Genes, Embryos, and Future People

GENES, EMBRYOS, AND FUTUREPEOPLE

WALTERGLANNON

ABSTRACT

Testing embryonic cells for genetic abnormalities gives us the capacity to predictwhether and to what extent people will exist with disease and disability.Moreover, the freezing of embryos for long periods of time enables us to alter thelength of a normal human lifespan. After highlighting the shortcomings ofsomatic-cell gene therapy and germ-line genetic alteration, I argue that thetesting and selective termination of genetically defective embryos is the onlymedically and morally defensible way to prevent the existence of people withsevere disability, pain and suffering that make their lives not worth living forthem on the whole. In addition, I consider the possible harmful effects on childrenborn from frozen embryos after the deaths of their biological parents, or when theirparents are at an advanced age. I also explore whether embryos have moral statusand whether the prospects for disease-preventing genetic alteration can justifylong-term cryopreservation of embryos.

INTRODUCTION

Recent advances in reproductive biotechnology have given us theability to intervene in the process of human biological developmentfrom embryos to people. One type of intervention is the testing ofembryos for genetic defects that cause disease, which enables us tochoose between allowing these embryos to result in disabled peopleor selectively terminating their further development. Alternatively,in the foreseeable future it may become possible to prevent disease bycorrecting a mutation in embryonic cells or by inserting a normalgene into these cells. It evenmay become possible tomanipulate genesin such a way as to enhance people's normal cognitive and physicalfunctioning. Still another form of intervention in the development ofa human organism is the freezing of an embryo in liquid nitrogen to

Bioethics ISSN 0269-9702Volume 12 Number 3 1998

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postpone the birth of a person who subsequently will come intoexistence from that embryo. All of these interventions give usconsiderable control over how many people will exist, when peoplewill come into existence, and what sort of people there will be.

I shall explore the moral implications of these technologies andargue that we are morally required to intervene in the process ofbiological development of human organisms by testing and selectivelyterminating embryos with genetic defects that cause people to existwith severe disease and disability. As amatter of beneficence, we havea duty to prevent avoidable pain and suffering in the people we bringinto existence. As a matter of justice, we have a duty not to causepeople to exist with cognitive and physical disabilities that will limittheir opportunities for achieving a decent minimum level of lifetimewell-being. Each of these claims is motivated by the following moralasymmetry thesis: we do not have a moral duty to bring people intoexistence with good lives; but we do have a moral duty to prevent theexistence of people who would experience so much pain and sufferingas to make their lives not worth living for them on the whole.1Furthermore, in deciding whether to keep embryos frozen for longperiods of time, we have to consider the psychological impact onchildren born from these embryos after the deaths of their biologicalparents, or when their parents are at an advanced age. In addition, wemust consider whether we can justify keeping genetically defectiveembryos frozen until the time when inserting a missing gene orcorrecting a mutant gene become feasible practices.

MORAL ASYMMETRY ANDHARM

The moral asymmetry thesis that I articulated above rests on threenotions. The first is the person-affecting principle, which says that aperson is benefited or harmed when her interests in what happens toher are satisfied or defeated.2 Once a person exists, she has an interest

1 This thesis derives from JanNarveson's claim that we do not have amoral dutyto make happy people, but only tomake people happy. He argues that the benefit ofan act is the good it brings to already existing people and does not include the goodof people who come into existence as a result of the act. See Ùtilitarianism and NewGenerations', Mind 76 (1967), pp. 62^72, and `Moral Problems of Population',Monist 57 (1973), pp. 62^86. John Broome and Adam Morton discuss differentaspects of the moral asymmetry thesis in `The Value of A Person', Proceedings of theAristotelian Society, Supplementary Volume 68 (1994), pp. 167^98.

2 Here I follow the definition of harm given by Joel Feinberg in Harm to Others(New York, Oxford University Press, 1984), pp. 102^4, and Allen Buchanan andDan Brock in Deciding for Others: The Ethics of Surrogate Decision Making (New York,Cambridge University Press, 1989), pp. 162^9. Broome, ibid., Derek Parfit, Reasons

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in not experiencing pain and suffering and thus can be harmed if sheexperiences these over the course of her lifetime. The second notion isthe impersonal comparative principle, which says that, other thingsbeing equal, it is worse to cause a person to exist if it would be possibleto cause a different, better-off, person to exist instead.3 It involves acomparison, not between the existence and non-existence of oneperson, but rather between two distinct lives of two distinct people.On the impersonal comparative principle, we evaluate two potentiallives of two potential people who do not yet exist, while on the person-affecting principle we evaluate the life of one person who alreadyexists. Yet we can appeal to both principles to support the claim thatwe are morally required to prevent the existence of people with livesthat on balance are not worth living. That is, we prevent harm to theindividuals we cause to exist by fulfilling their interest in not having toexperience pain and suffering, and we avoid adding to the totalamount of suffering in the world.4 The third notion on which themoral asymmetry thesis rests is the metaphysical relation betweenembryos and persons.

