The situation where a group of people collectively decide on a course of action that goes against the preferences of many or all of the individuals in the group, because the individuals choose to side with what they believe is the majority preference.

A choice problem designed to show an inconsistency of actual observed choices with the predictions of expected utility theory.

A contradiction between two basic meaning traits (semes) within a story.

(rhetoric) A contradiction in related terms or ideas. Usually an inconsistency in syllogisms, of a person or group supposedly of one set of ideals.

(by extension) Any contradiction or paradox.

(rhetoric) Proving indirectly, by showing the impossibility or absurdity of the contrary.

Being a style of argument in which a person presents their reasoning as categorically true, even if it is not necessarily so.

(philosophy) A form of dialectical argument that affirms two opposing ideas and thus seems to prove a contradiction.

(philosophy, post-structuralism) An insoluble contradiction in a text's meaning; a logical impasse suggested by a text or speaker.

The phenomenon of an arrow travelling in the direction where it points when the bow is fully drawn, when it seems that the arrow would have to pass through its original position. The explanation relates to the bending of the arrow when released.

A paradox of self-reference, where, supposing that every man either shaves himself or is shaved by the barber, and the barber shaves all and only the men who do not shave themselves, then it is impossible to determine who shaves the barber.

(philosophy) A philosophical problem whereby a man intends to walk a mile from a particular point, but an infinity of gods separately plan to obstruct him. One of them will raise a barrier to stop his further advance if he reaches the half-mile point, a second if he reaches the quarter-mile point, a third if he goes one-eighth of a mile, and so on ad infinitum. The paradox involves the fact that (i) the man cannot begin walking, because a barrier will stop him even at the shortest distance, but (ii) if he does not begin walking, no barrier will rise.

A particular self-referential paradox relating to the number of words in a descriptive phrase.

(probability) A problem within the classical interpretation of probability theory, illustrating how the principle of indifference may not produce definite, well-defined results for probabilities if it is applied uncritically when the domain of possibilities is infinite.

The linguistic paradox that, if there are unnameable things, their existence cannot be indicated without naming them in some way.

A time travel paradox in which the consequences of an event in the future travel back in time and cause an event in the past or present, which in turn is among the causes of the first event, forming a causal loop in which each event is caused by the other.

An apparent paradox in probability theory, illustrated by various questions about the probability of a child within a family being of a particular sex.

(philosophy) A self-referential paradox involving a proposition pronounced about an event that might or might not happen in the future. Socrates wishes to cross a bridge guarded by Plato, who says that if the next proposition Socrates utters is true, Socrates will be permitted to cross, but otherwise he will be thrown into the water. Socrates replies, "You will throw me into the water." Plato is then in a paradoxical situation regarding how to treat Socrates.

Alternative spelling of chicken-or-egg question [(logic, philosophy) A supposed paradox concerning whether chickens or chicken eggs existed first.]

Alternative form of chicken-or-egg question [(logic, philosophy) A supposed paradox concerning whether chickens or chicken eggs existed first.]

Alternative spelling of chicken-or-egg question [(logic, philosophy) A supposed paradox concerning whether chickens or chicken eggs existed first.]

(logic, philosophy) A supposed paradox concerning whether chickens or chicken eggs existed first.

(of an argument, sometimes hyphenated) Characterized by equivocation or by overly complex or specious argumentation; improperly reasoned.

Alternative spelling of chop logic [(of an argument, sometimes hyphenated) Characterized by equivocation or by overly complex or specious argumentation; improperly reasoned.]

(countable) A logical inconsistency among two or more elements or propositions.

(logic, philosophy) A worldview according to which contradictory statements can both be true.

Pertaining to or being a contranym.

(philosophy, logic) A counterfactual in which the antecedent could not possibly be true.

(logic, archaic) A sophistical mode of arguing.

A contradiction of ideas that serves as the determining factor in their interaction.

A statement that is both true and false; a true contradiction.

(logic) The theory that statements can be both true and false at the same time and in the same sense. The opposite of the law of noncontradiction.

(epistemology) The argument that any proposition requires a justification, but the justification itself requires support, which leads to infinite regress.

The apparent contradiction that, although water is generally more useful than diamonds, diamonds command a higher price in the market.

The holding of two contradictory beliefs in one's mind simultaneously and accepting both of them as true or correct, without realizing the contradiction.

(economics) The apparently paradoxical observation that people's reported happiness varies directly with income both among and within nations, but over time happiness does not trend upward as income continues to grow.

A paradox of choice in which people's decisions produce inconsistencies with subjective expected utility theory.

A form of self-referential logical paradox associated with statements of the form "All Cretans are liars" (spoken by Epimenedes, himself a Cretan, who must therefore be lying).

(logic) A logical fallacy resulting from the use of multiple meanings of a single expression.

(rhetoric) A situation in which two alternative points of view are presented as the only options, when others are available.

A situation in which two opposing options are presented as the only possibilities, when others are available.

Alternative letter-case form of Fermi paradox [(biology, exobiology) The seeming contradiction, serving as a challenge to believers in the existence of advanced lifeforms throughout the universe, that there is no scientific evidence that extraterrestrial civilizations have tried to visit or communicate with Earth.]

