(logic) A paradox arising from vague predicates and repeatedly applying a small difference. For example, removing one grain from a heap of sand still leaves a heap, yet removing enough grains will eventually not leave a heap.

plural of sorites paradox

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

(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.

(set theory) The paradox that supposing the existence of a set of all ordinal numbers leads to a contradiction; construed as meaning that it is not a properly defined set.

plural of paradoxical rage reaction

(medicine) An aggressive behaviour sometimes manifested by patients taking certain drugs, such as benzodiazepines.

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