Main Page | See live article | Alphabetical index



A paradox is an apparently true statement that seems to lead to a logical self-contradiction, or to a situation that contradicts common intuition. The identification of a paradox based on seemingly simple and reasonable concepts has often led to significant advances in science, philosophy and mathematics.

In moral philosophy, paradox plays a particularly central role in debates on ethics. For instance, an ethical admonition to "love thy neighbour" is in (not just contrast but) contradiction with an armed neighbour actively trying to kill you: if he or she succeeds, then, you will not be able to love them. But to pre-emptively attack them or restrain them is not usually understood as very loving. This might be termed an ethical dilemma; another example is the conflict between an injuction not to steal and one to care for a family that you cannot afford to feed except with stolen money.

Table of contents
1 Common themes in paradoxes
2 List of paradoxes
3 See also
4 References
5 External links

Common themes in paradoxes

Common themes in paradoxes include direct and indirect self-reference, infinity, circular definitions, and confusion of levels of reasoning.

W. V. Quine [1] distinguished three classes of paradox.

List of paradoxes

Not all paradoxes fit neatly into one category. Some paradoxes include:

Veridical paradoxes

These are unintuitive results of correct logical reasoning.




Falsidical paradoxes

These are incorrect results of subtly false reasoning.


Paradoxes that show flaws in accepted
reasoning, axioms, or definitions. Note that many of these are special cases, or adaptations, of the Russell's paradox.

Antinomies of definition

These paradoxes rest simply on an ambiguous definition.

Conditional paradoxes

These are paradoxes only if certain special assumptions are made. Some of these show that those assumptions are false or incomplete, others are are other types of paradoxes.

Other paradoxes

See also


External links