A paradox of deontic logic, whereby the plausible statements (i) if you murder, you ought to murder gently, (ii) you do commit murder, and (iii) to murder gently you must murder imply the less plausible statement (iv) you ought to murder.

(economics) The observation that the rate of interest and the general level of prices are positively correlated.

A particular paradox in mathematical logic; the type-theoretic analogue of Russell's paradox from set theory.

The paradox of time travel in which inconsistencies emerge through changing the past.

A philosophical problem related to Benardete's paradox, but involving countably many Grim Reapers, each of which will kill the person in question at a certain time (if still alive), taking a certain period of time to do it.

Synonym of unexpected hanging paradox

A paradox arising from the question of what constitutes evidence for a statement. Observing objects that are neither black nor ravens may formally increase the likelihood that all ravens are black, even though, intuitively, these observations are unrelated.

Alternative form of ipse dixit [(rhetoric) A dogmatic and unproved proposition or dictum that is accepted solely on the authority of someone who is known to have asserted it.]

(countable) An ironic statement.

A riddle with no solution, used to provoke reflection on the inadequacy of logical reasoning, and to lead to enlightenment.

(philosophy, logic) A paradox involving statements such as "this sentence is false", or "the following statement is true: the previous statement is false", which cannot be meaningfully regarded as either true or false.

The objection that it should not be possible to deduce an irreversible process from time-symmetric dynamics.

Synonym of Curry's paradox

The paradox whereby aid agencies report the success of most of their programs, yet it is impossible to establish any significant correlation between aid and GDP growth in developing countries.

A false dilemma in which contradictory arguments lead to the same (unpleasant) conclusion.

The fallacious belief that something is automatically good because it is natural or automatically bad because it is unnatural.

An apparent paradox within the subjectivistic interpretation of probability theory, in which two people wager over whose necktie is cheapest, with the owner of the more expensive tie giving it to the other. Taking the wager seems to be to the advantage of both people.

Synonym of Newcomb's paradox

The informal fallacy of comparing actual things with unrealistic, idealized alternatives.

(physics) A conjecture asserting that it is impossible to create paradoxes by time travel because the past cannot be changed.

The situation in which a phenomenon being observed for study is unwittingly influenced by the presence of the observer.

An apparently self-contradictory statement, which can only be true if it is false, and vice versa.

(economics) A paradox of economics, stating that an increase in autonomous saving leads to a decrease in aggregate demand and thus a decrease in gross output which will in turn lower total saving: narrowly speaking, total saving may fall because of individuals' attempts to increase their saving, and, broadly speaking, increase in saving may be harmful to an economy.

(obsolete) paradoxical

Person who comes up with a paradox.

Alternative form of paradoxical [Having self-contradictory properties.]

A person who formulates or uses paradoxes.

An avant-garde movement in the arts etc, based on heavy use of contradictions and paradoxes, founded by F. Smarandache in the 1980s.

A small paradox.

(obsolete) The use of paradoxes.

(countable) A paradoxical statement; a paradox.

(logic) Relating to paralogy; fallacious

(logic) paralogism, fallacy

(game theory) The paradox whereby a combination of losing strategies (such as alternating between two games that each, played individually, would result in an overall loss) may give a winning strategy.

A striking or paradoxical assertion; an obscure saying; an enigma; a parable.

Alternative form of pseudoargument [fallacious argument, incorrect argument]

In the neo-Gricean semantics and pragmatics of Laurence R. Horn: a reformulation of Paul Grice's maxim of quantity combined with the first two submaxims of manner, stating: "Say as much as you can (given R)", and leading to the implicature that if the speaker did not make a stronger statement (or say more), then its denial is (implied to be) true.

Hempel's paradox

A hypothetical problem dealing with the notion of infinity. Given an empty vase and an infinite supply of balls, an infinite number of steps are performed, such that at each step 10 balls are added to the vase and one ball removed from it. The question is then posed: how many balls are in the vase when the task is finished?

(philosophy, of a statement or idea) That is inherently disproven, undermined or hindered by the very act of expressing it, but without it being a logical contradiction.

The observation that the association of two variables for one subset of a population may be similar to the association of those variables in another subset, but different from the association of the variables in the total population.

A singular statement that states the existence of its subject.

(economics) The paradox raised by a particular (theoretical) lottery game that leads to a random variable with infinite expected value (i.e. infinite expected payoff) but nevertheless seems to be worth only a very small amount to the participants.

(rhetoric) Omission of the conclusion of a syllogistic argument.

A tautological statement; tautology.

(logic) A form of selection bias in which a type of thing is judged to be of poor quality in general, caused by the fact that only poor quality instances of that thing are generally noticed.

(relativity) The clock paradox.

A paradox about a person's expectations about the timing of a future event which they are told will occur at an unexpected time. It is based on the idea that a prisoner, told that he will be hanged on a day unknown to him, concludes that "I cannot be hanged on Friday because if I haven't been hanged by the end of Thursday then it would no longer be a surprise", and so on backwards through the week.

A logical paradox resembling the liar paradox but using, instead of a single sentence, an infinite sequence of statements, each referring to the truth values of the later statements in the sequence, and thus attempting to avoid circularity.

(linguistics) Present at an abstract level, but not realized in the surface form.

Obsolete form of equivocation. [(logic) A logical fallacy resulting from the use of multiple meanings of a single expression.]