Barbershop paradox

The barbershop paradox was proposed by Lewis Carroll in a three-page essay titled "A Logical Paradox", which appeared in the July 1894 issue of Mind. The name comes from the "ornamental" short story that Carroll uses in the article to illustrate the paradox. It existed previously in several alternative forms in his writing and correspondence, not always involving a barbershop. Carroll described it as illustrating "a very real difficulty in the Theory of Hypotheticals".[1] From the viewpoint of modern logic, it is seen not so much as a paradox than as a simple logical error. It is of interest now mainly as an episode in the development of algebraic logical methods when these were not so widely understood (even among logicians), although the problem continues to be discussed in relation to theories of implication and modal logic.[2]

  1. ^ Carroll, Lewis (July 1894). "A Logical Paradox". Mind. 3 (11): 436–438.
  2. ^ Carroll, Lewis (1977). Bartley, William Warren (ed.). Symbolic Logic, Parts I and II. Harvester Press. ISBN 0855279842.