Should paternity testing be compulsory at birth? In discussions of this elsewhere I haven’t seen one set of interests come up: those of children who would not be born if their mothers were faithful. At the start of mandatory paternity testing there would be a round of marriages breaking up at the hospital, but soon unfaithful women would learn to be more careful, and there just wouldn’t be so many children. This is pretty bad for the children who aren’t. Is a life worth more than not being cuckolded? Consider, if you could sit up on a cloud and choose whether to be born or not, knowing that at some point in your life you would be cuckolded if you lived, would you? If so, it looks like you shouldn’t support mandatory paternity testing at the moment. This is of course an annoying side effect of an otherwise fine policy. If incentives for childbearing were suitably high it would not be important, but at the moment the marginal benefit of having a child appears reasonably high, so the population effects of other policies such as this probably overwhelm the benefits of their intentional features.

You may argue that the externalities from people being alive are so great that additional people are a bad thing – if they are a very bad thing then the population effect may still dominate, but mean that the policy is a good idea regardless of the effect on married couples. I haven’t seen a persuasive case for the externalities of a person strongly negative enough to make up for the greatness of being alive, but feel free to point me to any.