Not Every Truth Can Be Known (at least, not all at once)

Greg Restall*

*Corresponding author for this work

Research output: Chapter in Book/Report/Conference proceedingChapter

1 Citation (Scopus)


According to the 'knowability thesis', every truth is knowable. Fitch's paradox refutes the knowability thesis by showing that if we are not omniscient, then not only are some truths not known, but there are some truths that are not knowable. This chapter proposes a weakening of the knowability thesis (called the 'conjunctive knowability thesis') to the effect that for every truth p there is a collection of truths such that (i) each of them is knowable and (ii) their conjunction is equivalent to p. It shows that the conjunctive knowability thesis avoids triviality arguments against it, and that it fares very differently depending on another thesis connecting knowledge and possibility. If there are two propositions, inconsistent with one another, but both knowable, then the conjunctive knowability thesis is trivially true. On the other hand, if knowability entails truth, the conjunctive knowability thesis is coherent, but only if the logic of possibility is weak.

Original languageEnglish
Title of host publicationNew Essays on the Knowability Paradox
PublisherOxford University Press
ISBN (Electronic)9780191713972
ISBN (Print)9780199285495
Publication statusPublished - 1 Sept 2010


  • Conjunctive knowability thesis
  • Knowability paradox
  • Knowability thesis
  • Truth


Dive into the research topics of 'Not Every Truth Can Be Known (at least, not all at once)'. Together they form a unique fingerprint.

Cite this