Os anulabilismos de Klein e de Swain e o problema de Gettier

Emerson Carlos Valcarenghi


In this essay, we intend to show that Peter Klein and Marshall Swain defeasibility theories do not resolve the Gettier problem. Klein postulates, to any Gettier counterexample, that there is a true proposition which, when associated with evidence-e of S, genuinely defeats the justification of p to S. Swain postulates that, to any Gettier-type counterexample, there is a true proposition which, when associated with the set of reasons-R of S, ultimately defeats the justification of S to believe p. To show that Klein an Swain proposals do not resolve that problem, this essay presents two Gettier-type counterexamples for which there are no genuine defeaters of justification of p by e to S and there are no defeaters not ultimately defeated of the justification of the belief of S that p by R. After doing that, we try to show that the obtained conclusion regarding Klein and Swain defeasibility theories can be extended to any defeasibility theory of knowledge.


Gettier problem, belief justification, defeasibility theory.

DOI: https://doi.org/10.5007/1808-1711.2010v14n2p175

Copyright (c)


Principia: an internationnal journal of epistemology
Published by NEL - Epistemology and Logic Research Group
Federal University of Santa Catarina - UFSC
Center of Philosophy and Human Sciences – CFH
Campus Reitor João David Ferreira Lima
Florianópolis, Santa Catarina - Brazil
CEP: 88040-900

 ISSN: 1414-4217
EISSN: 1808-171

e-mail: principia@contato.ufsc.br