The Non-Identity Problem

Author: Duncan Purves
Category: Ethics, Metaphysics
Word Count: 1000

Consider the following scenario:

Wilma is interested in having a baby. Wilma’s doctor tells her that she has a condition such that if she conceives now, any child she conceives will suffer from incurable blindness.

However, her doctor also tells her that this result is not unavoidable. If Wilma waits to conceive, and instead takes a pill every day for two months prior to conceiving, then she will conceive a child who is not afflicted with incurable blindness.

Had Wilma waited and taken the pill, she would have conceived and given birth to a perfectly sighted boy she would have named ‘Rocks.’

However, she decides not to take the pill in favor of conceiving immediately. As a result, she conceives and gives birth to an incurably blind baby girl. She names this child ‘Pebbles.’1

Typically, we can criticize morally wrong actions by citing their effects on individuals who existed prior to the performance of the action. For example, if Smith steals Jones’s wallet, Jones, a person who already exists, is clearly the one who suffers the harm. The wrongness of this kind of action can be straightforwardly explained in “person-affecting” terms. Normally, a wrongdoer’s act causes an existing person to suffer in some way, or that act violates an existing person’s rights. In these cases, we can identify someone who has been wronged by the action.

In the above case, however, Wilma’s action appears to elude moral assessment using person-affecting moral principles. It appears that Wilma has obviously done something morally wrong by conceiving Pebbles now rather than waiting two months and then conceiving Rocks.

But one feature of the case, which may not be immediately obvious, seems to stymie this conclusion: Had Wilma waited to conceive, Rocks rather than Pebbles would have come to exist. Pebbles would not have come to exist at all, and so Wilma’s act of conceiving Pebbles now does not harm or wrong Pebbles. Let us focus on this claim for a moment.

1. How Can an Action Be Identity-Affecting?

In order for the above problem to rear its head, it must be the case that Pebbles and Rocks are distinct individuals. What reasons are there for thinking that Pebbles is not the same individual that Rocks would have been?

Perhaps the best reason is that one’s identity appears to be tightly dependent on the timing of one’s conception. An example should suffice to make the point. Suppose my parents had waited a year before becoming pregnant: the child who would then have been born—call her Zoe—would not be Duncan.

To see this, note that it is possible for my parents to have had both children: Zoe could be born a year after the birth of Duncan, and then she and I would be brother and sister. But this also entails that Pebbles is not identical to Rocks, because it is possible that Wilma conceives both Pebbles and Rocks, that they are sister and brother.

2. The Non-Identity Problem

If Pebbles is not the same individual that Rocks would have been had Wilma waited two months to conceive, then it is difficult to explain in person-affecting terms why it is wrong for Wilma to conceive Pebbles now rather than to wait two months (and then to conceive Rocks). After all, Pebbles will have a life worth living, despite her disability. Her life will not be worse than non-existence. But if Wilma had waited two months prior to conceiving, Pebbles would not have had a life at all. She would never have come to exist. Rocks would have existed in her stead.

So it seems that Wilma’s act of conceiving now does not make Pebbles worse off than she otherwise would have been, and so it does not harm her. But if Wilma does not harm Pebbles by conceiving her, then it appears that Pebbles has no complaint against Wilma.

In response to any complaint, Wilma can avail herself of the reply that she gave Pebbles the only life she might have had. Therefore, if Wilma’s action is wrong, its wrongness cannot be explained in straightforward “person-affecting” terms.

3. Solutions to the Problem

In what way, then, does Wilma act wrongly by conceiving now rather than waiting? Providing a satisfying answer to this question is the challenge that constitutes the Non-Identity Problem.

Some authors have argued that a person need not have been made worse off than she otherwise would have been to have a legitimate complaint about having been wronged or harmed (cf. Harman 2004; Shiffrin 1999; Woodward 1986). For instance, if I go around in a helicopter, dropping gold bullion onto poor villages in a developing nation, I surely harm (and thereby wrong) the person whose arm I crush with a brick of gold, even if they are benefitted all-things-considered by my action (Shiffrin 1999: 127). The brick of gold that they now possess can more than pay for mending a broken arm, but that does not justify my act. Perhaps then, Pebbles is similarly wronged by Wilma’s act of conceiving her, even though Wilma’s act does not leave Pebbles worse off than she otherwise would have been.

Others have taken the Non-Identity Problem to be evidence that the wrongness of some actions simply cannot be explained in person-affecting terms (cf. Brock 1995; Buchanan, Brock, Daniels and Wikler 2000: 249; Peters 2009: 325; Savulsecu 2001; and Steinbock 2009: 172, 174; 2011: 90). These authors conclude that some acts are wrong even though they do not wrong any particular individual. Still others have argued that we should simply accept the conclusion of the Non-Identity Problem, and revise our judgment that Wilma acts wrongly by conceiving Pebbles (cf. Boonin 2008; Heyd 2009).

4. Conclusion

The solution to the Non-Identity Problem is not obvious, and the Problem itself is not a mere puzzle for academic philosophers to ponder. The solution we settle on (if we settle on one) will have important implications for an array of applied ethical issues that appear to face the Non-Identity Problem. For example, many arguments against human cloning appeal to the thought that the resulting clone might be harmed by the procedure that is responsible for her existence (cf. The President’s Council on Bioethics 2002). But the Non-Identity Problem undermines such arguments. Without a solution to the Non-Identity Problem, we might question whether the common moral aversion to reproductive human cloning is well supported.


This case is modified from Boonin (2008, pp. 127-128).


Boonin, David. 2008. “How to Solve the Non-Identity Problem.” Public Affairs Quarterly vol. 22(2).

Brock, Dan W.  1995.  “The Non-Identity Problem and Genetic Harms — The Case of Wrongful Handicaps.” Bioethics, vol. 9, nos. 3-4, pp. 272-75.

Buchanan, Allen. E, Brock, Dan W., Daniels, Norman, and, Wikler, Daniel. 2000. From Chance to Choice: Genes and Social Justice. Cambridge: Cambridge University Press.

Harman, Elizabeth. 2004. “Can We Harm and Benefit in Creating?” Philosophical Perspectives, vol. 18, pp. 89-113.

Heyd, David. 2009. “The Intractability of the Non-Identity Problem.” M.A. Roberts, D.T. Wasserman (eds.), Harming Future Persons: Ethics, Genetics, and the Non-Identity Problem, International Library of Ethics, Law, and the New Medicine.

Parfit, Derek. 1984. Reasons and Persons. Oxford University Press.

President’s Council on Bioethics. 2002. “Human Dignity and Human Cloning An Ethical Inquiry.”

Savulescu, Julian. 2001. “Procreative Beneficence: Why We Should Select the Best Children.” Bioethics, vol. 15, no. 5-6, pp. 413-426.

Shiffrin, Seana Valentine. 1999. “Wrongful Life, Procreative Responsibility, and the Significance of Harm.” Legal Theory, vol. 5, pp. 117-148.

Steinbock, Bonnie.  2009.  “Wrongful Life and Procreative Decisions.”  In Roberts and Wasserman, eds., Harming Future Persons. pp. 155-78.

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About the Author

Duncan Purves is an Assistant Professor in the Philosophy Department at the University of Florida. His research explores ethical theory, bioethics, and environmental ethics, focusing especially on emerging technologies, the normative significance of harm, death, and our obligations to future generations.

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