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Reasons and Persons

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Challenging, with several powerful arguments, some of our deepest beliefs about rationality, morality, and personal identity, Derek Parfit claims that we have a false view about our own nature. It is often rational to act against our own best interests, he argues, and most of us have moral views that are self-defeating. We often act wrongly, although we know there will be no one with serious grounds for complaint, and when we consider future generations it is very hard to avoid conclusions that most of us will find very disturbing.

543 pages, Paperback

First published January 1, 1984

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Derek Parfit

20 books256 followers
Derek Parfit was a British Professor of Philosophy at Oxford University specializing in personal identity, rationality, ethics, and the relations between them.

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Displaying 1 - 30 of 119 reviews
Profile Image for kaelan.
259 reviews303 followers
November 17, 2017
Reasons and Persons is unquestionably one of the most important philosophical works of the 20th century, although its conspicuous absence from bookstore shelves might suggest otherwise. But for those planning to read Parfit's masterwork of moral philosophy, I would like to offer two words of warning...

First, Parfit is a very, very rigorous thinker.

While the book doesn't require a whole lot of background knowledge, many readers—including those well versed in philosophy—will probably find it quite difficult. Despite the lucidity of his prose, the Oxford philosopher piles argument upon argument, justifying even the most minor of propositions and invoking lemmas established several chapters earlier. I mean, one only has to look at Paul Ricœur's horribly misinformed objections to see how even a fellow philosopher can get tangled up in Parfit's argumentative webs.

Second, Reasons and Persons is a very, very serious book.

For those coming from an Analytic background, it may come as a shock that we can talk about such things as the value of existence and the nature of personal identity with anything approaching clarity and rigor. Meanwhile, some Continental sympathizers might be skeptical that logical (and often reductionistic) analysis can disclose anything of personal value. Both, however, would be sorely mistaken.

Why? Because with Reasons and Persons, Parfit has created a work that rivals anything in the field of existentialist, anthropocentric philosophy, from Nicomachean Ethics to Being and Time . Yet it's also a testament to argumentative reasoning at its finest. Accordingly, and as strange as it may sound, this book could appeal just as much to the Sartre-lover as to the Kripke-o-phile. All you need is determination (essential), a strong rational faculty (useful) and an inquisitive mind (absolutely required).

At this junction, I'd hate to bog you down with any detailed summary. Still, I should spend at least a few words on what the book is actually about. Parfit divides Reasons and Persons into four loosely related parts, which run as follows:

1. Self-Defeating Theories.

In this somewhat technical section, Parfit explores what it means for a (normative) theory to be self-defeating. Along the way, he makes some interesting remarks about moral dispositions, discusses the infamous prisoner's dilemma and provides an overview of self-interest theory, a theory of rationality that he will spend the remainder of the book arguing against. The academic philosopher would find "Self-Defeating Theories" quite fascinating. The casual reader, not so much.

2. Rationality and Time.

Here, Parfit mounts a two-pronged attack against self-interest theory, invoking both morality and a rival theory of rationality called present-aim theory. Self-interest theory claims that we should only care about ourselves. Present-aim theory, by contrast, claims that we should only care about ourselves now. According to Parfit, defences of self-interest theory often invoke arguments that apply to either morality or present-aim theory. Only by assaulting it on both fronts can we discover its true worth.

3. Personality Identity.

In what's probably the most famous part of Reasons and Persons, Parfit defends a reductionist account of personal identity. As he sees it, personal identity is nothing more than psychic continuity plus (maybe) physical continuity. The important point: it doesn't involve some deep further fact. As a result, the question of "Will I be dead at time t?" may not always merit a simple "yes" or "no" response. In some special cases, the answer will be indeterminate.

Of all of Parfit's many claims, this one probably runs the most counter to our usual beliefs and intuitions. Thus, it's the one that people tend to latch on to when they read this book. But in any case, "Personality Identity" contains some legitimately mind-bending ideas, and it allows Parfit to run wild with his sci-fi thought experiments. All in all, the most accessible part of Reasons and Persons. Casual readers: read this part first.

4. Future Generations.

Drawing on results in contemporary metaphysics and the philosophy of language, Parft argues that some morally relevant actions cause people to exist; and in some cases, these people will suffer because of that action. But here lies the issue: if the action wasn't carried out, these people wouldn't exist at all. How, then, can we condemn an action if it brings into existence the very people that it harms?

(Take teen pregnancy, for instance. If a girl has a baby when she's only sixteen-years-old, you might suppose that she ought to have waited until she was older. Moreover, you might say that she ought to have waited for the baby's sake. Now, this last point isn't exactly right. Because if she had waited, say, ten years to give birth, she wouldn't have given birth to this child. That is to say, if she had waited, that first child would not have existed.)

Of the four parts, I found this last one to be the most difficult. I also found it to be the part that suffered most from Parfit's blatant disregard of meta-ethics. All throughout "Future Generations," he compares the moral "goodness" or "badness" of various (causally independent) outcomes. Would it be better that... or...? Yet for an error theorist or even a constructivist about moral facts, such questions would have no objective answer. Like the question of "Will I be alive at time t?," they would be inherently indeterminate.
Profile Image for Joshua Stein.
210 reviews148 followers
December 27, 2011
Derek Parfit's Reasons and Persons is considered a must read in contemporary ethics. The problem is that it is basically only accessible for those who are already experienced with ethics, and particularly the dense work of many of his predecessors, particularly Henry Sidgwick, to whom Parfit is often compared on the dust jacket. It also requires some familiarity with many of the ethicists that Parfit discusses in the text, particularly Thomas Nagel, John Rawls and G.E. Moore, as well as the classics of ethics (i.e. Kant, Plato, Aristotle, Hume, etc.) and the basic theories.

If you have some experience with those theories of ethics, then the book is absolutely worth the read. It offers the basis of contemporary utilitarian theory better than any other text I've come across, and punches a sharp hole in the egoist arguments that many ethicists run across. Though it is incredibly dense, and Parfit's heavy use of thought experiments can make the text hard to follow, (I definitely recommend a strong cup of coffee before delving in; you'll need to have your full attention on the book) that just makes the text more rewarding, and it is not dense without reason. Parfit has a lot of ground to cover.

At the risk of spoiling the ending, it is important to note that (like many great philosophers) Parfit does not resolve the problems that he presents throughout his book. He unravels many historical and contemporary arguments only to leave the ends hanging, which I suppose is alright, given that he spent nearly 500 pages doing it. His optimism about the possibility of solving those problems does need some explanation, but he does a great job articulating a set of problems for those engaged in ethics to play with. I strongly recommend the book to those who think they might be interested in such problems.
29 reviews10 followers
October 28, 2007
My deep love of this book is counterintuitive; I generally prefer a very different intellectual style to my reflections on the nature of personal identity. Also, I generally tend to get annoyed with excessive use of wildly implausible hypotheticals, which this book uses in droves. Nevertheless, this remains on the most influential philosophical works I've ever read. To what extent are you "the same person" you were 10 years ago? What is your connection to that person? Parfit dramatically and powerfully shows that most of our conventional answers to why we and that person are "the same person" are woefully deficient. I'm not entirely prepared to embrace his reductive theory of personal identity in all respects, but I'm deeply persuaded that whatever theory of personal identity we come to adopt, we'd do well to think much harder about the ways in which that identity over time can be said to be stable. This leads to a fascinating discussion of future oriented ethics as well; it provides a some fresh and fertile ground for thinking about our obligations and relationship to future generations. Sadly, this book is quite technical at times (although not at others), and while it might be possible for a smart reader not trained in philosophy will find it very, very difficult.
1 review2 followers
June 8, 2021
I would like to offer a somewhat iconoclastic reading of Reasons and Persons:

I think Part I of Reasons and Persons is underrated, and contains many of the most useful ideas. E.g., it's basically the best reading I know of if you want to get a deep and principled understanding for why 'naive consequentialism' is a bad idea, but why at the same time worries about naive applications of consequentialism or the demandingness objection and many other popular objections to consequentialism don't succeed at undermining it as ultimate criterion of rightness.

