The Non-Identity Problem

· Philosophy


The philosopher at work.

© Klaus Rohde


The non-identity problem, according to the Stanford Encyclopedia of Philosophy: “probes some of our most intuitive beliefs regarding the moral status of acts whose effects are restricted to persons who, at the time the act is performed, do not yet but will exist…….”. What is the “the structure of moral law: is it “person-affecting” in nature or is it “impersonal” in nature? Can………. an act that affects no person who does or ever will exist for the worse be wrong? Or is the wrongness of any particular act dependent (at least in part) on something beyond what that act does, or can be expected to do, to any such person?”.

Two posts in my blog reproduced below with considerable deletions and modifications deal with the problem. I emphasize, however, that they do not attempt to give an exhaustive and deep discussion of the problem, but are meant to stimulate discussion. Previous comments on my posts are also included. For full details of my posts see here and here.

Readers who do not want to become involved in philosophical discussions which may appear to them as not much more than hairsplitting, may wish to skip the first part (The Non-Identity Problem) and go straight to the second (The Non-Identity Problem, as Seen by a Postmodern Pop Artist).




Derek Parfit, an English philosopher, has formulated the non-identity problem in his book “Reasons and Persons” [1]. The problem is thought to be important in bioethics, helping us to judge about the morality of actions that may affect future generations. In the following, I use parts of the summary of John Nolt to critically examine some of the points made by Parfit. My comments in bold and italics. Parfit draws attention to paradoxes arising from various assumptions. The problems discussed are certainly important, with consequences for environmental policy and population control, among others. For example, it may affect our decisions on which actions to take to prevent climate change, or whether to permit euthanasia.

Summary of Parfit, Chapters 16-17 by John Nolt (“extracts”) and my comments


In chapter 16 two closely-related ideas are discussed:

“(1) the fact that the identities of those affected by our choices may be altered by the choices we make (that is, different people may come to exist if we make one choice rather than another), and
(2) the problem of constructing a true moral theory………..that is adequate to deal with this fact.”
(ad 1): I thought it is self-evident that many of our actions, often very small and unintentional ones, may affect who comes into existence later. But does it matter? Is it really important who comes into existence, as long as somebody does? We have no or little control over most of our actions, consequences of our actions are often non-intentional, and therefore not subject to moral judgments. Even if some of our actions are so significant and strong that they must have some important effects on future generations, we have no way of assessing what future generations would have looked like without our input.
(ad 2): From the last sentence of my comment on (1) it follows that a “true moral theory” dealing with “the fact that the identities of those affected by our choices may be altered by the choices we make”, if at all possible, will not be able, in principle, to cover a large and possibly the largest part of our actions.

According to Parfitt, “With regard to (1) …….. a large-scale public policy may in a couple of centuries so change the course of events that no one will exist who would have existed had a different policy been adopted. This follows ……. from: The Time-Dependence Claim: If any particular person had not been conceived within a month of the time when he was in fact conceived, he would in fact never have existed…..” Why within a month? Certainly even a second may make all the difference, because different sperm would almost certainly be involved. In other words, we have no control whatsoever about which specific person will be born. …………… “Parfit also assumes that one could not have been conceived by parents other than one’s actual parents. ……….. These necessary auxiliary assumptions seem plausible.” It is true, of course, that different parents could not have produced me, but the same parents may produce different offspring, not only because the genes in eggs and sperm differ, but also because the time of conception and birth are important. A baby is likely to be very sensitive to its first experiences in the womb and after birth (compare the imprinting of birds: probably not as clear-cut in humans, but nevertheless of some importance). Or take the example of identical twins: they are indeed very similar, but still different identities. Not only the genes, but the environmental conditions guiding the expression of genes, are important in forming the character of a person. But even if environmental conditions are practically identical, the fact of spatial separateness would still make them different identities.

Three kinds of moral choice

According to Parfit, there are three kinds of moral choice:

1) Same-people choices: “The same people will have existed regardless of which action we take…..”
Many of one’s actions will not affect who will come into existence, but many others will, and many of them unintentional and beyond our control.
2) Same-number choices:  “Different people will have existed if we take one action rather than others, but their numbers will have been the same ….”
Same comment as for previous.
3) Different-number choices: ” Different numbers of (different) people will have existed depending on our choice…..”
Same as for last two points.

“Traditional moral thinking usually concerns same-people choices……… But moral thinking about future generations usually concerns different-number choices. Same-number choices are an intermediate case. ……..”