`Person' is a psychological concept, while `human organism' is abiological concept. A human organism, in the form of a single-celledzygote, begins to exist at around the time of conception, when maleand female gametes fuse.5 Thereafter, the zygote develops into a

and Persons (Oxford, Clarendon Press, 1984), Part IV, and John Harris,Wonderwoman and Superman: The Ethics of Human Biotechnology (Oxford, OxfordUniversity Press, 1992), p. 89, define personal harm in comparative terms. That is,a person is harmedwhen she is madeworse off than shewould have been otherwise. Iavoid using the comparative sense of harm in considering whether being caused toexist with disabilities harms people, because these people would not exist withoutthe disabilities they have, and a coherent comparison can be made only betweentwo states of existence. The comparative sense of harm can be invoked only insofaras people exist and have interests. Otherwise, we should use an impersonal sense ofharm, comparing two distinct potential lives of two distinct potential people.

3 Parfit defends this principle in Reasons and Persons, Ch. 18, and `Comments',Ethics 96 (1986), pp. 858 ff., as does Jonathan Glover, `Future People, Disability,and Screening', in Peter Laslett and James Fishkin, eds. Justice Between Age Groupsand Generations (New Haven, Yale University Press, 1992), pp. 127^43.

4 This idea is discussed by Parfit, Reasons and Persons, and Harris, Wonderwomanand Superman, p. 90.

5 See Michael Lockwood, `When Does A Life Begin?', in Lockwood, ed.,MoralDilemmas in Modern Medicine (Oxford, Oxford University Press, 1985), pp. 9^31,Norman M. Ford, When Did I Begin? (Cambridge, Cambridge University Press,1988), pp. 97 ff., Stephen Buckle, Karen Dawson, and Peter Singer, `The SyngamyDebate: When Precisely Does A Human Life Begin?', in Singer et al., eds., EmbryoExperimentation (Cambridge, Cambridge University Press, 1990), Ch. 19, Harris,pp. 61^5, and Jeff McMahan, `The Metaphysics of Brain Death', Bioethics 9(1995), pp. 91^126.

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multi-celled embryo, a presentient fetus, a sentient fetus, and then thebody and brain of a person. The zygote, embryo, fetus, and person aredistinct but biologically related stages in the development of a humanorganism. Up to about 14 days after fertilization there is thepossibility of monozygotic twinning of the fused gametes. When itoccurs, twinning causes two genetically identical but numericallydistinct individual organisms to exist from the original zygote, andthese subsequently develop into two distinct persons with distinctpsychological properties. A person begins to exist when the fetal stageof the organism develops the structure and function of the brainnecessary to generate and support consciousness and mental life. Thisis when the fetus becomes sentient, at around 23^24 weeks ofgestation. Because the structure and function of the organism's brainwhich generate and support the psychological properties essential topersonhood develop gradually, persons come into existencegradually. The zygotic, embryonic, and presentient fetal stages ofthe organism are related to the person who develops from them tothe extent that they all have the same DNA in their cells and that thepsychological properties of the person causally depend on thebiological properties of the organism. But because a person's essentialpsychological properties are distinct from, and emerge later than, thebiological properties that define these other stages in the developmentof an organism, a person is neither identical with any one of thesestages nor with the organism itself.6 The embryo or presentient fetusis a potential person, not in the sense that it becomes a person, whichimplies numerical identity, but only in the sense that it has thepotential to develop the biological structures and functions necessaryto generate the consciousness and mental life constitutive ofpersonhood.7

6 McMahan draws a similar distinction between persons and human organismsin `The Metaphysics of Brain Death', as does Robert Elliot in Ìdentity and theEthics of Gene Therapy', Bioethics 7 (1993), pp. 27^40, and `Genetic Therapy,Person-Regarding Reasons and the Determination of Identity', Bioethics 11(1997), pp. 151^60. Compare these accounts with that of Ingmar Persson, whodraws a three-fold distinction between a conceptus, a human being, and a personin `Genetic Therapy, Identity and the Person-Regarding Reasons', Bioethics 9(1995), pp. 16^31. For a defense of the view that we are essentially human animals,see Eric Olson, The Human Animal: Personal Identity Without Psychology (Oxford,Clarendon Press, 1996), and `Was I Ever A Fetus?', Philosophy and PhenomenologicalResearch 57 (1997), pp. 43^59.

7 In Causing Death and Saving Lives (Harmondsworth, Penguin, 1977), Gloversays that a fetus is a potential person (p. 122), and Harris holds that embryos arepotential persons, or `pre-persons' (p. 58). Buckle subtly discusses the differencebetween the potential to become and the potential to produce in Àrguing fromPotential', Bioethics 2 (1988), pp. 227 ff. Reprinted in Singer et al., Ch. 9.

