Peter Singer on Why Persons are Irreplaceable

In the preface to the second edition of his deservedly popular Practical Ethics, Peter Singer notes that one of the ‘two significant changes†of his ‘underlying ethical views†consists in dropping the tentative suggestion that ‘one might try to combine both the “total†and the “prior existence†versions of utilitarianism, applying the former to sentient beings who are not self-conscious and the latter to those who are†(pp. x–xi). On the total view our aim is ‘to increase the total amount of pleasure (and reduce the total amount of pain)†regardless of ‘whether this is done by increasing the pleasure of existing beings, or increasing the number of beings who exist†, whereas on the prior existence view we ‘count only beings who already exist, prior to the decision we are taking, or at least will exist independently of that decision†(p. 103). Instead he proposes ‘that preference utilitarianism draws a sufficiently sharp distinction between these two categories of being to enable us to apply one version of utilitarianism to all sentient beings†(p. xi).