Derek Parfit

(1942 - 2017)

Presents actual cases of brain bisection; how we might be able to divide and reunite our minds; what explains the unity of consciousness at any time; the imagined case of full division, in which each half of our brain would be successfully transplanted into the empty skull of another body; why neither of the resulting people would be us; why this would not matter, since our relation to each of these people contains what matters in the prudential sense, giving us reasons to care about these people, which are like our reasons to care about our own future;and how it is hard to believe that personal identity, or our own continued existence, is not what matters.

One theory about rationality is the Self-interest Theory, or S. S claims that what each of us has most reason to do is whatever would be best for himself. And it is irrational for anyone to do what he knows would be worse for himself. When morality conflicts with self-interest, many people would reject the Self-interest Theory. But most of these people would accept one of the claims that S makes. This is the claim that we should not care less about our further future, simply because it is further in the future. We should not, for example, postpone pains at the foreseen cost of making them much worse. In our concern for our own self-interest, we should give equal weight to all the parts of our future. In this paper I shall discuss how a Self-interest Theorist should defend this claim.

sonable, in this sense, if we ignore, or give too little weight to, some other people's well-being or moral claims.' Some critics have suggested that, because Scanlon appeals to this sense of 'reasonable', his formula is empty. On this objection, whenever we believe that some act is wrong, we shall believe that people have moral claims not to be treated in this way. We could therefore argue that such acts are disallowed by some principle which no one could reasonably reject, since anyone who rejected this principle would be giving too little weight to people's moral claims not to be treated in this way. Since everyone could claim that the principles which they accept could not be reasonably rejected, Scanlon's Formula would make no difference to our moral thinking. That is not so. If we reject the principles that disallow certain acts, we are denying that such acts are wrong. This denial would be unreasonable if it would give too little weight to some other people's moral claims. So Scanlon's Formula implies that..