Reasons and Persons

"Brilliant and written as though by an alien intelligence — on the nature of personal identity and morality."

"Reasons and Persons was written in 1984, and Derek Parfit was one of my postgraduate supervisors. One of the blurbs on the back of book says “ Reasons and Persons is a work of genius”, and I think it is. It’s an incredibly important book, and one written in a tradition completely different to Bernard Williams , even though the two were friends. Bernard Williams is an essayist and he looks at the big picture, like Nagel. Parfit, more like Singer, is in the tradition of the 19th century philosopher Henry Sidgwick – he is a detailed, rigorous, almost mathematical philosopher, who worked from premises slowly to conclusions. There’s nothing pretentious about it – it’s beautifully written, incredibly thoughtful and well-argued, with fantastically imaginative thought experiments. I’m particularly interested in the final chapter, about our obligations to future generations. There are various paradoxes that he tries to resolve. Here’s one of them. Suppose you knew that if you were to have a child, the child would have a terribly wretched life – it would be miserable, suffer for some years and then die. Would it be a bad thing to bring that life into the world, if it was going to be unremittingly miserable? Most people would agree that it would be. So does that then mean that it’s a good thing to bring a life that is better than nothing into the world? If you say it is, you get involved in what he calls the “repugnant conclusion”. Imagine a world with a trillion people in it, all of whose lives are only slightly better than nothing – they have enough to eat and drink, but there is nothing really fulfilling about their existence. They aren’t leading the sort of flourishing life that you have, doing Five Books interviews. Compare that with a world in which there are only a few billion people, all of whom have a very high standard of living. Most people would say that the latter is better than the former. But if you think there is something worthwhile about every life where there is more happiness than there is suffering, then you reach the repugnant conclusion, which is that the world with a trillion people is better, because of the cumulative happiness of that greater population."

"Derek Parfit is much less known in the public sphere than Peter Singer. He never wrote books intended for a general audience, but within academia, he was significantly more influential. His book Reasons and Persons , especially, has over 10,000 citations. I would say that Derek Parfit was the most brilliant philosopher of the 20th century. Others would maybe dispute that claim, but everyone would agree that he would be in the top 5. Reasons and Persons is so important because it introduced to the world the field of population ethics: reasoning ethically about the value of increasing the size of the population in the world, and the size of the population in the future. Is it better to have more people if those people have happy lives? Is it worse to have more people if those people have a life so bad it’s not worth living? If it is better to have more people, what is exactly the theory that governs how to think about these changes in the size of the population? Do you just add up the happiness of everyone? If so, you get counterintuitive conclusions. Do you just try to maximize the average well-being? If so, you also get counterintuitive conclusions. Parfit raised those questions, without claiming to have an answer. He made many fundamental breakthroughs in his book as well, and I think that this field of inquiry is among the most important ones right now. The conclusions we ought to draw given the many decades of research done since Parfit’s book, mean that we should think that, all else equal, it’s good to have one more person if they’re sufficiently well-off. That’s a huge departure from common sense ethics, and it’s extremely important from a moral standpoint. I do agree that it’s a pressing matter, and even possibly the most important set of issues we face. We are remarkably early in the story of civilization. Almost all the value that the human race could achieve lies in the future: all the greatest scientific advances, works of art, peaks of happiness and creativity. But we now seem to be entering a stage where there is at least some chance that all those things could be lost. The biggest shift occurred in 1945 with the use of nuclear weapons, which put on the table the idea that we could develop technology so powerful that we’d be capable of destroying ourselves. The study of existential risks receives very little attention, in the order of a few tens of millions of dollars per year; but it’s increasing. “Almost all the value that the human race could achieve lies in the future: all the greatest scientific advances, works of art, peaks of happiness and creativity.” The reason for this renewed attention is twofold. First, the success of the effective altruism movement means that more people are taking these issues seriously, and are trying to think about how to deal with them—and key researchers like Nick Bostrom are doing very good work on this. Second, these issues have become more salient now. Worry about existential risks was very widespread in the 1960s and 1970s, with strong protests against nuclear weapons. Of course it wasn’t referred to as an existential risk, but simply as nuclear proliferation. Nowadays we have identified many of those risks: war, nuclear weapons, climate change, man-made pandemic, artificial intelligence, etc. And just as with the effective altruism movement, having something concrete rather than abstract to worry about is much more compelling. I think I’ll disagree with Derek Parfit on this one! I think there are a couple of considerations that he maybe doesn’t mention, but which are very important in setting that threshold. Giving more has two effects: obviously it means more money is going to charity, but it slightly decreases your own living conditions. Perhaps it has zero effect to begin with, but as you start to donate more and more, now you might have to take slower transport to get to the office, or buy a cheaper suit which could impact your job prospects, etc. At some point those considerations outweigh the benefits of your donations. For someone in a rich country, the point at which it’s no longer optimal to keep donating is much higher than a poverty threshold of two dollars per day—because if you gave everything above two dollars a day, you simply wouldn’t be able to live in a rich country, and therefore earn money to donate. A second point is that we should be actualists. Actualism versus possibilism is a question in moral philosophy, which can be framed like this: when I decide what I ought to do today, should I take into account my own future weakness of the will? Actualism says that we should. If you give away all of your savings at once today—which you could technically do—you’ll probably get so frustrated that you’ll simply stop giving in the future. Whereas if you decide to give 10% of your earnings, this commitment will be sustainable enough that you’ll continue doing it over many years in the future, resulting in a higher overall amount, and thus a higher impact. Therefore, an actualist says that you should give only 10%. In my opinion, the best philosophical answer to the question of how much you ought to give, is that you should give as much as you can to maximize your long-term giving, taking into account both the fact that you can spend money to make more money, and this concept of future weakness of the will. And then of course, there is the question of how demanding this commitment is—but I think that for most people it isn’t very demanding at all. If you live in a rich country and pledge to give 10% of your earnings, you’re still living a better life than almost everyone who’s ever lived."

"Brilliant and written as though by an alien intelligence. A deeply strange book filled with thought experiments that bend your intuitions left and right. A truly strange and unique document, and incredibly insightful about morality and questions of identity."