The appropriate moral principles for same-number choices are:

“The Same Number Quality Claim: If in either of two possible outcomes the same number of people would ever live, it would be worse if those who live are worse off, or have a lower quality of life, than those who would have lived…..” We do not have any real control over who might live and who might not and

“The No-Difference View: It makes no difference to the morality of an act whether the same people or different people will have existed if we act otherwise……” As for last point ………

The Same Number Quality Claim and the No-Difference View………. are in conflict with a possible alternative, i.e., the

…..”Person-Affecting View …..: It will be worse if [specific] people [who would exist no matter what we choose] are affected for the worse……. i.e., if choice C1 is between outcome A and outcome B happening to the same people and choice C2 is between outcome A happening to one set of people and outcome B happening to a different set, and if outcome B is the worst of the two, then B is worse if it results from choice C1 rather than from choice C2……”

We use two hypothetical examples to illustrate these alternatives.

1) “Depletion vs. conservation: If a policy of depletion is adopted, the quality of life might be somewhat better for everyone for a few hundred years than under a conservation policy, but later it would be much worse. Parfit assumes that after a few hundred years of a policy of depletion an entirely different population would exist than under a conservation policy. Therefore, depletion benefits those who live for the first few hundred years and is worse for no one born later (since without the policy these people would not have existed). It is therefore worse for no one” (At first glance this statement seems to be nonsense. Are those people who do exist – although they are not the same as those who would exist without our actions – not worth considering? Furthermore, we have absolutely no control over exactly who will exist, whatever we do). (However, the Same Number Quality Claim implies that depletion is wrong, whereas  the Person Affecting View implies “that conservation is wrong because depletion is worse for no one, but conservation is worse for those who live in the first few hundred years.”)
2) Two medical programs: “Two proposed medical programs have identical costs and effects, except that one would cure 1000 already existing fetuses of a handicap, while the other would instead of curing these fetuses prevent the same handicap in 1000 people yet to be conceived………”

These examples, according to Parfit, “show that we should accept the Same Number Quality Claim and the No-Difference View and reject the Person-Affecting View. If so, then we have sound principles for dealing with same-number choices. That is the main point of Chapter 16.”

John Nolt, however, concludes that in spite of the intuitive appeal of Parfit’s idea, the argument is not conclusive, there may be other ways of justifying a particular policy. And indeed, Parfit considers one other justification: “that depletion is bad not because it lowers the general quality of life but because it violates the rights of future generations” although there are……….”at least two problems with this claim. One is that it is not obvious that future generations have a right to a high quality of life ……….” (I would think that this really is an obvious postulate). The second problem is that we can hardly be said to be violating the rights of people by depleting the resources available to them if the only other option (as in Parfit’s example) is that they never exist. People’s rights cannot, in other words, be violated by a policy to which they owe their (reasonably worthwhile) existence.”

Finally, Parfit draws a preliminary conclusion about the desired theory …. Many moral theories evaluate an action as better or worse only insofar as it is better or worse for the people whom it affects. Parfit characterizes such theories as having a person-affecting form ……….. Parfit argues that the correct general theory …. will not have a person-affecting form. He claims that this conclusion follows from the No-Difference View together with the assumption that to cause to exist is not a benefit.” Reasons are as follows:

(1) “It makes no difference to the morality of an act whether the same people or different people will have existed if we act otherwise. (No-Difference View)”
This does not make sense. How can we possibly know whether the same or different people will exist in the future (see above)
(2) “Causing to exist is not a benefit.

(3) There is a unique true theory……

So (4) The true theory …….. will not have a person-affecting form (i.e., will not consider an action as better or worse only insofar as it is better or worse for the people whom it affects)………

………if we assume that causing to exist is not a benefit, then the only remaining way in which an act might be better or worse for a person whom it affects is if it is the result of a choice in which this person would have existed regardless of what we chose. This seems hairsplitting to me. As above: we do not know how our actions can affect the existence or non-existence of future people. Hence (still assuming that causing to exist is not a benefit), any true theory with a person-affecting form will evaluate an act as better or worse only if it is the result of a choice in which the same people would exist regardless of what we choose (same-person choice). As above: we have little control over who will exist. Therefore: …… If causing to exist is not a benefit, then any true theory with a person-affecting form must imply that it makes some difference to the morality of an act whether the same people or different people will have existed if we act otherwise. “As for our very ability to evaluate the act morally will depend on whether the same people or different people will have existed if we act otherwise…………..”


