Truth is normally considered a necessary condition of propositional knowledge: a person cannot know a claim that is false. However, truth alone is not sufficient because a true claim may be guessed, believed irrationally, or held only by accident.
The traditional analysis defines knowledge as justified true belief. For a subject, S, to know a proposition, P, three conditions must be satisfied:
| Condition | Role in knowledge |
|---|---|
| Belief | S must accept P; someone cannot know what they do not believe. |
| Truth | P must correspond to how reality actually is; false propositions cannot be known. |
| Justification | S must have adequate reasons or evidence for believing P. |
Truth therefore distinguishes knowledge from justified but mistaken belief. Suppose a student has strong evidence that the library closes at 5 p.m., but it actually closes at 4 p.m. The belief may be justified, yet it is not knowledge because it is false.
However, truth does not by itself turn belief into knowledge. If a student guesses that a coin will land heads and it does, the belief is true but lacks justification. Even justified true belief may be insufficient, as Gettier cases demonstrate. In such cases, a person reaches a true, justified conclusion only because of epistemic luck. This suggests that knowledge may require an additional condition, such as the absence of false assumptions, a reliable belief-forming process, or a suitable causal connection to the fact.
A key distinction is between truth and our criterion of truth. Truth concerns whether P is actually the case; justification concerns how the knower determines or supports P. Disagreement about correspondence, coherence, or pragmatic theories of truth affects how truth is understood, but does not remove its central role in propositional knowledge.
In an IB Philosophy response, define truth as a necessary condition, explain why it is not sufficient, and evaluate the justified true belief account using a clear Gettier-style counterexample. Avoid the misconception that strong justification guarantees truth.