the Argument from Principles


The Argument from Principles, the primary motivation for impurism or pragmatic encroachment theories in epistemology, is often presented as an argument for everyone—an argument that proceeds from (reasonably) harmless premises about the nature of rationally permissible action to the surprising conclusion that one’s knowledge is partly determined by one’s practical situation. This paper argues that the Argument from Principles is far from neutral, as it presupposes the falsity of one of impurism’s main competitors: epistemic contextualism. As a consequence, hybrid positions combining impurism and contextualism—positions that impurists have sometimes hinted at in the literature—are, while logically consistent, ill-motivated. Once the impurist embraces contextualism, the Argument from Principles can no longer get off the ground. The paper concludes that those who make use of the Argument from Principles are committed to an invariantist impurism and their case in support of impurism can only ever be as strong as their case against contextualism. Given recent contextualist work on the semantics of ‘knowledge’-attributions, this is likely to turn out problematic for the impurists.

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  1. 1.

    Further qualifications are necessary here, but I shall ignore them for the sake of readability. See Hawthorne and Stanley (2008) for discussion.

  2. 2.

    See Stanley (2005, p. 17) for this characterization.

  3. 3.

    To see this note that the occurrence of ‘knows’ in (KPR) is used, not mentioned, and thus takes its semantic value in the context in which (KPR) is stated or discussed, which is, in this case, the context of this paper.

  4. 4.

    Note that Fantl and McGrath are committed to (V) as well: (1) and (SUF) entail (i), and (i) and (2) entail (V):

    1. (i)

      In Low Stakes, we are permitted to use p as a premise in our practical reasoning.

  5. 5.

    See, for instance, Blome-Tillmann (2013), Cohen (2004), DeRose (2009, p. 99), Fantl and McGrath (2009, p. 50) and Hawthorne (2004, p. 85ff).

  6. 6.

    For further discussion of the relationship between contextualism, (KPR), and (V) see the following section.

  7. 7.

    Given invariantism, (KPR) entails (KPR*).

  8. 8.

    See, for instance, Blome-Tillmann (2008, 2014, ch. 4, ms).


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Correspondence to Michael Blome-Tillmann.

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Blome-Tillmann, M. Impurism, pragmatic encroachment, and the Argument from Principles. Synthese (2020).

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  • Impurism
  • Pragmatic encroachment
  • Epistemic contextualism
  • Argument from Principles
  • Knowledge Norm of Practical Reasoning