(I also expect that it is the part that would most likely be perceived as pointless hair-splitting.)

And I think the most important thought experiment in Reasons and Persons is not the teleporter, nor Depletion or Two Medical Programs, nor the Repugnant Conclusion or the Absurd Conclusion or the Very Repugnant Conclusion or the Sadistic Conclusion and whatever they're all called - I think it's Writer Kate, and then Parfit's Hitchhiker.

Part II in turn is highly relevant for answering important questions such how to allocate credit between different contributors to charitable projects - donors, grant evaluators, grantees, etc. (and thus how to best set financial incentives for such projects).

Part III is probably more original and groundbreaking than the previous parts. But it is also often misunderstood. I think that Parfit's "relation R" of psychological connectedness/continuity does a lot of the work we might think a more robust notion of personal identity would do - and in fact, Parfit's view helps rationalize some everyday intuitions, e.g., that it's somewhere between unreasonable and impossible to make promises that bind me forever. More broadly, I think that Parfit's view on personal identity is mostly not that revisionary, and that it mostly dispels a theoretical fiction most of our everyday intuitions neither need nor substantively rely on. (There are others, including other philosophers, who disagree with this - and think that there being no fact of the matter about questions of personal identity has, e.g., radically revisionary implications for ethics. But this is not Parfit's view.)

Part IV on population ethics is all good and well. (And in fact, I'm often disappointed by how little most later work in population ethics does to improve on Reasons and Persons.) But its key lessons are already widely appreciated, and today there are more efficient introductions one can get to the field.

All of this is half-serious since I don't think there's a clear and reader-independent fact of the matter of which things in Reasons and Persons are "most important". It's also possible, especially for Part I, that what I think I got out of Reasons and Persons is quite idiosyncratic, and doesn't bear a super direct or obvious relationship to its actual content. Last but not least, it's been 5 years or so since I read Reasons and Persons, so probably some claims in this comment about content in Reasons and Persons are simply false because I misremember what's actually in there.
Profile Image for Daniel Hageman.
323 reviews40 followers
August 3, 2020
It's genuinely difficult to put into words how paradigm-shifting this book is in the fields of moral philosophy and rationality, and likewise now with respect to the confidence I can espouse in regards to a few of my own beliefs, particularly surrounding rationality and the proper way of understanding personal identity. This was the perfect nonfiction book to read with a small group of like-minded people, to really break down the arguments that, while not difficult to understand, maintain a level of depth that warrants a long and arduous journey through the intellectual landscape that is covered. Because I was able to read this as part of such a book club, I have less of a reason to write too much here on the various topics the book covers (often these brief reviews serve as my mental notes about a book), as I have many pages of handwritten notes I took along the way.

Suffice it to say that this book challenged my previously held beliefs/intuitions in this topic area more than anything else I've read, so much so that I feel I'm making a mockery of my previous self who might have said something similar about another book(s). Luckily, in a very real sense, that previous self was in a very real way different than me! The powerful thought experiments employed by Parfit brought on many first-hand experiences of cognitive dissonance that lingered substantially longer than the fleeting moments we might experience on other occasions, largely because of just how counterintuitive some of the conclusions might seem. It will take more reading and reflection to get a feel to what extent my mind has changed on certain issues, but I'm fairly convinced at this point, at least with the proper Bayesian prior, that more of Parfit's conclusions are likely true than I would like to realize. For anyone with the patience to give this book it's due diligence, I highly recommend. Just be sure to bring you 'A' game!
Profile Image for Henry Cooksley.
159 reviews52 followers
May 25, 2019
This post also appears on Medium and can be viewed here.

(Please note: I would really recommend this for people with at least a year's worth of studying philosophy at undergraduate level or higher; otherwise, I imagine it will be pretty heavy going and I'd recommend other starting points instead! If that doesn't put you off, or you're still interested but not sure if you have the background, I think you could get a lot out of the book by starting with the Concluding Chapter, then picking any individual chapters you think you would enjoy. For example, I think the section on Personal Identity is a bit more intuitive and doesn't have that many prerequisites. Also, the appendix on a Social Discount Rate might be entertaining for those with any background in economics.)

A quote on the back cover says: “Reasons and Persons may be the greatest work of substantive moral philosophy in the Utilitarian tradition since Sidgwick's The Methods of Ethics was published over a century ago.” I'm inclined to agree.

It's taken me a while to get around to finishing this book, having started it nearly five years ago, during my philosophy undergraduate degree. I put it off for various reasons, including the intimidating first few chapters on self-defeating theories, where Parfit briefly enters into metaethics territory. I don't think I was as prepared to read it then as I am now; the major change in between has been the relevance of applied ethical thinking to nearly every aspect of my life, mostly thanks to the effective altruism community. I would guess that effective altruism owes a large part of its existence as an intellectual movement due to Derek Parfit, and specifically due to this book.

Now, a lot of this book reliably feels like it was written in the 1980s at All Souls College, Oxford - the anecdotes and examples, the 'he/him' pronouns as default, some of the general style and language, the unexpected references to Proust and Nietzsche. I would say that basically all of this will be unimportant to those with a true interest in reading and engaging with philosophy from primary sources. This book should change you after reading it, overwhelmingly for the better.

The sort of applied rational-altruistic philosophical worldview that I've lived and breathed for much of the past five years is familiar in these pages. I wonder what would have been different if I had struggled through the intellectual foundations first, before putting the ideas into practice, rather than the other way around. Would I have made different decisions? Potentially. So much of the EA worldview is here: rationalist consequentialist ethics, moral personhood, future generations. Maybe I would have donated differently, e.g. with more emphasis put on the far future. I'd say that the biggest (moral) philosophical thing added to the EA worldview in addition to the Parfitian worldview in the past decade has been the moral uncertainty framework of Will MacAskill and others. I used to think that reading Will MacAskill or Nick Bostrom was the best entry point to the philosophical foundations of the movement. Now I'm not so sure. This book might be it.

Some quotes:

“Until this century, most of mankind lived in small communities. What each did could affect only a few others. But conditions have now changed. Each of us can now, in countless ways, affect countless other people. We can have real though small effects on thousands or millions of people. When these effects are widely dispersed, they may be either trivial, or imperceptible. It now makes a great difference whether we continue to believe that we cannot have greatly harmed or benefited others unless there are people with obvious grounds for resentment or gratitude. While we continue to believe this, even if we care about effects on others, we may fail to solve many serious Prisoner's Dilemmas. For the sake of small benefits to ourselves, or our families, each of us may deny others much greater total benefits, or impose on others much greater total harms. We may think this permissible because the effects on each of the others will be either trivial or imperceptible. If this is what we think, what we do will often be much worse for all of us.”

“Is the truth depressing? Some may find it so. But I find it liberating, and consoling. When I believed that my existence was a 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.”