Chapter 17: The Repugnant Conclusion

In different-number choices, the problem arises “that in large populations, each additional person born may lower the quality of life for all (due to overcrowding, competition for limited resources, etc.). But the total quality of life that that additional person enjoys may nevertheless outweigh the total loss of quality of life to everyone else. If so, ……… it is better for the population to increase, even though that increase may lower everyone’s quality of life, even to a level at which it is barely worth living. But this conclusion seems paradoxical and absurd. Parfit therefore calls it The Repugnant Conclusion. The principle that engenders the paradox is:

The Impersonal Total Principle:

it means, assuming that other things are equal, “the best outcome is the one in which there would be the greatest quantity of whatever makes life worth living” such as happiness………. which is the classic utilitarian idea that maximal happiness is desirable. The Repugnant Conclusion is supposed to show that classical utilitarianism or other theories based on the Impersonal Total Principle cannot be the true moral theory, because they imply the absurd Repugnant Conclusion in certain different-number choices involving population growth: in a growing population it is possible that the total quality of life increases whereas the average quality of life (quality per person) decreases. In order to avoid The Repugnant Conclusion, we might suppose that it is average quality of life that matters. In doing so we could base the desired theory on

The Impersonal Average Principle:

……… “the best outcome is the one in which people’s lives go, on average, best……..” . But Parfit later shows that this principle also is paradoxical.

Considering all my previous comments, it seems to me that many of the ideas related to the non-identity problem are somewhat obscure. Who can possibly know how most of our actions will affect who will be in existence in the future and who will not. Most of our actions are unintentional, but nevertheless may have immense effects on what will happen. Remember the butterfly effect! Furthermore: it seems to me quite irrelevant to base moral judgments on whether the “same” or different people will be affected by our actions. The reason: we do not know and cannot know in principle what a future person or a future population would look like without input from our actions. All we can hope for is that important personal or government actions will make it likely that future conditions are beneficial to mankind as a whole. And this includes policies which guarantee that resources on Earth are never over-exploited. —- Finally, in a discussion of the non-identity problem (at a seminar in a Philosophy Department) the question was raised whether a cat who by means of some treatment had acquired human mental powers, would qualify for the same moral considerations as humans. Of course it would: it would be human! —- This leads to another point: the discussion of non-identity seems to be restricted to humans (but I may be wrong on this, I am not familiar with most of the literature). I conclude with Schopenhauer:

“Die vermeintliche Rechtlosigkeit der Tiere, der Wahn, dass unser Handeln gegen sie ohne moralische Bedenken sei, ist eine geradezu empörende Barbarei des Abendlandes. Die Tiere sind kein Fabrikat zu unserem Gebrauch. Nicht Erbarmen, sondern Gerechtigkeit ist man den Tieren schuldig.
The supposed rightlessness of animals, the delusion that we can act towards them without moral scruples, is a really disgusting barbarity of the Western world. Animals are not constructs for our use. We owe them justness and not mercy.”

Schopenhauers moral philosophy based on compassion with the suffering of animals and man, appears to be a sounder basis of ethical judgments than the hairsplitting related to the non-identity problem. But I repeat: I know very little of the literature and put this post up as a basis for discussion, and only that. (see here) [2].


6 Responses to “The Non-Identity Problem”

  1. Chris Fellows Says:
    May 13th, 2008 at 11:52 am I thought about this a couple of years ago and was going to write a story based on an invasion by alien nanomachines- their mission, to make everyone and everything ecstatically happy and then, while maintaining this condition, dissassemble everything and reassemble it into the smallest entities capable of being ecstatically happy. The alien nanomachines were going to first manifest as a weight-loss product in a supermarket in New Zealand.

    I think of this possible story and the musings of Parfit as a reductio ad absurdum of the idea that ‘happiness’ or ‘quality of life’ is the supreme good. Life *is* suffering, and while reducing suffering is a good, it cannot be what is most important.

