Interplay Between Truth and Justification in Knowledge

When we say we “know” something, we usually mean more than just believing it – we expect our belief to be true and backed by good reasons. But here’s where epistemology gets interesting: what exactly is the relationship between having good reasons (justification) and actually being right (truth)? Are they two sides of the same coin, or can they come apart? This question sits at the heart of modern epistemology, and its answer has significant implications for how we understand knowledge itself.

The classical picture: justified true belief 🔗

The dominant account of knowledge in Western philosophy, traced back to Plato’s dialogues Meno and Theaetetus, defines knowledge as justified true belief (JTB). According to this model, for you to know a proposition, three conditions must all be satisfied: the proposition must be true, you must believe it, and your belief must be justified – meaning it is supported by evidence, sound reasoning, or reliable processes rather than mere guesswork.

The justification condition carries considerable weight here. As the Internet Encyclopedia of Philosophy explains, a lucky guess cannot constitute knowledge, and neither can misinformation or faulty reasoning – even if they happen to lead you to a true belief. Justification is what separates knowledge from accidentally correct opinion. So far, this all sounds tidy: you have reasons, those reasons track reality, and that tracking just is what makes a belief count as knowledge. But the relationship between truth and justification is not as seamless as it first appears.

Truth and justification as independent conditions 🔗

It is tempting to assume that justification and truth are tightly linked – that if your belief is well supported, it is more likely to be correct, and if it is correct, it probably was well supported. But epistemologists have shown that truth and justification are actually two independent conditions on beliefs. The fact that a belief is true tells you nothing about whether it was justified – that depends entirely on how the belief was formed. Conversely, a belief can be thoroughly justified and still turn out to be false.

Consider how this plays out. Two people can hold the same true belief – say, that a particular drug is safe – but one has read the clinical trial literature carefully, while the other simply trusts an anecdote from a friend. Both are right, but only one is justified. Now flip the scenario: a physician who has studied all available evidence might believe a drug is safe, only for new research to later reveal a rare side effect. The physician’s belief was justified but false. These everyday examples reveal that justification and truth, while related, do not guarantee each other.

Epistemic justification is therefore best understood as truth-conducive: it is whatever makes a belief more rationally well-supported and more likely to be true – but it does not make truth certain. As the IEP article on epistemic justification puts it, justification is the right standing of a person’s beliefs with respect to knowledge, and that standing is evaluated by how beliefs are formed and held, not merely by whether they happen to be correct.

Fallibilism: justification without guarantees 🔗

Fallibilism is the philosophical position that captures this gap most directly. According to the Internet Encyclopedia of Philosophy, fallibilism is the epistemological thesis that no belief can ever be rationally supported or justified in a completely conclusive way – there always remains a possible doubt as to the truth of any belief. The term was coined by the American philosopher Charles Sanders Peirce in the nineteenth century, though the underlying insight long predates him.

This does not mean all beliefs are false, or that we can never know anything. Fallibilism claims that legitimate epistemic justifications can lead to false beliefs – which is distinct from the skeptical view that no legitimate justification exists at all. Most contemporary epistemologists are fallibilists precisely because the alternative – infallibilism, the demand that knowledge requires absolute certainty – would make knowledge nearly impossible to attain. Demanding infallibility would prevent us from knowing almost anything, since almost no belief can be supported in a way that eliminates all conceivable doubt.

Fallibilism, then, is a realistic acknowledgment of human cognitive limits. It says that we can have knowledge on the basis of good but defeasible justification – justification that does not guarantee truth, yet is still sufficient for knowledge when other conditions are met.

The Gettier problem: when justification and truth still aren’t enough 🔗

If fallibilism shows that justification does not guarantee truth, the Gettier problem shows something even more striking: that justification and truth together do not guarantee knowledge. In 1963, American philosopher Edmund Gettier published a now-legendary three-page paper, “Is Justified True Belief Knowledge?”, presenting counterexamples to the JTB account that fundamentally altered the character of contemporary epistemology.

Gettier’s cases work like this: a true belief is inferred from a justified false belief, resulting in a belief that meets all three JTB conditions – yet intuitively does not count as knowledge. In his first case, Smith has strong evidence (including testimony from his employer) that Jones will get a job, and Smith also knows Jones has ten coins in his pocket. Smith concludes: “The man who gets the job will have ten coins in his pocket.” As it happens, Smith – not Jones – gets the job, and Smith also has ten coins in his own pocket. So Smith’s belief is true and justified, but it is true entirely by coincidence, not because of the reasoning that led to it.

A simpler illustration: imagine you see someone outside who strongly resembles your father, and you form the justified belief that your father is shoveling snow. In fact, your father is shoveling snow – but on the other side of the house, out of view. The person you saw was actually a neighbor. Your belief is justified, it is true, but you did not know your father was shoveling snow, because the truth of your belief was entirely disconnected from the evidence that justified it.

Gettier-type counterexamples challenge the long-held JTB account of knowledge by revealing that justification and truth can come together in the right way for entirely the wrong reasons – through epistemic luck. This matters because it shows the relationship between justification and truth is not just imperfect (as fallibilism says), but also fragile in a structural sense: even when they co-occur, their co-occurrence may be accidental in a way that undermines knowledge.