“When he was asked about his book, Sidgwick said that its first word was Ethics, and its last failure. This could have been the last word of my Part Four. As I argued, we need a new theory about beneficence. This must solve the Non-Identity Problem, avoid the Repugnant and Absurd Conclusions, and solve the Mere Addition Paradox. I failed to find a theory that can meet these four requirements. Though I failed to find such a theory, I believe that, if they tried, others could succeed.”

As a final note, I am grateful to have seen Derek Parfit give one of his last public lectures at the Effective Altruism Global X conference in Oxford in late 2016. It is a tragic shame that Parfit passed away just a few months later. His loss is still felt today.
Profile Image for Taylor Pearson.
Author 3 books723 followers
September 6, 2017
This book was recommended by Patrick Collison (@patrickc) and Sam Harris is the densest, most difficult book I've ever read.

Derek Parfit was a British philosopher who specialised in personal identity, rationality, and ethics. He is widely considered one of the most important and influential moral philosophers of the late 20th and early 21st centuries. This book is his most famous work.

The first half of the book argues against self-interest theory, the idea that each person should seek the outcomes that would make their life go, for them, as well as possible.

Parfit argues that self-interest theory was a "feature" in hunter gatherer society that became a "bug" after the neolithic revolution when societies become larger and more interdependent. This meant your actions could affect people you didn't know so the in-built feedback mechanism you would get that keeps you from directly harming people is no longer effective. For example, if you took some action which unintentionally harmed a good friend, you would see they were harmed, apologize and stop. When your actions harm someone you never interact with, there's not feedback mechanism to stop you from continuing to create harm.

Parfit uses a thought experiment:

Imagine you have 1,000 torturers matched up with 1,000 prisoners.

When we see each torturer beat his prisoner, we are morally repulsed. With each blow, you can see the pain and anguish on the prisoner's face.

Imagine now that instead of directly harming one prisoner, the torturers stands in front of a switchboard with 1,000 switches. Each time a switch is flicked on, it triggers an electrical shock which causes all 1,000 of the prisoners 1/1,000th of the pain they would have experienced from being individually tortured. This scenario is less morally repulsive and we tend to shrug it off because the effect on each person is very small. Observing a prisoner receiving a small shock does not create the same moral repulsion as a prisoner being ruthlessly beaten.

However, when this happens systematically and each torturer flicks a switch, you end up with the same outcome. All the prisoners endure as much pain as if they had been individually beaten.

Parfit argues this is what is happening in the world today. We are plagued by coordination problems where everyone is doing small amounts of harm to everyone else, making us all worse off, without triggering the moral repulsion reflex. As one example, you could imagine a factory which pollutes a river making the water very slightly worse for everyone downstream.

Parfit advances Critical Present Aim Theory, which if you're really curious, I recommend you just read the book because it would take me about fifty pages to unpack (if I am even capable). :)

The second half of the book further attacks self-interest theory by arguing that there is no such thing as "the self" as most modern people conceive of it. Am I, in this moment, more similar to you, in this moment, as I am to "me" ten years ago? Parfit argues I am not and that self is a construction based on a false belief in Cartesian dualism.

Imagine it is possible to surgically meld your brain and body with Napoleon's brain and body. At what percentages do you become Napoleon or does Napoleon become you?

If you go from 50% you/50% Napoleon to 50.1% You/49.9% Napoleon and the only difference is that the resulting person no longer likes to eat tomatoes, does that make the resulting person you, Napoleon or someone else?

Parfit is clearly brilliant and has some great thought experiments to walk you through his arguments, but make no mistake that Reasons and Persons is still a difficult read.

At the end of the day, Parfit largely succeeds in proving the illusions of the self through formal logic, a much different, but complementary approach, to buddhist teachings and meditation.

He offers some suggestions for how we should behave differently if we accept his conclusions which weren't particularly satisfying and many of which I disagreed with in part or whole.

Parfit is a consequentialist, an ethical theory I have historically subscribed to, but have been drifting away from the past few years. Reading Reasons and Persons actually seemed to accelerate that drift.

The biggest thing I took away was from a moving and compelling argument for (future) self-compassion. We are often harder on ourselves than other people, because we believe it is ethical to be mean or hard to ourselves but not others. However, if you accept that future you is a different person than present you in the same way a friend is a different person than present you, you have to agree with Parfit that "We ought not to do to our future selves what it would be wrong to do to other people."

If you really want to think about ethics, consequentialism, and/or self-interest theory, this is the book for you. Part 3 on the notion of "self" being a false construct is both the best part and the easiest to read so you might start there.
Profile Image for laura.
156 reviews133 followers
July 22, 2009
this book reoriented me philosophically, changed my sense of what i can do with philosophy, and named clearly some things i felt strongly but hazily. parfit, by this book, equipped me with new tools, finer ones. i use it as reference material. i keep it at hand.
Profile Image for Miles.
461 reviews150 followers
December 12, 2018
Every now and then, I come across a book that painfully reveals the limitations of my intellect and critical faculties. Derek Parfit’s Reasons and Persons is one such book. This dense, esoteric text coaxed me right up to the cliff’s edge of my philosophical comprehension, and then shoved me off without ceremony. Even so, I had a few intriguing concepts to contemplate on the way down.

Although I probably lack the raw intelligence to grapple appropriately with the structure of Parfit’s arguments, that wasn’t my only hindrance. I studied philosophy as an undergraduate, but belonged to a relatively untraditional philosophy department and received little training in logic and the analytic style. I am ill-equipped, therefore, to parse the “mathy” approach Parfit brings to moral philosophy. Take this passage for example:

"The argument appeals to the fact that S would tell us to make ourselves believe that it is rational to keep our promises, even when we know that this will be worse for us. Call this belief B. B is incompatible with S, since S claims that it is irrational to keep such promises. Either S is the true theory about rationality, or it is not. If S is true, B must be false, since it is incompatible with S. If S is not true, B might be true, but S cannot support B, since a theory that is not true cannot support any conclusion. In brief: if S is true, B must be false, and if S is not true, it cannot support B. B is either false, or not supported. So, even if S tells us to try to believe B, this fact cannot support B." (19, emphasis his)

This line of reasoning is perfectly valid, and even lucid in its fashion. However, it is exactly the kind of writing that makes me want to assume the fetal position and emerge only when all philosophical questions have been resolved and humanity is lounging in the Elysium of Perfect Enlightenment. Reasons and Persons is rife with more and less complicated iterations of the style shown above, and exceeds 500 yawn-inducing pages (including appendices).

Parfit is also fond of wacky thought experiments. These land with varying degrees of impact, but more often than not feel too divorced from real-world circumstances to provide weighty insight. Take his proposition of Two Hells:

"In Hell One, the last generation [of humans] consists of ten innocent people, who each suffer great agony for fifty years. The lives of these people are much worse than nothing. They would all kill themselves if they could. In Hell Two, the last generation consists not of ten but of ten million innocent people, who each suffer agony just as great for fifty years minus a day." (393, emphasis his)

Parfit goes on to explore in great depth the question of which of these Two Hells is less desirable, uncovering along the way some interesting observations about our moral intuitions. But there are two problems with this approach. First, the Two Hells are both so utterly implausible that I immediately become suspicious of any conclusions Parfit draws from their comparison, even if his reasoning is sound. Such conclusions may be valid within the conceptual boundaries of the thought experiment, but does that mean they are equally valid in the real world? I doubt it. Second, most or all of his supportable conclusions could also be reached using scientific evidence, which would bolster their credibility and obviate the need for elaborate logical puzzles that often confuse more than they clarify.

