Infallibilism should not be confused with the universally accepted view that a proposition P must be true in order for someone to know that P. Instead, the infallibilist holds that a person who knows P could not have all of the same evidence (or justification) that one currently has if P were false, and therefore that one's evidence/justification offers a guarantee of the truth of P. Thus, in cases where a person could have held the same true belief P with the same level of evidence (or justification) and still been wrong, the infallibilist holds that the person does not know P. The infallibilist defines knowledge in the following way:[1] A person (henceforth S) knows that a proposition (henceforth P) is true if and only if: According to the infallibilist, fallible beliefs may be rationally justified, but they do not rise to the level of knowledge unless their truth is absolutely certain given one's evidence.
[2][3] René Descartes, an early proponent of infallibilism, argued, "my reason convinces me that I ought not the less carefully to withhold belief from what is not entirely certain and indubitable, than from what is manifestly false".
[5] Broad consensus notwithstanding, some contemporary philosophers have presented arguments in defense of infallibilism and have therefore come to reject fallibilism.
For instance, Mark Kaplan defends such a view in a 2006 paper entitled "If You Know You Can't Be Wrong".
[6] Other notable contemporary proponents of infallibilism include Andrew Moon, Julien Dutant, and Matthew Benton.