    I am no philosopher, of course. :P

  2. Bill McDonald Says:
    May 13th, 2008 at 1:53 pm I agree with you Klaus, and with Schopenhauer, that the focus of the non-identity problem is quite misplaced and amounts to little more than hair-splitting. Ethics should be focused on building up love and compassion for all sentient creatures, regardless of their “identities”. At best the non-identity problem and its ilk could be used by technocrats to make policy decisions, but it would be a sorry day if such “thought-experiments” were the primary resource for individuals face-to-face with real ethical problems (both their own and others’). I find it hard to imagine that a pregnant woman, faced with the choice of an abortion, would seriously consider for a second the idea of “people seeds” which might grow in her carpet or whether it would be the same person born if she were to abort now and re-conceive four years later. Instead, she would face anxiety, guilt, grief, conflicts between egotistical desires and obligations towards others, social pressures (probably for and against abortion), and perhaps conflicts between secular and religious beliefs. An ethic of care towards her would involve helping her to clarify her emotions, to attain equilibrium, to support her to make whatever decision ultimately is best for her to live with, and to support her after her decision (either to offer emotional and practical support in her child-raising, or to offer her emotional and practical support in overcoming her feelings of grief and guilt and loss). Consideration of philosophical problems such as the non-identity problem would offer none of this practical support, and in fact would distract her from gaining emotional and spiritual clarity by interposing a wall of abstract intellection. Consideration of the non-identity problem by someone else, who then tries to use the results to persuade the pregnant woman either for or against an abortion, would I think amount to an abuse of power. She needs understanding, compassion, love, respect, support, practical help in the real world (as opposed to fantastical help in a theoretical world), and recognition that it is an important decision to be made in a limited time-frame. I don’t rule out introducing philosophical concepts and ideas, and perhaps even thought-experiments, in the process of helping her clarify her feelings, but this should only be done in a spirit of love and compassion and respect for her. Otherwise it becomes a distraction, or badgering.

    This presupposes that the real ethical decision is to be made now or in the near future. There might be a more robust role for critical reflection on these decision after the fact. Even then, I think philosophical nit-picking should be subordinated to the emotional and spiritual needs of those participating in the discussion (especially if any of them has actually had an abortion – or faced whatever the specific ethical decision was). Otherwise it is at best a glass bead game, at worst a means of bludgeoning others intellectually.

    What I did find right in your paper Adrian, was your emphasis on having some sort of nomic constraint on the possible worlds to be considered in thought experiments. However, since I advocate an ethic of care, based on emotional and spiritual understanding, that constraint should be stated in terms of emotional “laws” rather than in terms of physical laws. Cheers, Bill

  3. Chris Fellows Says:
    May 20th, 2008 at 10:35 am “Two proposed medical programs have identical costs and effects, except that one would cure 1000 already existing fetuses of a handicap, while the other would instead of curing these fetuses prevent the same handicap in 1000 people yet to be conceived.”

    Would it not be better to simply replace the word ‘fetus’ in this sentence with ‘person’? A fetus is not a ‘potential person’, but a person near one end of the process of human being. The characteristics that define them as a unique individual already exist- they are not potential, only implicit, and given time alone will become explicit with no interference from us.

    So what I am saying is that I think the Non-Identity problem is of no relevance to any abortion question.

  4. UNE – Klaus Rohde: Science, Politics and Art Says:
    June 4th, 2008 at 12:37 pm […] In a previous post I discussed the non-identity problem. […]
  5. Aurelio Says:
    June 6th, 2008 at 5:26 pm Aurelio

    Ordinary people believe only in the possible. Extraordinary people visualize not what is possible or probable, but rather what is impossible. And by visualizing the impossible, they begin to see it as possible.

  6. Klaus Rohde Says:
    June 14th, 2008 at 5:10 pm THIS SEEMS TO MAKE SENSE:

    Rivka Weinberg 2008. Identifying and Dissolving the Non-Identity Problem
    Philosophical Studies 137, 3-18

    Abstract: Philosophers concerned with procreative ethics have long been puzzled by Parfit’s Non-Identity Problem (NIP). Various solutions have been proposed, but I argue that we have not solved the problem on its own narrow person-affecting terms, i.e., in terms of the identified individuals affected by procreative decisions and acts, especially future children. Thus, the core problem remains unsolved. This is a nagging concern for all who hold the common intuition that actions that harm no one are permissible. I argue against Harmon’s and Woodward’s direct, narrow person-affecting solutions, and in favor of a new solution to the NIP. My solution, or, rather, dissolution, is based on the argument that merely possible people, i.e., hypothetical people who could possibly, but will not actually, exist, are morally irrelevant. I show that the NIP only arises when we concern ourselves with merely possible people. Once we are careful to restrict our concerns to only those that do or will exist, the NIP is dissolved.



Here I present examples illustrating three aspects of the Problem discussed above.