I felt that both of these problems were pervasive throughout the book. In Parfit’s defense, our scientific understanding of moral reasoning is much more developed in 2018 than it was in 1987, but even so that doesn’t reflect well on the book’s longevity. As a reviewer, I can’t in good conscience recommend this book when many or all of the same findings can be accessed elsewhere in more empirically-grounded and reader-friendly texts. Conversely, readers interested in the history of philosophy and/or the analytic tradition will likely find this book both useful and engaging. As far as I can tell, a majority of Parfit’s main conclusions have withstood the test of time, even if they may be in need of minor revision.

As the title suggests, Parfit is concerned with reasons for action and the persons who hold those reasons. His excellent “Concluding Chapter” provides a succinct summary:

"My two subjects are reasons and persons. I have argued that, in various ways, our reasons for acting should become more impersonal. Greater impersonality may seem threatening. But it would often be better for everyone." (443, emphasis his)

To the extent I was able to understand this book, I feel that Parfit succeeded in making his case for a more impersonal way of deciding how we ought to live. In this view, our reasons for acting ought to derive legitimacy from the kinds of experiences we seek (or that we desire for others), rather than from the kinds of persons we perceive ourselves to be. Stated another way, the question of what experience(s) an action is likely to produce takes precedence over the question of what type of person(s) should act in such a way.

Parfit cleverly reveals many flaws in our natural intuitions about personal identity, casting doubt on the longstanding notion that identity formation is the key to ethical living. His “Reductionist View” of the self aligns neatly with modern definitions of personhood developed by psychologists and neuroscientists:

"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." (281)

"On the Reductionist View…It is more plausible to focus, not on persons, but on experiences, and to claim that what matters morally is the nature of these experiences…This principle ignores the boundaries between lives, or the separateness of persons." (446)

Parfit doesn’t deny the physical distinction between human bodies, but does challenge the assumption that this distinction signifies a radical or unbridgeable difference. If experience is the common currency we use to determine the ethical value of an act, each experiencing being has a legitimate position to defend and a perspective from which to advocate. Personal identity, with its tendency to rely on superficial physical features and historical, national, and/or tribal associations, provides no such common currency and often pits one group of persons against another. For these reasons, Parfit’s advocacy for a more impersonal ethics rings true for me.

Another problem Parfit tackles is the thorny issue of our collective contribution to slow-moving catastrophes. By invoking the “Harmless Torturers,” one of the book’s most effective thought experiments, Parfit propounds a form of rational altruism that encourages us to look beyond the immediately-perceptible results of our behaviors:

"In the Bad Old Days, each torturer inflicted severe pain on one victim. Things have now changed. Each of the thousand torturers presses a button, thereby turning the switch once on each of the thousand instruments. The victims suffer the same severe pain. But none of the torturers makes any victim’s pain perceptibly worse." (80)

"When all the Harmless Torturers act, each is acting very wrongly. This is true even though each makes no one perceptibly worse off. The same could be true of us. We should cease to think that an act cannot be wrong, because of its effects on other people, if this act makes no one perceptibly worse off. Each of our acts may be very wrong, because of its effects on other people, even if none of these people could ever notice any of these effects. Our acts may together make these people very much worse off." (83, emphasis his)

Parfit explicitly deploys this thought experiment to help us properly frame some of our most pressing modern problems:

"They [the Harmless Torturers] know that, though none of them makes any perceptible difference, they together inflict on their victims severe pain. There are countless actual cases of this kind. In these cases it is true, of the act of each, that its effects on others are trivial or imperceptible. We mistakenly believe that, because this is true, the effects of our acts cannot make them wrong. But, though each act has trivial effects, it is often true that we together impose great harm on ourselves or others. Some examples are pollution, congestion, depletion, inflation, unemployment, a recession, over-fishing, over-farming, soil-erosion, famine, and overpopulation.

"While we have these false beliefs, our ignorance is an excuse. But after we have seen that these beliefs are false, we have no excuse. If we continue to act in these ways, our acts will be morally wrong. Some may be as bad as the acts of the Harmless Torturers." (444)

In this era of globalization, climate change, and mass social media, never before have so many humans had the ability to perform actions with consequences that are obfuscated or concealed completely. It is easy to argue, as Paul Bloom and Matthew Jordan recently suggested, that contemporary life has made Harmless Torturers of us all.

Reasons and Persons leaves me with little doubt that something positive can be gained by assuming a more impersonal ethics that seeks to prioritize desirable experiences and to minimize harm, especially when the results of harmful behaviors are hidden from direct observation. Still, this is a tough sell for a virtue ethicist such as myself. The cultivation of moral personhood is the central focus of virtue ethics, a practice to which I have devoted a huge portion of my mental energy.

While Parfit’s diminished sense of personal identity may produce more ethical behavior in some circumstances, I continue to believe that the cultivation of virtuous identities can do the same. Ultimately, reasons and identities can both be directed toward moral or immoral ends. We ought, therefore, to approach each ethical challenge as it arises, and be willing to apply impersonal or personalized ethics according to our best guesses about which will produce the best outcome. While depersonalizing our moral calculus may be the ticket in some circumstances (such as professional or political arenas), an intimately personal ethics may be most efficacious in others (such as relations with friends and family).

Putting aside these difficult questions, we can rest assured that Parfit’s embrace of Reductionism exerted a powerful and positive effect, at least for him personally and presumably for many of his readers:

"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 with the lives of others." (281)

This review was originally published on my blog, words&dirt.
Profile Image for Anders.
4 reviews2 followers
January 23, 2012
Reviewing (and even more so, star rating) Reasons and Persons is difficult. Having some basic understanding of utilitarianism, I felt that I could follow Parfit's arguments reasonably well, but this is by no means an easy read. There are four parts to the book, each building on the former. The first one, on self-defeating theories, is a technical and complicated review of theories of rationality and morality. This is my least favorite part of the book, and I would even say that for the "casual" reader, this part could be skipped without very much affecting the enjoyment of the following parts. What I found most interesting about Reasons and Persons is when Parfit starts laying out his arguments for a Reductionist view of personal identity (implying, among other things, that personal identity can be indeterminate, i.e. not all-or-nothing). Thinking about these questions is fairly mind warping and I enjoyed it quite a lot. Building on the Reductionist view, Parfit makes arguments about how we should think about ourselves and others, as well as future generations and our future selves. Most of Parfit's arguments later in the book are based on the Reductionist assumption, which by then is considered "true". As it is a counter-intuitive view, however, some conclusions are difficult to accept. Parfit mentions Nagel's claim that "even if the Reductionist View is true, it is psychologically impossible for us to believe this" (Section 94). Parfit also acknowledges that many may find his conclusions disturbing, while in the case of himself he has found them liberating. All in all, an excellent and thought-provoking, if at times very dense and technical, read.
Profile Image for Josh Friedlander.
716 reviews102 followers
May 24, 2022
Honestly, I found much of this book vapid and disconnected from reality, like the legendary medieval counting of angels on pinheads. My problem is that I read After Virtue first, which inoculated me against all theorising about ethics from first principles; passages like
If we call some theory T, call the aims that it gives us our T-given aims. Call T indirectly individually self-defeating when it is true that, if someone tries to achieve his T-given aims, these aims will be, on the whole, worse achieved.
are in MacIntyre's analogy, like the empty chanting of the priests in A Canticle for Leibowitz, blindly trying to recreate science based on rituals they don't understand. For MacIntyre, moral virtue - all virtues - are inseparably embedded in the lived experience of human culture, and part of our basic understanding of and interaction with the world. In metaethical terms this is probably akin to subjectivism, or (in Isaiah Berlin's term) value pluralism. It is close to my worldview, and, I suspect, close to that of Parfit's hero Bernard Williams.