What fallibilism means for the role of justification 🔗

The fallibilist insight, sharpened by the Gettier problem, pushes epistemologists to rethink what justification is actually doing in the theory of knowledge. If justification neither guarantees truth nor, by itself, guarantees knowledge even when truth is present, what is it for?

The most defensible answer is that justification remains a necessary condition for knowledge – but it is not sufficient. Epistemic justification provides a crucial knowledge-contributing link between a person and a person’s believing that a proposition is true. Without it, true beliefs are merely lucky guesses. With it, a belief is responsive to evidence and reasoning, even if it can still be wrong.

Fallibilism invites a more humble and dynamic conception of knowledge. Fallibilist epistemologists see themselves as thinking about knowledge and justification in a comparatively realistic way – recognizing the fallibilist realities of human cognitive capacities, while still allowing fallible people to have knowledge and justified beliefs. Knowledge is not a permanent, unrevailable possession; it is provisional. New evidence can undercut previously justified beliefs. Scientific theories once accepted as knowledge – Newtonian mechanics being the classic example – were later revised in light of better evidence. Physicists in the late 1700s were justified in believing Newtonian physics was true, even though Einstein would eventually show they were wrong. Their justification was real; it just turned out to be fallible.

Justification aims at truth but cannot deliver it with certainty 🔗

One of the most important insights in this discussion is that justification is truth-directed without being truth-guaranteeing. Epistemic justification is whatever would make a belief more, rather than less, rationally well supported – and this rationality is meant to be truth-directed. When evidence supports a belief, it supports it as true – but the support is never conclusive. This is the essence of the gap between subjective justification and objective truth.

Philosophers distinguish two broad kinds of approaches to understanding this gap. Internalists hold that justification depends entirely on the believer’s own mental states – their evidence, reasoning, and perspective. Externalists argue that justification also depends on factors outside the believer’s perspective, such as whether the cognitive processes producing the belief are reliably connected to truth in the actual world. The truth-conducive conception of justification – holding that a belief is justified when there is sufficient evidence that the belief is at least likely to be true – corresponds to epistemic externalism. Externalist accounts like reliabilism attempt to close the gap between justification and truth by requiring that justified beliefs be produced by belief-forming mechanisms that reliably yield true beliefs.

Fallibilism is not skepticism 🔗

A common misreading of fallibilism treats it as a form of skepticism – the view that we cannot know anything. This is a mistake. Fallibilism should not be confused with local or global skepticism, which holds that some or all types of knowledge are unattainable. Fallibilism accepts that knowledge is possible; it simply denies that knowledge requires certainty. The fallibilist says: we can know things, but our knowing is always open to revision in the light of new evidence. This is not a counsel of despair – it is an accurate description of how inquiry actually works, in both science and everyday life.

As a methodological proposal, fallibilism constitutes a salutary warning: do not treat any claim as so certainly established that it is forever immune to revision. This attitude is the engine of scientific progress and intellectual honesty. It is precisely because scientists treat their best theories as revisable – not because they consider them worthless – that science advances.

Bridging the subjective and the objective 🔗

At its core, the relationship between truth and justification is about the relationship between the subjective and the objective. Truth is a property of propositions as they relate to the world – it is objective and mind-independent. Justification is a property of beliefs as they relate to a person’s evidence and reasoning – it is, at least partly, subjective and perspective-dependent. Because of luck, a belief can be unjustified yet true; and because of human fallibility, a belief can be justified yet false – making truth and justification two independent conditions of belief.

Justification is the bridge we build between these two domains. It is our epistemic tool for trying to align what we believe with what is actually the case. But as fallibilism makes clear, even the best-built bridge can fail – evidence can mislead, reasoning can have hidden flaws, and the world can be stranger than our best theories anticipate. Recognizing this is not a reason to stop building bridges; it is a reason to build them more carefully, remain open to inspecting them, and be willing to rebuild when they prove inadequate.

This is ultimately what modern epistemology’s treatment of truth and justification teaches us: knowledge is not a destination at which we finally arrive with certainty, but an ongoing, self-correcting process of bringing our justified beliefs into closer alignment with truth.

What do you think? If justification can never fully guarantee truth, does that change the way you evaluate the beliefs you feel most confident about? And given that even well-justified scientific theories have turned out to be false, how should we decide which justified beliefs to act on?

References

1. https://iep.utm.edu/epistemo/
2. https://iep.utm.edu/epi-just/
3. https://iep.utm.edu/fallibil/
4. https://en.wikipedia.org/wiki/Fallibilism
5. https://philarchive.org/archive/HANSFA-5
6. https://iep.utm.edu/gettier/
7. https://plato.stanford.edu/entries/knowledge-analysis/
8. https://learn.academy4sc.org/video/the-gettier-problem-true-justified-belief-without-knowledge/
9. https://en.wikipedia.org/wiki/Gettier_problem
10. https://press.rebus.community/intro-to-phil-epistemology/chapter/epistemic-justification/
11. https://en.wikipedia.org/wiki/Justification_(epistemology)
12. https://en.unav.edu/web/ciencia-razon-y-fe/conocimiento-humano-fiabilidad-y-falibilismo