Making The ‘Hardest Logic Puzzle Ever’ a Bit Harder

Abstract

This paper intends to propose new forms of logic puzzles by adopting a pluralist perspective. Not only can this expanded view lead to more challenging puzzles, but it also helps the understanding of novel forms of reasoning. In 1996, George Boolos published a famous puzzle, known as the ‘hardest logic puzzle ever’. This puzzle has been modified several times, and is known not to be ‘the most difficult of all logical puzzles’. I argue that modified versions of this famous puzzle can be made even harder by using non-standard logics. As a study case, I introduce a version of the puzzle based on the three-valued paraconsistent logic LFI1 and show how it can be solved in three questions, leaving the conjecture that this three-valued puzzle cannot be solved in fewer than three questions.