Parfit emphatically believes in universals, in the commensurability of different ethical beliefs and the possibility of rationally choosing between them. To this end he wields a number of original methods: finding internal inconsistencies as grounds to reject beliefs (weirdly deontological!); considering the broader collective impacts of our actions on others, now and in the future; reducing the focus on the self as a continuous, consistent being (thus his choice between "reasons" for doing things derives partly from his redefinition of "persons"); and an endless stream of annoying thought experiments, ranging from cheesy sci-fi commonplaces (the teleporter that annihilates you and reconstructs you on Mars half an hour later) to the truly deranged:
Suppose that Satan rules the Universe. Satan cannot affect which is the true theory about rationality, or which is the best or best justified theory. But he knows which this theory is, and he perversely causes belief in this theory to have bad effects in this theory’s own terms.
Another especially egregious one involves scientists replacing every cell in my brain and body, one by one, with those of 30-year-old Greta Garbo. (A lot of modern philosophy is the Sorites paradox in disguise.) This is dumb in a specific way - even an exact replica of Greta Garbo, being not "Greta Garbo" but "an existing being replaced cell by cell with Greta Garbo in a lab", would dramatically diverge from Greta Garbo within the first second of awakening - but also in a broader sense, that such an operation is so bizarrely improbable, such a cartoonish reduction of the little we know of neuroscience, that to waste even a second of our short time on Earth considering it feels obscene. (Needless to say, if such an operation becomes available in the future I will need to dramatically revise many of my philosophical beliefs.)

My subjectivist ethics, of course, is susceptible to the same critiques political liberalism makes: it does not afford people with differing moral conceptions a means of persuading each other (something which has occasionally been known to cause problems). But the truth is that even within a single system we are apt to encounter contradictions, unless we select a single value to maximise. This, what G.E. Moore called the naturalistic fallacy, is what many have tried: Bentham suggested pleasure. Parfit quotes Hume that "'tis not unreasonable for me to prefer the destruction of the whole world to the scratching of my finger", and this critique is part of his turn to include in his calculus the world population and future generations, to decentre the self. (Another argument is a somewhat game-theoretical claim that even if one cares only about oneself, an ethical system in which others help each other will yield a better payoff than one in which each of us only look out for ourselves.) Via Peter Singer, and the lay church of LessWrong/Effective Altruism, this has come to have a significant impact on the real world. But Parfit's approach leads to other paradoxes, like the repugnant conclusion (the "downward escalator") wherein we are led to increase the amount of people on the planet until its full capcity is reached, where everyone's quality of life is just barely above preferring death. If we reject this world - and also one in which one couple, Adam and Eve, live a pleasure-filled life and then die childless - then how do we choose the correct amount of people the world should have? Here, as in many other parts in the book, Parfit relies on the "low road" of intuition, but whose intuition? Everything leads us back to subjectivism.

"When he was asked about his book, Sidgwick said that its first word was Ethics, and its last failure." Parfit admits with this quote that his book is a partial failure (as is clear, I think the magnitude of the failure much greater) as he has not sorted out all the questions he has raised. Still, the impact of this book on modern thinking on morality has been significant, and many of Parfit's ideas were already familiar to me from the zeitgeist: the repugnant conclusion (a more plausible refashioning of Nozick's "utility monster"); the wealthy young heir who wants to give away his inheritance to the poor and tells his wife that if he changes his mind when the time comes she should ignore him since he is not the same person; the writer who drives herself to exhaustion, torn between perfectionism and self-care (reader, c'est moi!) And Parfit is optimistic that the field is young and that these problems can be solved: true, humans have been stuck on them for millennia, but the history of nonreligious ethics is much shorter, beginning in earnest only in the 1960s. (Perhaps being in a secular society might lead us to new territory - the book I want to read on this is A Secular Age, it's just very long but I hope to get to it this year.) Only now, also, are we able to measure our interdependence, the long-term effects of our actions on the environment and on future generations.

Some stray thoughts: - If the unity of the self is looser than we think (as Parfit argues), this would imply young people should avoid activities which give them pleasure but will lead to more suffering when they are older, such as smoking or listening to very loud music.

- Which theory of criminal justice explains statutes of limitations? If you don't want to say people over time are different selves, which I don't. I guess it's just not common enough to bother with?

- Parfit's very short argument against moral scepticism: if I am standing where a rock is about to fall, I should move. Therefore people can have reasons for doing things. Therefore, it is possible that there are moral reasons as well.

- The "downward escalator" is a common phenomenon: in fact growing until resources run out and the population suffers is a fundamental fact of ecology. (Something I am well aware of of as a resident of a dense, resource-poor country.) My response to this Malthusian question is usually what Charles Mann call "wizard thinking", the assumption that we will probably find a solution to the problem when it becomes acute. Thus using up resources unsustainably now may not be discounting future generations but merely technological Whiggism.

- Here is a great profile by Larissa MacFarquhar of Parfit, who was definitely what we would call "on the spectrum". "For years, according to a colleague, he made the same meal every morning for breakfast, which he conceived of as a recipe for maximum health: sausage links, green peppers, yogurt, and a banana, all in one bowl. One day, the colleague’s nutritionist wife explained to him that this was not a particularly healthy meal, and suggested a better meal; the next day he switched to the new meal and never varied it."
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March 24, 2023

يذكر الكاتب في بداية الكتاب انه لن يكتب له مقدمة. يقع الكتاب ، في النسخة العربية من إصدار دار معنى ، في ٧٠٠ صفحة ، بالإضافة إلى ثبت مصطلحات إنجليزي-عربي. يمتلئ الكتاب بالمحاجات المفصلة تفصيلا شديدا ، والمرتبطة ببعضها بشكل كبير. قد يتضح الآن ان عدم كتابة المؤلف لمقدمة كان قرارا جيدا ، اذ ان مقدمة لمثل هذا الكتاب كانت ستكون بطول كتاب قصير. ايضا ، قد يتضح الآن مدى صعوبة كتابة مراجعة لهذا الكتاب. لذلك ، لن تكون هذه المراجعة سوى عرض للخطوط العريضة في الكتاب. لا توجد مساحة لاكثر من ذلك ، الا ان تتحول المراجعة لكتاب هي الأخرى.

يمكن تحديد المواضيع الأساسية للكتاب في ثلاثة مواضيع. العقلانية ، الهوية الشخصية ، والأخلاق. وبالطبع، علاقة تلك المواضيع ببعضها ايضا.

المقصود بالعقلانية في استخدام الكاتب ليس المنطقية وقواعد الاستدلال، وإنما مدى اتصاف السلوك والرغبة بانها تصب في حسن الحال ، او جودة الوجود.

اما الهوية الشخصية ، فالمقصود بها العامل الذي يحافظ على وحدة او استمرار وجود الشخص بمرور الزمن. عند الأخذ بالاعتبار التغيرات التي تطرأ على على كل انسان بدءا من طفولته وانتهاءا بموته ، فنظريات الهوية الشخصية تحاول وصف ما يجعل -او لا يجعل- ذاك الشخص هو نفسه طوال فترة عيشه.