One problem raised in a seminar on the Problem was whether a cat, which – by some as yet undiscovered procedure – would have acquired human mental abilities, should be given the same moral considerations as humans. Look at the pictures: “cats” in the upper and genuine “humans” in the lower row. Aren’t the little “human” cat and her family sweet? After all, the supposed great mental abilities have led to some other, more “human”, changes as well. Do you recognize any significant differences between the two groups except for the bigger ears in the “cats”? Would you agree that, in spite of the big ears, they are as sweet or sweeter than the family in the second row, entirely human derived ? But does this qualify them for humane treatment? What makes a being human? And do only human beings qualify for moral considerations and humane treatment?

small-wom2.jpg small-wom1.jpglittle-w3.jpg small-wom5.jpg small-wo2.jpg small-wo1.jpgsmall-wo3.jpgsmall-wo4.jpg

© Klaus Rohde


An important assumption of the non-identity problem is “the fact that the identities of those affected by our choices may be altered by the choices we make (that is, different people may come to exist if we make one choice rather than another)”. Quite true, of course, but how many of the perceived changes are indeed the result of intentional actions subject to moral judgments? Look at the possible outcomes of fairly minor genetic alterations:

man-e1.jpgman-a2.jpg man-b2.jpgman-c2.jpgman-d2.jpg

© Klaus Rohde


Well, how many mutations were involved? – Probably not many, and none of them deliberately induced. And don’t forget: many mutations are pleiotropic, i.e., they cause not a single change, but many. Are all these representatives of possible future generations simply freak accidents in evolution? Which of the types qualifies most for our moral considerations? Which one do we want to populate the future Earth? These freaks cannot even agree on the type of favorite ball game: on the left the most primitive of the games, rugby, on the right one not yet seen in the recent world, but what does it matter: all players seem to be quite happy with their particular toy.



what is the better outcome: 50 billion people on Earth living just above the existence minimum, but most people still better off than if they were non-existent? Or: 10 billion people living a much “happier” existence? Or : Adam and Eve in the Garden of Eden, even happier? A decision is difficult. If we want to maximize “happiness”, do we chose the greatest “total” happiness (50 or 10 billion people), or the greatest “average” happiness (Adam and Eve, if they are or were indeed happier). Too complicated for me. I leave the decision to the professor below who is ruminating about the Problem.


© Klaus Rohde


But don’t forget, the decision to limit population numbers and the criteria on which the decision is based, may affect you: you or your direct offspring may not be among those chosen to survive!

2 Responses to “The Non-Identity Problem, as Seen by a Postmodern Pop Artist”

  1. Chris Fellows Says:
    June 5th, 2008 at 2:15 pm Welcome back! There is of course nothing magical about humans. And I think this non-identity problem is just a nice demonstration that ethics based on ‘maximising happiness’ are silly.
  2. vince Says:
    June 10th, 2008 at 4:47 am My cat’s are human, and cute will always humanise creatures. Corrigan “Sociology of Consumption” talks on how our pets and animals we work with such ashorses; are sacrosanct as far as being a food source. (situations of survival overcome this reticence, but can go wrong, as in the case of antartic explorers who ate dog livers and suffered negative effects due to a build up of something in them unique to dogs. Hawianns eat dogs, but only ones not fed meat (Corrigan), so maybe eat meating in dogs is the cause of toxins?
    The hippies were produced by anti corporate mentality. The public despised them and denied them economic security, so they were forced to become educators and public servants. The hippy thoughts of caring and respect, were institutionalised to become the political correctness that stops us being spontaneous humans. Social processes produce new humans and social processes, that make new humans etc ? On an individual level, the sad childhood producing a serial killer?
    Population is a product of environment, which is influenced by population; sustainability of numbers, correlating to std of living and “societal happiness”. This happiness is neoliberal inspired in our world ,where economic prosperity, advanced technology and management of people/resources,greed, are welded to democracy; to produce an objective McHappy picture. This is taken up by the population, who equate happiness with money; destroy the environment and other people in the process.
    Sustainability is threatened and brings to the social consciousness a remembrance of a time when there was an “individual happiness”. Priority for existence moves in response, from an objective economic ideology, to a subjective perception where the “greed” , is for a std of living where mental and physical needs are met. A growth in interest in culture, tradition, human rights, poverty, personal well being occurs. But its all on SBS and Foxtel or costs just $13/ month, people can ignore the dead people if they are happy with their political correctness and their cats.
    I am “freak” number 3! lol vince


I wish to thank John Nolt for permission to use his summary.

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