Derek Parfit

(1942 - 2017)

We can start with some science fiction. Here on Earth, I enter the Teletransporter. When I press some button, a machine destroys my body, while recording the exact states of all my cells. The information is sent by radio to Mars, where another machine makes, out of organic materials, a perfect copy of my body. The person who wakes up on Mars seems to remember living my life up to the moment when I pressed the button, and he is in every other way just like me. Of those who have thought about such cases, some believe that it would be I who would wake up on Mars. They regard Teletransportation as merely the fastest way of travelling. Others believe that, if I chose to be Teletransported, I would be making a terrible mistake. On their view, the person who wakes up would be a mere Replica of me.

This article discusses the relation between prioritarian and egalitarian principles, whether and why we need to appeal to both kinds of principle, how prioritarians can answer various objections, especially those put forward by Michael Otsuka and Alex Voorhoeve, the moral difference between cases in which our acts could affect only one person or two or more people, veil of ignorance contractualism and utilitarianism, what prioritarians should claim about cases in which the effects of our acts are uncertain, the relative moral importance of actual and expectable benefits, whether people should sometimes be given various chances of receiving benefits, and principles that appeal to competing claims

When we have a normative reason, and we act for that reason, it becomes our motivating reason. But we can have either kind of reason without having the other. Thus, if I jump into the canal, my motivating reason was provided by my belief; but I had no normative reason to jump. I merely thought I did. And, if I failed to notice that the canal was frozen, I had a reason not to jump that, because it was unknown to me, did not motivate me. Though we can have normative reasons without being motivated, and vice versa, such reasons are closely related to our motivation. There are, however, very different views about what this relation is. This disagreement raises wider questions about what normative reasons are, and about which reasons there are. After sketching some of these views, I shall discuss some arguments by Williams, and then say where, in my opinion, the truth lies. [...] I [will] suggest why, as I believe, we should be non-reductive normative realists, and should regard all reasons as external.

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.