Argument Formalizer

Gettier, Case I

Edmund L. Gettier, "Is Justified True Belief Knowledge?", Analysis 23(6), 1963

Case I as a counterexample

valid

  1. Smith is justified in believing that the man who will get the job has ten coins in his pocket.

  2. It is true that the man who will get the job has ten coins in his pocket.

  3. Smith believes that the man who will get the job has ten coins in his pocket.

  4. Smith does not know that the man who will get the job has ten coins in his pocket.

  5. If [1] and [2] and [3] and [4], then there is a case in which a subject has a justified true belief that P but does not know that P.

  6. Therefore, there is a case in which a subject has a justified true belief that P but does not know that P. [1,2,3,4,5]

  7. If there is a case in which a subject has a justified true belief that P but does not know that P, then justified true belief is not sufficient for knowledge.

  8. Therefore, justified true belief is not sufficient for knowledge. [6,7]

Editor's note

The live tool could not complete this passage: its repair stage failed output validation on both attempts and the run failed closed, so no artifact exists yet. The argument shown is a hand-authored reconstruction that passed the deterministic syntax and transparent-entailment gates. It will be replaced by a tool artifact when a run succeeds. Textbook reading: Case I satisfies all three JTB conditions for proposition (e) while Smith fails to know (e), so the conditions are not jointly sufficient. The reconstruction states the four facts of the case and the sufficiency claim they refute; Gettier's own text leaves the final generalisation implicit.