Source: Benatar, David. Better Never to Have Been (2008 1 edn). pp. 171-172.
Although the impersonal average view also solves the nonidentity problem, it too cannot be Theory X, for it faces other problems. To show why this is the case, Derek Parfit asks us to imagine another two worlds. In the first world everybody had a very high quality of life. In the second world, in addition to all these people with their same high quality of life there are additional people who, although not quite as well off, nonetheless have lives that are well worth living. These sorts of cases, Derek Parfit calls ‘Mere Addition’. More specifically, mere addition occurs ‘when, in one of two outcomes, there exist extra people (1) who have lives worth living, (2) who affect no one else, and (3) whose existence does not involve social injustice’.²²
Now the impersonal average view says that the second world is worse, because [4.] the average quality of life is lower. It is made lower by the mere addition of extra people who, although happy, are not quite as happy as the original people are. Derek Parfit takes this to be implausible. It would entail, he says, that [5.] it would be worse if in addition to Adam and Eve leading blissful lives, there were a billion extra people who lived lives of slightly lower quality. The impersonal average view also entails, he says, that whether it is wrong to have any given child depends on facts about the quality of all previous lives. Thus, if [6.]‘the ancient Egyptians had a very high quality of life, it is more likely to be bad to have a child now’.²³ But, says Professor Parfit, ‘research in Egyptology cannot be relevant to our decision whether to have children.’²⁴ Accordingly, he takes the impersonal average view to be implausible.
²² Parfit, Derek, Reasons and Persons, 420. ²³ Ibid. ²⁴ Ibid.
I acknowledge that most parents nowadays don't mull reproduction that thoroughly, but Parfit's outlook feels wrong to me. How can't a reasonable person:
mull (4)-(6) overhead as factors in a decision to reproduce?
be dissuaded and thwarted from procreation by (4)-(6)?