Mere addition paradox

The mere addition paradox (also known as the repugnant conclusion) is a problem in ethics identified by Derek Parfit and discussed in his book Reasons and Persons (1984).

The paradox identifies the mutual incompatibility of four intuitively compelling assertions about the relative value of populations.

[2][3] Some scholars, such as Larry Temkin and Stuart Rachels, argue that inconsistencies between the four claims (above) rely on the assumption that the "better than" relation is transitive.

[8] A number of philosophers (including Torbjörn Tännsjö, Yew-Kwang Ng, Hilary Greaves and Toby Ord) have agreed that avoiding the repugnant conclusion is not a necessary criterion for a satisfactory theory of population ethics.

It states that according to some ethical theories, for any population where everyone has very high well-being, there exists a better population consisting of two groups: a significant number of people with very negative well-being, and a much larger number of people having barely positive welfare.