How to read Derek Parfit's "Reasons & Persons"
Derek Parfit was a genius, and you should read his books. He wrote two: Reasons & Persons (great), and On What Matters (great, but also bad).
Sometimes non-philosophy people get together to read Reasons & Persons in a book group. Typically this is because they are {Rationalists, Effective Altruists} (Parfit is sort of the grandfather of EA), or are {Rat, EA}-adjacent, or because they just generally care about goodness and truth. Such reading groups tend either to collapse immediately, or to limp on miserably. This is almost certainly due to one mistake: reading the book in printed order.
Reasons & Persons has four parts:
- On self-defeating theories
- On rationality and time
- On personal identity
- On population ethics
You should almost certainly read these parts in quasi reverse order -- that is, the order is 4,3,1,2.
Part 4 contains Parfit's work on population ethics, which was revolutionary and still matters. The mere addition paradox, the non-identity problem, impartiality -- all this stuff rocks, is original to Parfit, is really clearly argued, demands few prerequisites, and matters practically for everyone who cares about making choices that increase the well-being of future people. I am also very fond of the ending of the book (which is something of a "banger", but only under the standards of academic philosophy):
There could clearly be higher achievements in the struggle for a wholly just world-wide community. And there could be higher achievements in all of the Arts and Sciences. But the progress could be greatest in what is now the least advanced of these Arts or Sciences. This, I have claimed, is Non-Religious Ethics. Belief in God, or in many gods, prevented the free development of moral reasoning. Disbelief in God, openly admitted by a majority, is a recent event, not yet completed. Because this event is so recent, Non-Religious Ethics is at a very early stage. We cannot yet predict whether, as in Mathematics, we will all reach agreement. Since we cannot know how Ethics will develop, it is not irrational to have high hopes.
It is NOT irrational to have high hopes, bozo, so get to work.
Part 3 (Personal Identity) is incredibly profound. It is, again, very well argued, original to Parfit, and requires few prerequisites. Teletransportation, split-brain, the argument that identity doesn't matter -- FIRE, all of it. I find Parfit's reductionism completely persuasive, and it succeeds as a theory of personal identity where Buddhism fails. I also think that the literature on personal identity has not seen many improvements upon Parfit's work since.
This section also contains these extraordinary words:
The truth is very different from what we are inclined to believe. Even if we are not aware of this, most of us are Non-Reductionists. If we considered my imagined cases, we would be strongly inclined to believe that our continued existence is a deep further fact, distinct from physical and psychological continuity, and a fact that must be all-or-nothing. This is not true. Is the truth depressing? Some may find it so. But I find it liberating, and consoling. When I believed that my existence was such a further fact, I seemed imprisoned in myself. My life seemed like a glass tunnel, through which I was moving faster every year, and at the end of which there was darkness. When I changed my view, the walls of my glass tunnel disappeared. I now live in the open air. There is still a difference between my life and the lives of other people. But the difference is less. Other people are closer. I am less concerned about the rest of my own life, and more concerned about the lives of others.
Peak.
Parts 1 and 2 are about the ways in which moral theories can be self-defeating. This analysis is quite technical, and is not widely adopted. It contains many excellent things, like "Parfit's Hitchhiker," which is a thought experiment that suggests you can have self-interested reasons to be self-denying:
Suppose that I am driving at midnight through some desert. My car breaks down. You are a stranger, and the only other driver near. I manage to stop you, and I offer you a great reward if you rescue me. I cannot reward you now, but I promise to do so when we reach my home. Suppose next that I am transparent, unable to deceive others. I cannot lie convincingly. Either a blush, or my tone of voice, always gives me away. Suppose, finally, that I know myself to be never self-denying. If you drive me to my home, it would be worse for me if I gave you the promised reward. Since I know that I never do what will be worse for me, I know that I shall break my promise. Given my inability to lie convincingly, you know this too. You do not believe my promise, and therefore leave me stranded in the desert. This happens to me because I am never self-denying. It would have been better for me if I had been trustworthy, disposed to keep my promises even when doing so would be worse for me. You would then have rescued me.
Despite the wealth of juicy thought experiments, the limits of Parfit's skills in mathematics and decision theory are felt in these sections. The core insight here (in my opinion, and stated in concepts that are not Parfit's) is just this: optimal moral algorithms are unlikely to be greedy algorithms (i.e. you can't just make a locally optimal choice at each stage and expect to find a global optimum). Many naively self-interested theories of maximizing pleasure can fail if they only consider the margin. Parfit's hitchhiker is an example of this. Parfit's other thought experiments and examples can at times feel confusingly elaborate, because the core idea is so simple. These sections are important bits of Parfit-thought, as they provide grounds to embrace non-partiality (i.e. caring about others). But many better arguments and frames for this notion will be presented later on in On What Matters.
Anyways, now you know how to read Reasons & Persons. Have fun!