يقوم الكاتب بعرض نظريات مختلفة في كل من مواضيع الكتاب ، يعرض المحاجات المؤيدة والمعارضة لكل نظرية ، ويبني على ما يجده النظرية الاكثر اقناعا. في تقديري ، فان الكاتب يتصف بالحياد الشديد في عرضه للمحاجات المختلفة ، وقد وصل به ذلك الحياد للقيام بتخصيص الفصل الاول بالكامل للرد على حجج موجهة ضد نظرية هو ليس على اقتناع بها ، لانه وجد تلك الحجج ضعيفة ، ثم قام في فصول لاحقة بتقديم حججه الخاصة ضد نفس النظرية.

لا اعتقد الكتاب مناسبا لمن ليس معتادا على المواضيع الفلسفية وطرق عرض الحجج الخاصة بها. شخصيا ، فانا على اطلاع جيد بالفلسفة ، واعتبر ان لدي خلفية جيدة عن مواضيع الكتاب ، ومع ذلك فلا ادعي ابدا ان قراءة الكتاب كانت سهلة او اني قد فهمته بالكامل.

تنقسم ابواب وفصول الكتاب كالتالي:

يتحدث الكاتب في الباب الأول (في خمس فصول) عن نظرية المصلحة الذاتية كنظرية عن العقلانية ، ويرد على بعض المحاجات التي يستخدمها بعض الفلاسفة ضدها ، وكذلك علاقتها بالاخلاق الجماعية ومعضلة السجين.

في الباب الثاني (الواقع في اربع فصول) يقدم الكاتب محاجاته ضد نظرية المصلحة الذاتية اعتمادا على علاقة الرغبات بالزمن، وكذلك علاقتها -اي المصلحة الذاتية-بالحاضر والأخلاق.

في الباب الثالث (في ست فصول) يقوم الكاتب في الفصول الثلاث الاولى بمناقشة مسألة الهوية الشخصية ، والنظريات حولها ، ويقدم اسبابه لصالح النظرية الإختزالية. في الفصل الرابع من الباب ، يبين الكاتب اسبابا في صالح اعتبار الاستمرارية والترابط النفسيين اهم من النظرية الاختزالية التي تعتمد عليهما. في خامس الفصول ، يبدأ الكاتب في ربط مسألة الهوية الشخصية بنظرية المصلحة الذاتية ، اما في الفصل السادس فيربط بين الهوية الشخصية والأخلاق.

في اخر الابواب (ويتكون من ثلاث فصول) ، يناقش الكاتب مشكلة تأثير قرارتنا اخلاقيا على الاجيال المستقبلية ، وقد قام بالتركيز على مشكلة استنزاف الموارد ومشكلة التضخم السكاني.

في فصل ختامي يتحدث الكاتب بشكل مختصر عن الهوية الشخصية (مجددا) ، والشكوكية في حقيقية الاخلاق ، والأخلاق بين الدين واللادينية ، كما يطرح سؤال ما اذا كانت استنتاجاته تستحق البهجة ام الاسف ، ويقدم رأيه في ذلك.

وفي عشرة ملاحق ، يعود الكاتب لنقاط معينة ويقدم شروحات جديدة تتعلق بها ، مثل نظرية المصلحة الذاتية ، والعقلانية ، والهوية الشخصية (أجل ، مجددا) ، افضل اسوء الاختيارات الاخلاقية ، ومدى جودة او سوء الوجود واللاوجود.

بالنسبة للترجمة ، فلا املك النص الاصلي حتى استطيع مقارنتها به ، ولكن يمكنني القول ان الترجمة ، من حيث وضوح المعنى وتناسق وتركيب الجمل ، كانت مقبولة جدا وقابلة للقراءة ، مع وجود بعض المواضع التي شعرت فيها بان الترجمة كانت حرفية بشدة او ان اختيار الكلمات كان بلا معنى ، وان كانت هذه المواضع لا تؤثر على المعنى الكلي.


بعد قراءة الكتاب مجددا، قررت خفض تقديري للترجمة من مقبولة الى متوسطة، فمع أنه من الممكن فهم معظم النص المترجم، الا ان الترجمة كثيرا ما كانت حرفية وغير مرنة، واعني بذلك ان المترجم حافظ على اسلوب اللغة الانجليزية في الوقت الذي تحتاج فيه الترجمة للغة أخرى الى تعديل الاسلوب، وليس المعنى، ليناسب اللغة المترجم اليها، مثل ترتيب اجزاء الجمل.

Profile Image for Andrei Khrapavitski.
92 reviews25 followers
February 9, 2017
Just finished reading “Reasons and Persons” by Derek Parfit, a British moral philosopher who passed away on January 1, 2017. It’s been a while since I enjoyed reading a philosophy book so much! It almost feels like the author was some superhuman, Buddha-like impersonal being. This is the kind of book you would want our artificial superintelligent overlords to read so they wouldn’t want to destroy us after reading the Bible, the Quran, Jean Baudrillard, Michel Foucault, etc. There is a vast array of thinkers whose books are enjoyable to read, yes, but lead us nowhere in terms of our understanding of morality and ethics. Parfit makes his best attempt at non-religious, secular ethics. And this book is a masterpiece in its own class, even though it feeds from the immense scholarship of the past carefully studied, questioned, argued for or against through clever thought experiments, some imaginable in our present reality, others purely out of the realm of science fiction.

The book’s cover features the image of Venice. Just as I do, the author loved this city and used it in several of his thought experiments.

The book is divided into four parts. In Part I, Parfit argues against self-interest theories in which humans believed for millennia. He lays ground for a more impersonal moral theory. He would later develop this theme in his following capacious work, aptly titled “On What Matters.”
He extends his arguments against self-interest theories in Part II, where he explores relationship between rationality and time. Ask yourself, for instance, whether your current smoking habit was morally justifiable toward you at a later time in the future. Ask yourself whether your current self (whatever you think it was) is the same as that of you 10 or 20 years ago or 20 or 30 years into the future.
The most famous part of the book is definitely Part III. It is about personal identity. The view of Parfit is in a way what one could call secular Buddhism. Using the now-famous Teletransporter thought experiments and clever reasoning, Parfit argues that any criteria we attempt to use to determine sameness of person will be lacking, because there is no further fact. What matters is simply "Relation R," our psychological connectedness and/or continuity, including memory, personality, and so on.

Part IV is on our responsibility towards future generations. Here we are invited to think whether it can be wrong to create a life, whether environmental destruction violates the rights of future people, and so on. Here we are faced with some serious mind games. I guess some of you might enjoy trying to solve Parfit’s Repugnant and Absurd conclusions and the Mere Addition Paradox. Policy and ethics wise, solutions of these problems are very consequential.

Even though Parfit failed to solve some paradoxes in this book and he did not come up with unified theory of ethics, he continued this work until his death. I believe he left us hopeful. We are on a firmer ground than before in finding better answers to our moral questions. Parfit, together with a number of authors, has reinvigorated my passion for good philosophy. In comparison with the other sciences, as Parfit himself admits, non-religious ethics is the youngest and the least advanced. “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,” he concludes the book. Amen to that.
Profile Image for Ethan.
Author 2 books57 followers
August 18, 2020
A deeply challenging book: challenging to understand even for careful readers, challenging to most of the dogmas of Western analytic philosophy about reasons and persons (while embedded within that tradition), challenging in even subtler ways to initially obvious comparisons with many Buddhist arguments against the existence of a self (Parfit himself probably didn't understand that challenging and complex tradition extremely well, although he didn't claim to). Most of all: it's challenging to review such a long and complex and challenging book, so I'll leave it there.
Profile Image for Jon Norimann.
398 reviews4 followers
February 14, 2017
This is a surprisingly good book. It discusses non-religious moral philosophy, in particular what is a good basis for a persons actions. 3 major hypothesis are getting most of the attention, acting morally good, acting on self interest alone or acting on short term desires. The consequences of these basic rules of action are then evaluated both for long term effects and interpersonal effects.

