Article

Journal of Philosophical Logic

, Volume 41, Issue 2, pp 493-503

First online:

Why the Hardest Logic Puzzle Ever Cannot Be Solved in Less than Three Questions

  • Gregory WheelerAffiliated withCENTRIA - Centre for Artificial Intelligence, The New University of Lisbon Email author 
  • , Pedro BarahonaAffiliated withCENTRIA - Centre for Artificial Intelligence, The New University of Lisbon

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Abstract

Rabern and Rabern (Analysis 68:105–112 2) and Uzquiano (Analysis 70:39–44 4) have each presented increasingly harder versions of ‘the hardest logic puzzle ever’ (Boolos The Harvard Review of Philosophy 6:62–65 1), and each has provided a two-question solution to his predecessor’s puzzle. But Uzquiano’s puzzle is different from the original and different from Rabern and Rabern’s in at least one important respect: it cannot be solved in less than three questions. In this paper we solve Uzquiano’s puzzle in three questions and show why there is no solution in two. Finally, to cement a tradition, we introduce a puzzle of our own.

Keywords

Boolos Logic puzzle Information theory