¿Una creencia verdadera justificada es conocimiento? / Is Justified True Belief Knowledge?

The paper addresses the classic question in epistemology: Is justified true belief (JTB) sufficient for knowledge? Gettier examines standard analyses that define knowledge as a belief that is true and justified. He aims to show that, even when a subject holds a belief that is both true and justified, it may still fail to constitute knowledge. The purpose is to challenge the sufficiency of JTB by presenting counterexamples, thereby motivating a reassessment of the concept of knowledge and the conditions under which we ascribe it.

The paper references historical and contemporary formulations of knowledge as JTB. It notes Plato’s discussion of true belief with an account (Theaetetus 201; Meno 98) as a precursor to the tripartite analysis. It also cites mid-20th-century accounts: R. M. Chisholm’s conditions (acceptance, adequate evidence, truth) and A. J. Ayer’s conditions (truth, being sure, right to be sure). These serve as targets for the counterexamples, with Gettier indicating that his argument undermines these formulations when their justificatory components are understood in the usual sense.

Gettier employs conceptual analysis and constructed thought experiments. He assumes two points: (1) a person can be justified in believing a proposition that is in fact false; (2) justification is closed under known entailment (if S is justified in believing P, and P entails Q, and S deduces and accepts Q from P, then S is justified in believing Q). Using these, he presents two cases:

• Case I (Coins and the job): Smith has strong evidence that Jones will get a job and that Jones has ten coins; he infers that the man who will get the job has ten coins. Unknown to Smith, Smith himself will get the job and has ten coins. Smith’s belief is true and justified but not knowledge.
• Case II (Ford and Brown’s location): Smith has strong evidence that Jones owns a Ford. He forms disjunctions with arbitrary locations of Brown (e.g., either Jones owns a Ford or Brown is in Barcelona), deduced from his evidence. In fact, Jones does not own a Ford, but by coincidence Brown is in Barcelona, making that disjunction true. Smith’s belief is true and justified but not knowledge. The method shows that meeting truth, belief, and justification does not guarantee knowledge.

• The tripartite analysis of knowledge as justified true belief fails to provide sufficient conditions for knowledge: there are cases where (i) P is true, (ii) S believes P, and (iii) S is justified in believing P, yet S does not know P.
• Case I demonstrates a justified true belief derived from a false lemma yielding a true conclusion that the subject does not know.
• Case II demonstrates a justified true belief in a true disjunction where the justification connects to the false disjunct, and the truth of the belief is due to an unrelated, coincidental fact.
• The same reasoning undermines variants by Chisholm (acceptance + adequate evidence + truth) and Ayer (truth + being sure + right to be sure), when their justificatory notions stand in for justification.

The counterexamples directly answer the research question by showing that justified true belief can occur without knowledge, thereby refuting the sufficiency of JTB. They reveal a gap between justification and truth that can be bridged accidentally or via false intermediate beliefs, which our epistemic intuitions do not count as knowledge. This challenges prevailing analyses and highlights the need for additional conditions beyond JTB to exclude luck and false lemmas. The findings are significant for epistemology, as they prompt revisions to theories of knowledge and encourage the development of more robust accounts that block Gettier-type luck.

The paper’s main contribution is to demonstrate, through two clear cases, that the traditional analysis of knowledge as justified true belief does not provide sufficient conditions for knowledge. It also shows that closely related formulations by Chisholm and Ayer fail for the same reason. Future work is suggested implicitly: articulate and defend additional conditions to supplement JTB (e.g., constraints preventing reliance on false premises or epistemic luck), and refine the concept of justification or knowledge to avoid Gettier-type counterexamples.

The argument is brief and relies on stylized thought experiments and specific assumptions about justification (including closure under entailment) and the possibility of justified false beliefs. It does not offer a positive replacement theory of knowledge or engage with alternative conceptions of justification or knowledge that might resist the cases. The scope is limited to showing insufficiency, not providing necessary and sufficient conditions.