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.

I did not, as James Sterba writes, claim to have explained "the asymmetry view." I claimed that, since my suggested explanation makes it impossible to solve the Paradox of Future Individuals, "we must abandon" one of its essential premises (my p. i52). Sterba's main claim is that my suggested explanation "does not so much explain or justify the [asymmetry] view as simply restate it." Is this so? My explanation assumed (W) that an act cannot be wrong if it will not be bad for any of the people who ever live.' Sterba asks why we should not appeal instead to one of my Wide Principles, which are concerned with possible effects on people who might have lived. And he suggests that, since "the only ground" for preferring (W) is that it explains the asymmetry view, (W) cannot explain this view. There are other grounds for appealing to (W), such as those provided by certain theories about the nature of moral reasoning. On Scanlon's theory, for example, our fundamental moral motive is "to be able to justify one's actions to others on grounds that they could not reasonably reject.'" We may claim that, on such a theory, an act cannot be wrong unless it will affect someone in a way that cannot be justified unless there will be some complainant whose complaint cannot be answered. Similarly, Brandt suggests that, by the phrase "is morally wrong," we should mean "would be prohibited by any moral code which all fully rational persons would tend to support... for the society of the agent, if they expected to spend a lifetime in that society."> It seems likely that, on the chosen..