Editing Mere addition paradox (section)

==The paradox==

Parfit considers four populations, as depicted in the following diagram: A, A+, B− and B. Each bar represents a distinct group of people. The bars' width represents group size while the bar's height represents group [[happiness]]. Unlike A and B, A+ and B− are complex populations, each comprising two distinct groups of people. It is also stipulated that the lives of the members of each group are good enough that they would rather be alive than not exist.<ref name=":1">{{Cite web |last=Matthews |first=Dylan |date=2017-01-03 |title=The whole philosophy community is mourning Derek Parfit. Here’s why he mattered. |url=https://www.vox.com/science-and-health/2017/1/3/14148208/derek-parfit-rip-obit |access-date=2025-01-26 |website=Vox |language=en-US}}</ref><ref name=":0">{{Cite book |last=Parfit |first=Derek |url=https://archive.org/details/reasonspersons00parf |title=Reasons and Persons |publisher=Oxford University Press |year=1984 |isbn=978-0198249085 |location=New York |url-access=registration}}</ref>

[[File:MereAddition.svg|center]]

Parfit makes the following three suggestions regarding the value of the populations: 

::'''1.''' A+ seems no worse than A. This is because the people in A are no worse-off in A+, while the additional people who exist in A+ are better off in A+ compared to A, since it is stipulated that their lives are good enough that it is better for them to be alive than to not exist.

::'''2.''' B− seems better than A+. This is because B− has greater total and average happiness than A+.

::'''3.''' B seems equally as good as B−, as the only difference between B− and B is that the two groups in B− are merged to form one group in B.

Together, these three comparisons entail that B is better than A. However, Parfit also observes the following: 

::'''4.''' When we directly compare A (a population with high average happiness) and B (a population with lower average happiness, but more total happiness because of its larger population), it may seem that B can be worse than A.

Thus, there is a paradox. The following intuitively plausible claims are jointly incompatible: (1) that A+ is no worse than A, (2) that B− is better than A+, (3) that B− is as good as B, and (4) that B can be worse than A.

=== The repugnant conclusion ===
[[File:RepugnantConclusion.svg|center|frameless|upright=1.4]]
Parfit argues that this mere addition from A to B can be repeated over and over, eventually resulting in a much larger population Z with only slightly positive welfare. The assessment that such a population Z would be better is what Parfit calls the repugnant conclusion.<ref name=":1" /><ref name=":0" />