Fallibilism (from medieval Latin fallibilis, "liable to err") is the philosophical principle that human beings could be wrong about their beliefs, expectations, or their understanding of the world, and yet still be justified in holding their incorrect beliefs. In the most commonly used sense of the term, this consists in being open to new evidence that would disprove some previously held position or belief, and in the recognition that "any claim justiﬁed today may need to be revised or withdrawn in light of new evidence, new arguments, and new experiences." This position is taken for granted in the natural sciences.
In another sense, it refers to the consciousness of "the degree to which our interpretations, valuations, our practices, and traditions are temporally indexed" and subject to (possibly arbitrary) historical flux and change. Such "time-responsive" fallibilism consists in an openness to the confirmation of a possibility that one anticipates or expects in the future.
Some fallibilists argue that absolute certainty about knowledge is impossible. As a formal doctrine, fallibilism is most strongly associated with Charles Sanders Peirce, John Dewey, and other pragmatists, who use it in their attacks on foundationalism. However, it is already present in the views of ancient philosophers that were adherents of philosophical skepticism, including the philosopher Pyrrho. Fallibilism is related to Pyrrhonistic Skepticism, in that Pyrrhonists of history are sometimes referred to as fallibilists, and modern fallibilists as Pyrrhonists.
Another proponent of fallibilism is Karl Popper, who builds his theory of knowledge, critical rationalism, on falsifiability. Fallibilism has been employed by Willard Van Orman Quine to attack, among other things, the distinction between analytic and synthetic statements.
Unlike scepticism, fallibilism does not imply the need to abandon our knowledge—we needn't have logically conclusive justifications for what we know. Rather, it is an admission that, because empirical knowledge can be revised by further observation, any of the things we take as knowledge might possibly turn out to be false. Some fallibilists make an exception for things that are axiomatically true (such as mathematical and logical knowledge). Others remain fallibilists about these as well, on the basis that, even if these axiomatic systems are in a sense infallible, we are still capable of error when working with these systems. The critical rationalist Hans Albert argues that it is impossible to prove any truth with certainty, even in logic and mathematics. This argument is called the Münchhausen Trilemma.
Moral fallibilism 
Moral fallibilism is a specific subset of the broader epistemological fallibilism outlined above. In the debate between moral subjectivism and moral objectivism, moral fallibilism holds out a third plausible stance: that objectively true moral standards may exist, but that they cannot be reliably or conclusively determined by humans. This avoids the problems associated with the flexibility of subjectivism by retaining the idea that morality is not a matter of mere opinion, whilst accounting for the conflict between differing objective moralities. Notable proponents of such views are Isaiah Berlin (value pluralism) and Bernard Williams (perspectivism).
Some suggest that epistemological fallibilism claims absolute knowledge as part of an axiom. Essentially, the statement "This much is certain: nothing is certain" claims the knowledge that: there is no knowledge; thus arriving at a contradiction.
Karl Popper has suggested the methodological approach that the statement be provisionally taken as true until another statement is presented that, after surviving a critical discussion, is accepted as certain. The acceptance of this statement as certain would then be sufficient to reject fallibilism.
See also 
- Nikolas Kompridis, "Two kinds of fallibilism", Critique and Disclosure (Cambridge: MIT Press, 2006), 180.
- Kuhn, Thomas S. The Structure of Scientific Revolutions. 3rd ed. Chicago, IL: University of Chicago Press, 1996
- Nikolas Kompridis, "Two kinds of fallibilism", Critique and Disclosure (Cambridge: MIT Press, 2006), 181.
- Powell, T.C. (2001), Fallibilism and Organizational Research: The Third Epistemology, Journal of Management Research, 4, 201-219.
- Thorsrud, Harold (2004), Ancient Greek Skepticism, Internet Encyclopedia of Philosophy.
Further reading 
- Charles S. Peirce: Selected Writings, ed. by Philip P. Wiener (Dover, 1980)
- Charles S. Peirce and the Philosophy of Science, ed. by Edward C. Moore (Alabama, 1993)
- Traktat über kritische Vernunft, Hans Albert (Tübingen: Mohr, 1968. 5th ed. 1991)
- The Open Society and Its Enemies, Karl Popper (1945) Vol 1 ISBN 0-415-29063-5, Vol 2 ISBN 0-415-29063-5