Parfits style is such that no previous knowledge of philosophy is needed to read the book. Significant parts on teleportation and discount rates give the book an unexpected twist that an audience not normally interested in moral philosophy will like. And this really is a book for anyone, dealing with a basic issue of human life in a new and refershing way.

Reading Reasons and Persons is a good idea for all, giving more insight in your own and other peoples life.
Profile Image for Priya.
93 reviews57 followers
October 8, 2018
It’s 2018 and we still do what we want to do or what we beleive is best to do for us. He takes on each of these approaches and breaks them to failure using thought experiments. Very Dostoevsky like and very John Nash like at the same time. I can’t believe how he managed to pull these two worlds in this philosophical maneuver. Must read for fans of ethics, philosophy and mathematics. And those who loved Brothers Karamazov. It’s the same rigorousness applied to plebeian thoughts.
Profile Image for Jesper Östman.
3 reviews12 followers
October 23, 2009
Read the third part, about Personal Identity and ethics.
A very good, thoughtprovoking and important book.
Profile Image for Nick Klagge.
711 reviews53 followers
August 11, 2017
This is an extraordinary book. It is also challenging and also imperfect. I don't agree with everything Parfit has to say, but R&P has done as much as any book to make me think hard about philosophical issues. (As a side note, I got interested in reading this book from watching Shelly Kagan's Yale course on Death--highly recommended as a more digestible introduction to some similar topics--as well as, unfortunately, from reading about Parfit after his recent death.)

It's difficult to know where to start, without just writing an extremely long (even by my standards!) recap of the book. For me, the most engaging part of the book is the middle section, on personal identity. (This is the part closely related to the Kagan course.) Parfit argues for a reductionist view of the self (no appealing to immaterial "souls" that we don't have any clear evidence to support), and follows this argument through to some counterintuitive and perhaps unsettling conclusions. He works through a number of thought experiments regarding teleportation, brain transplants, and other fanciful scenarios, to develop the conclusions: briefly, that personal identity merely consists of psychological connectedness in terms of memories, intentions, and so forth, and that there is "no further fact" regarding personal identity that we can appeal to. So when you step into the Star Trek transporter, and ask whether you are about to wake up on the planet's surface or whether you're about to die, there is no answer to this question. Although his arguments are based on fairly fantastical thought experiments, I find them pretty convincingly argued. Parfit's view on identity has a very wide range of implications, in terms of both ethical theory and the way we ought to live our lives (and, by extension, the way we ought to think about our deaths). I am far from done thinking about these things. But one main conclusion that Parfit draws out in the book is that the relationship between our current, past, and future selves is more similar than we intuitively feel to the relationship between our current selves and other selves. He draws out this idea in a concrete argument in favor of rules preventing people from behaviors that are too harmful to their future selves. More generally, Parfit's view favors "impersonal" ethical perspectives that are not excessively focused on "the self through time" as a unit of analysis.

The remainder of the book is also interesting, though it was a bit more slow-going for me. His discussion of ethical theories is extensive, yet (refreshingly?) inconclusive. He demonstrates weaknesses in several ethical theories but does not have a ready answer to what might constitute a totally consistent and worthy theory. The last part of the book is an extended discussion of population ethics centering around the "repugnant conclusion" (so dubbed by Parfit)--that based on a set of seemingly unobjectionable premises for a consequentialist ethics, it is difficult to avoid the conclusion that it is better to have a universe of trillions of people with lives barely worth living, than the current universe or indeed any universe with a smaller number of happier people. This is a fascinating thought experiment, and again, while I don't have any clear response to it, it is very thought-provoking.

My first observation is that Parfit seems oddly inconsistent in his willingness to question his intuitions. In the personal identity section, he is willing to accept the "no further fact" conclusion, though he admits he finds it difficult to grasp intuitively, simply because it so clearly follows from premises that he sees as unassailable. Yet he is extremely unwilling to accept the repugnant conclusion, even though the situation is quite parallel. I wonder what accounts for this difference.

I feel compelled to draw the conclusion that the existence of the repugnant conclusion stands as something of a rebuke to humans who would "play god." It may be that it fundamentally makes no sense to argue that hypothetical and totally unconnected universes can be compared to conclude which one is better. (This would be somewhat analogous to the no-answer conclusion on the transporter.) Why should we expect such conclusions to be possible, or indeed, even desirable? The questions are seemingly similar to high-level policy questions regarding, e.g., climate change, which Parfit uses as an example (more or less). But in reality those questions always involve either (a) differential impacts on actually-existing people, or (b) extreme uncertainty around outcomes (or both). Parfit works with examples containing certain outcomes (there will be X number of human lives with Y total utility each), under the presumption that this is a simplifying assumption that brings the key questions into sharper focus. But I'm not sure this is the case. In decisions with world-level consequences, (Knightian) uncertainty seems to be a fundamental and very important aspect, and I'm not sure that conclusions drawn under certainty continue to hold. (Again, we're not gods.)

I think the book also contains some unintentional clues to problems with the repugnant conclusion. Near the very end, Parfit has a discussion of a hypothetical example of generational decision-making, involving some sort of dying-earth scenario (it's been a while since I finished and I don't have the book at hand). The scenario is meant to be a concrete instantiation of the repugnant conclusion. But what interested me was that with the concrete frame, the "repugnant" conclusion came to seem a lot more intuitive and believable. (In part, I think this was because of our natural intuition of uncertainty in concrete cases--there seems to be value in an unending series of barely-worthwhile lives, in part because we have a sense that something good might happen!)

Finally, it might be that, to a god with a "view from eternity" of the world, the repugnant conclusion would be eminently sensible, but also that it does not extend to humans, with our limited perspectives and enormous uncertainty. Religious and mythological writing is filled with the idea that gods might have ideas of justice that are completely unintelligible to us.
Profile Image for lyle.
117 reviews
July 25, 2018
“Consider, for example, clubs. Suppose that a certain club exists for several years, holding regular meetings. The meetings then cease. Some years later, some of the members of this club form a club with the same name, and the same rules. We ask: ‘Have these people reconvened the very same club? Or have they merely started up another club, which is exactly similar?’ There might be an answer to this question. The original club might have had a rule explaining how, after such a period of non-existence, it could be reconvened. Or it might have had a rule preventing this. But suppose that there is no such rule, and no legal facts, supporting either answer to our question. And suppose that the people involved, if they asked our question, would not give it an answer. There would then be no answer to our question. The claim ‘This is the same club’ would be neither true nor false . Though there is no answer to our question, there may be nothing that we do not know. This is because the existence of a club is not separate from the existence of its members, acting together in certain ways. The continued existence of a club just involves its members having meetings, that are conducted according to the club’s rules. If we know all the facts about how people held meetings, and about the club’s rules, we know everything there is to know. This is why we would not be puzzled when we cannot answer the question, ‘Is this the very same club?’ We would not be puzzled because, even without answering this question, we can know everything about what happened. If this is true of some question, I call this question empty . When we ask an empty question, there is only one fact or outcome that we are considering. Different answers to our question are merely different descriptions of this fact or outcome. This is why, without answering this empty question, we can know everything that there is to know. In my example we can ask, ‘Is this the very same club, or is it merely another club, that is exactly similar?’ But these are not here two different possibilities, one of which must be true. When an empty question has no answer, we can decide to give it an answer. We could decide to call the later club the same as the original club. Or we could decide to call it another club, that is exactly similar. This is not a decision between different views about what really happened. Before making our decision, we already knew what happened. We are merely choosing one of two different descriptions of the very same course of events.”

