Paradox Lost pp 203-207 | Cite as

The Ravens

  • Michael Huemer


In general, the observation of an A that is B supports “All A’s are B.” Therefore, observation of a purple shoe supports “All non-black things are non-ravens.” This is logically equivalent to “All ravens are black.” So purple shoes provide evidence that all ravens are black. This seems crazy. The solution is to recognize that whether an observation of an A that is B supports “All A’s are B” or not depends upon how the observation was gathered – e.g., whether it was gathered by selecting randomly from the class of A’s, or selecting randomly from the class of B’s.


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  2. Nicod, Jean. 1930. Foundations of Geometry and Induction, tr. Philip Paul Wiener. London: Kegan Paul, Trench, Trubner & Co.Google Scholar
  3. Rescher, Nicholas. 2001. Paradoxes: Their Roots, Range, and Resolution. Chicago, IL: Open Court.Google Scholar

Copyright information

© The Author(s) 2018

Authors and Affiliations

  • Michael Huemer
    • 1
  1. 1.Philosophy DepartmentUniversity of Colorado BoulderBoulderUSA

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