masked-man fallacy

Noun

masked man fallacy (plural masked man fallacies)

1. A fallacy of inferring that since one knows (or does not know) something by one description, one must know (or not know) it by another, as in "I know who my father is. I do not know who the masked man is. Therefore, my father is not the masked man."
   • That is to say, one cannot infer from one's subjective state of certainty and uncertainty about two propositions, to the objective connection or lack of connection between them; but it is just such an inference that Descartes seems to be making about himself and his body, and which gives his...1978, Bernard Williams, Descartes: The Project of Pure Enquiry, New York: Routledge, published 2005, page 97

   Synonyms:

   intensional fallacy