Fallibilism

Lore & Background

Fallibilism originated as a response to foundationalism, coined by American philosopher Charles Sanders Peirce. Theorists following Austrian-British philosopher Karl Popper also refer to fallibilism as the notion that knowledge might turn out to be false. Fallibilism is said to imply corrigibilism, the principle that propositions are open to revision. According to philosopher Scott F. Aikin, fallibilism cannot properly function in the absence of infinite regress. Philosophy professor Elizabeth F. Cooke holds that fallibilism embraces uncertainty, and that infinite regress and infinite progress are not unfortunate limitations but necessary antecedents for knowledge acquisition. Fallibilism has been employed by philosopher Willard V. O. Quine to attack the distinction between analytic and synthetic statements. British philosopher Susan Haack argues that the nature of fallibilism is often misunderstood because people confuse fallible propositions with fallible agents.

Reader's Guide

Fallibilism is a central concept in epistemology, asserting that no belief or knowledge is certain and that all propositions are open to revision. It was introduced by Charles Sanders Peirce as a challenge to foundationalism and later developed by Karl Popper within critical rationalism. The principle underpins much of modern philosophy of science, where scientific claims are regarded as provisional and falsifiable. Fallibilism is distinct from skepticism, as it does not deny the possibility of knowledge but rather the certainty of it. Nearly all contemporary philosophers are fallibilists in some sense, though some argue for infallibilist knowledge. The concept has been applied to logic, mathematics, and the critique of analytic-synthetic distinctions. Its legacy includes shaping debates about justification, the regress problem, and the nature of scientific progress.

Did You Know?

• The term 'fallibilism' was coined in the late 19th century by American philosopher Charles Sanders Peirce.
• Fallibilism is said to imply corrigibilism, the principle that propositions are open to revision.
• According to philosopher Scott F. Aikin, fallibilism cannot properly function in the absence of infinite regress.
• Fallibilism should not be confused with local or global skepticism.

Origins and the Core Commitment

The term fallibilism traces its etymology to the Medieval Latin word fallibilis, which simply means 'liable to error.' At its heart, the principle holds that a person may rationally accept a proposition even when that proposition cannot be demonstrated with absolute certainty, and that neither what we call knowledge nor what we call belief is beyond the possibility of being wrong. The label itself was minted in the late nineteenth century by the American thinker Charles Sanders Peirce, who introduced it as a direct counter to foundationalism. Later, the Austrian-British philosopher Karl Popper reframed the idea in his own idiom, describing it as the recognition that any body of knowledge might ultimately prove to be false. A natural corollary of fallibilism is corrigibilism, the insistence that every accepted claim remains open to revision. In everyday philosophical discourse, fallibilism is most often set in direct opposition to its mirror image, infallibilism, the conviction that some truths stand beyond any possibility of doubt.

Infinite Regress, Infinite Progress, and the Architecture of Inquiry

Philosopher Scott F. Aikin has argued that fallibilism simply cannot operate without the concept of infinite regress, a puzzle usually traced back to the Pyrrhonist Agrippa. The reasoning is straightforward: every proposition demands a justification, and that justification in turn demands its own, producing an endless chain. This regress is tightly woven into the problem of the criterion and forms one horn of the Münchhausen trilemma. Familiar illustrations include the cosmological argument, the image of turtles stacked on turtles, and the simulation hypothesis. On the other side of the coin, the English philosopher Thomas Hobbes, writing in the seventeenth century, introduced the notion of 'infinite progress' to capture humanity's restless drive toward perfection, a theme later expanded by Leibniz, Wolff, and Kant, who even mused that an immortal species might eventually perfect its capacities. Elizabeth F. Cooke, a philosophy professor, contends that both regress and progress are not defects in human cognition but essential preconditions for acquiring knowledge, enabling us to lead functional and meaningful lives.

Critical Rationalism and the Falsification Tradition

In the mid-twentieth century, a wave of philosophers turned their attention to the foundations of logical positivism. For Popper, falsifiability was the litmus test separating science from non-science, and every scientific claim was inherently provisional, always open to revision when new evidence appeared. He framed critical rationalism as both a normative and a methodological account of how mind-independent, objective knowledge ought to function. The Hungarian philosopher Imre Lakatos extended this project by recasting the demarcation problem as one of normative appraisal, yet he also pressed Popper on a crucial gap: critical rationalism explains how individual theories can be falsified but leaves unexplained how the falsification principle itself can be justified without smuggling in induction. Popper refused to concede the point. Quine wielded fallibilism to dissolve the analytic-synthetic divide, while Susan Haack warned that people routinely conflate fallible propositions with fallible agents, insisting that logic itself is revisable. Hans Albert went further, maintaining that no truth in logic or mathematics can be proven with certainty.

Not Skepticism: Fallibilism's Distinct Identity and Broad Consensus

A common misreading is to equate fallibilism with skepticism, whether local or global, the position that some or all categories of knowledge are simply unattainable. Popper himself was emphatic on this point: the fact that our knowledge is fallible, that every claim is in a sense a conjecture that has survived the harshest testing, must not be wielded as ammunition for relativism or for the claim that the choice between competing theories is arbitrary. From the mere possibility of error, it does not follow that learning is impossible, that we cannot inch closer to the truth, or that knowledge cannot grow. The technical distinction is precise: fallibilism holds that legitimate epistemic justifications can, in principle, yield false beliefs, whereas academic skepticism asserts that no legitimate justifications exist at all, a position known as acatalepsy. Fallibilism also differs from epoché, the Pyrrhonian practice of suspending judgment altogether. In contemporary philosophy, the consensus leans heavily toward fallibilism in some form; very few thinkers insist that knowledge demands absolute certainty, and even fewer would deny that scientific claims remain subject to revision.