Derek Parfit

(1942 - 2017)

Explains why C cannot be directly self‐defeating. Theories are agent‐relative if they give different agents different aims. Two such theories are S and Common Sense Morality, or M. It is often true that, if each of several people does what would be best for themselves, that would be worse for all these people. In such cases, S is directly collectively self‐defeating. In moral analogues of such cases, M is similarly self‐defeating. The chapter describes how these problems can have political, psychological, or moral solutions.

This chapter discusses problems for informational patternism and the popular soul theory of personal identity, suggests that they are incoherent, and urges that the self does not really exist. It employs the science fiction pseudotechnology of a teleporter and presents the example of split brains from actual neuroscience cases. There are two theories about what persons are, and what is involved in a person's continued existence over time. On the Ego Theory, a person's continued existence cannot be explained except as the continued existence of a particular Ego, or subject of experiences. According to the Bundle Theory we must claim that there are long series of different mental states and events, each series being what we call one life. The split‐brain cases provide one argument for one view about the nature of persons. In the other, a person's brain is divided, and the halves are transplanted in two different bodies.

Suppose we discover how we could live for a thousand years, but in a way that made us unable to have children. Everyone chooses to live these long lives. After we all die, human history ends, since there would be no future people. Would that be bad? Would we have acted wrongly? Some pessimists would answer No. These people are saddened by the suffering in most people’s lives, and they believe it would be wrong to inflict such suffering on others by having children. In earlier centuries, this bleak view was fairly plausible. But our successors would be able to prevent most human suffering. Some optimists would also answer No . . . These [views] are, I believe, deeply mistaken. Given what our successors could achieve in the next million or billion years, here and elsewhere in our galaxy, it would be likely to be very much worse if there were no future people.

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..