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.

(physics) A physical paradox that arises when considering the buoyant force exerted on a relativistic bullet (or in a submarine) immersed in a fluid subject to an ambient gravitational field. If a bullet has neutral buoyancy at rest in a perfect fluid and is then launched at relativistic speed, observers at rest within the fluid would conclude that the bullet should sink, since its density will increase due to the length contraction effect. On the other hand, in the bullet's proper frame it is the moving fluid that becomes denser and hence the bullet would float.

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

(physics) Synonym of Supplee's paradox

(genetics) The observation that the C-value of an organism is not dependent on its complexity (presumed number of genes)

(mathematics) A theorem in set-theoretic geometry, which states that given a solid ball in three‑dimensional space, there exists a decomposition of the ball into a finite number of disjoint subsets, which can then be put back together in a different way to yield two identical copies of the original ball.

A semantic paradox of self-reference, where, supposing that "autological" means "self-describing" and "heterological" means "not self-describing", then "heterological" itself cannot be meaningfully classified as either of the two.

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.

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

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.