Page "Mere addition paradox" Paragraph 7

The difference between the situations A and A + is only in the existence of extra people at a lower level of happiness.

If the two populations were known to each other, and were aware of the inequality, this would arguably constitute social injustice.

However, as they do not, Parfit says this represents a Mere Addition, and it seems implausible to him that it would be worse for the extra people to exist.

Thus, he argues, A + is not worse than A.