“Lichtenberg claimed that, in what he thought to be most certain, Descartes went astray. He should not have claimed that a thinker must be a separately existing entity. His famous Cogito did not justify this belief. He should not have claimed, I think, therefore I am’. Though this is true, it is misleading. Descartes could have claimed instead, ‘It is thought: thinking is going on’. Or he could have claimed, ‘This is a thought, therefore at least one thought is being thought’. 20 Because we ascribe thoughts to thinkers, we can truly claim that thinkers exist. But we cannot deduce, from the content of our experiences, that a thinker is a separately existing entity. And, as Lichtenberg suggests, because we are not separately existing entities, we could fully describe our thoughts without claiming that they have thinkers. We could fully describe our experiences, and the connections between them, without claiming that they are had by a subject of experiences. We could give what I call an impersonal description.”

“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 a 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. When I believed the Non-Reductionist View, I also cared more about my inevitable death. After my death, there will no one living who will be me. I can now redescribe this fact. Though there will later be many experiences, none of these experiences will be connected to my present experiences by chains of such direct connections as those involved in experience-memory, or in the carrying out of an earlier intention. Some of these future experiences may be related to my present experiences in less direct ways. There will later be some memories about my life. And there may later be thoughts that are influenced by mine, or things done as the result of my advice. My death will break the more direct relations between my present experiences and future experiences, but it will not break various other relations. This is all there is to the fact that there will be no one living who will be me. Now that I have seen this, my death seems to me less bad. Instead of saying, ‘I shall be dead’, I should say, There will be no future experiences that will be related, in certain ways, to these present experiences’. Because it reminds me what this fact involves, this redescription makes this fact less depressing. Suppose next that I must undergo some ordeal. Instead of saying, The person suffering will be me’, I should say, ‘There will be suffering that will be related, in certain ways, to these present experiences’. Once again, the redescribed fact seems to me less bad.”
18 reviews7 followers
January 18, 2022
Holy shit.

This was difficult reading, and entire chapters felt trivial or useless, but this still feels like the most important thing I've ever read.
Profile Image for Marks54.
1,319 reviews1,152 followers
May 11, 2021
We spend a good portion of our time in civilized society telling (or sometimes writing) about why people do things and why and how anything important ever happens. It has long struck me that while such story telling is common, it is unwise to push too hard on the details of these stories or explanations. In certain areas of social science issues of agency are a source of constant bewilderment and even entertainment.

What does it mean to even have a reason for doing something? Is that opposed to having no reason at all? Or is it that we have one reason among many? Or can we do things for multiple reasons at once?

Things do not get clearer if you ask about “persons”. I remember a long time ago when I asked someone who I thought should know what a person was. The response came back swiftly - a person is a responsible agent of action. I did not follow up at the time but wish I did to this day. Responsible? An agent of action? The older I get the more I realized that his answer had just shifted the pieces around into a new puzzle that restated the old puzzle. None of this has gotten any clearer over time (another part of the puzzle by the way).

Most people get over such questions - at least enough to carry on. I had long wanted to see how contemporary philosophy dealt with such fundamental issues and perhaps how it differed from what the psychologists were turning up. It would at least be helpful to see what deep thinking could do on these problems. It was in one of these moods that I ran across the work of Derek Parfit.

Reasons and Persons is an integrated collection of essays on topics related to the fundamentals of how rational humans go about their business. These mostly are logical essays and explorations of ideas about how we act and justify our action. The book has four general areas. I will not attempt to summarize the arguments, even the ones I understand. Readers should work through them on their own. The first section goes over a variety of logics of action but seems primarily focused on showing the weaknesses of arguments for self-interested action. The second part of the book expands to include arguments about action in time. What difference does it make whether we are oriented towards the present, the near term, or the longer term? Does time make any differences in our choices? When would it matter? When would it not matter? The third part of the book spends more time on issues of identity. Who is it that is doing the action? Who is responsible for an action? Why would someone be responsible or not? What if someone is suffering from Alzheimer’s disease? What if someone is facing the onset of a dementia? There are all kinds of thought experiments involving transplantation and teleportation that will bring out nuances in the arguments. Identity presents issues for action and responsibility in lots of ways. The last section of Reasons and Persons is more concerned with action towards a more distant future with consequences to future actors. I found this less interesting but it is worth study on its own terms, for example in light of the improved living prospects of billions in the world due to economic growth in China and India.

None of this does justice to the richness of the book. Parfit passed recently (2017) but I will try to read more of his work. It is well worth the effort. This is difficult material to work through and it is readable enough for analytic philosophy. It is not a quick read but it will likely pay dividends for working through the material.
Profile Image for Bracton.
293 reviews8 followers
October 2, 2014
I'm finished with this book. I've been reading it for ages and I can't take the slog any more. By all accounts Parfit is a genius and this book has been hugely influential but for me it felt like an abstract, fastidious, and pedantic exercise, by someone more akin to an alien logician than a human being.
Profile Image for David Gross.
Author 12 books99 followers
June 15, 2010
I only got a quarter of the way in to it or thereabouts and was bored the whole way, so I gave up. I understand that this has been a terribly inspiring book to many people, but I thought it was poorly-written, deadly-boring, wordy, and off-putting.
Profile Image for Ryan Morrow.
Author 7 books13 followers
October 8, 2022
This was an incredibly challenging book as advertised. I listened to it as an audiobook which allowed me to get through some of the more dense material. Not sure I could have finished it within a reasonable time frame if I only had access to the hardcopy.
That said, I think it’s an incredibly important topic and necessary material. Parfit’s masterwork on “what is ethics” without religious doctrine. In the end it feels almost like a mathematical proof or at least supreme systematic breakdown of ethical thinking.
If nothing else this was worth all the critical thought experiments. What is better: situation A or B given XYZ. I gave it 4 stars instead of a 5, only because it was so damn grueling at times. But that’s more of a testament to my intellect and stamina than Parfit’s writing ability or philosophical discourse.
Profile Image for Hailong Hao.
273 reviews86 followers
May 21, 2020


对我自己而言,这本书带给我最大的价值是让我对 Personal Identity 的重要性有了一个全新的认识,或者说他用最清晰的方式重新塑造了我的人生观。而在有了这种新的人生观之后,你的价值观也会跟着发生改变。

Profile Image for Luke.
847 reviews14 followers
September 18, 2017
Clearly a classic on confronting self-interest from a reductionist perspective. Straight-forward thought experiments and argument. But took me 3 tries over 4 years to finish, and admits optimistic defeat in the end.
Profile Image for Esther Kemball.
9 reviews6 followers
September 6, 2018
I actually finished this book several months ago, except for the appendices, but I didn't want to mark it as read until I had done those and I kept putting them off.

This is an excellent book which I would recommend to everyone who has the spare time to read it. I can't say much about it that hasn't been said, but I just want to recommend it very heartily.
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