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The metaphysical distinction between human organisms andpersons has significant implications for the manipulation of genes inembryonic cells. The manipulation of one or more genes in these cellswould not disrupt the identity of the organism, provided that its basicstructure and function remained intact. Yet it would determine theidentity of a different person. For, as Robert Elliot has pointed out,even slight changes to the biological properties of an organism at thezygotic or embryonic stage would cause different psychologicalproperties to develop and thus select between which of a number ofdifferent people would come into existence.8 However, once anembryo has developed into a child with consciousness andmental life,genetic manipulation of its body's cells is more likely to be identity-preserving of personhood than identity-determining, since it alreadyhas developed a set of psychological properties. If this is correct, thenthe earlier genetic manipulation occurs in the development of ahuman organism, the more likely it is to determine that distinctpeople come into existence from it.

On the plausible assumptions that only beings with interests can beharmed by the defeat of those interests, that having interestspresupposes sentience, and that only late-stage fetuses and personsare sentient, it is morally permissible to terminate a human organismat an early stage of development. The termination affects no one whohas interests. One might object that having interests does notpresuppose sentience. For example, it may be said that future people,who do not yet exist and are not sentient, have an interest not to live ina polluted environment.9 But the core concept at issue here is harm,and harm consists in the defeat of particular interests of identifiablepersons who already exist and can experience the defeat of theseinterests. Terminating the development of a human organism at theembryonic stage does not kill a person but only prevents a person fromcoming into existence. There is no one who could be harmed becausethere is no identifiable individual with particular interests who existsat that time.

Similar reasoning underwrites the claims that we do not have amoral duty to bring people into existence, and that bringing someoneinto existence by itself does not benefit her, however good her life may

8 Elliot, Ìdentity and the Ethics of Gene therapy', and `Genetic Therapy,Person-Regarding Reasons and the Determination of Identity'. McMahanexplores the implications of the differences between genetic techniques that areidentity-determining and those that are identity-preserving in `CognitiveDisability, Misfortune, and Justice', Philosophy & Public Affairs 25 (1996), pp. 3^35.

9 Tom Regan first argued for this position in `Feinberg on What Sorts of BeingsCan Have Rights', Southern Journal of Philosophy 14 (1976), pp. 485^98.



be.We cannot say that being caused to exist is better for a person thanshe otherwise would have been, since otherwise she would not haveexisted. Put differently, there is no one who is caused to exist; rather,we make it the case that someone exists. Derek Parfit argues that therelation between existence and non-existence does not meet the `FullComparative Requirement', which says that we benefit someone onlyif we do what will be better for him.10 While causing someone to existmay be good for him, it cannot make him better off, since non-existence is morally neutral and therefore neither good nor bad. Wedo not have a moral duty to benefit persons by bringing them intoexistence, because we benefit persons by satisfying their interests, andit is difficult to see how non-existing persons could have an interest inbeing caused to exist.

However, while it is morally neutral to cause a person to exist witha life that on balance is good, it is morally wrong to bring a person intoexistence with a life that on balance is bad because of severe pain andsuffering. For in this case there is someone who actually experiencespain and suffering and who is harmed by being caused to exist in sucha condition. And since it is not morally neutral but wrong, we have amoral duty to prevent the existence of a personwhowould have such alife. Yet there is an air of paradox about the idea that, although we donot benefit people by bringing them into existence with lives that aregood on the whole, we harm people by causing them to exist withrestricted lives that are bad on the whole.11 Presumably, we harmsomeone by causing them to exist with a disability because we makethem worse off than they otherwise would have been. But if they didnot exist with the disability, then they would not have existed at all.Insofar as a person's life is worth living on the whole, being broughtinto existence with a cognitive or physical disability cannot be worsefor her, because if we terminated the development of the embryocontaining the gene that caused the disability, then she would not

10 Reasons and Persons, pp. 488^9.11 In `The Paradox of Future Individuals', Philosophy&Public Affairs 11 (1982),

pp. 93^112, Gregory Kavka defines a restricted life as òne that is significantlydeficient in one or more of the major respects that generally make human livesvaluable and worth living' (p. 105). Yet Kavka says further that `restricted livestypically will be worth living, on the whole, for those who live them' (p. 105).WhenI say that life is or is not worth living for a person, I mean it in the subjective ratherthan objective sense, or, what it is like for the person who lives it. McMahan offersinsightful discussions of this and related issues in `Cognitive Disability, Misfortune,and Justice', and `Wrongful Life: Paradoxes in the Morality of Causing People toExist', in Jules Coleman and ChristopherMorris, eds.,Rational Commitment and SocialJustice: Essays for Gregory Kavka (Cambridge, Cambridge University Press,forthcoming).

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exist. This is a variant of what Parfit has called the `Non-IdentityProblem'.12

Jonathan Glover has devised a strategy to sidestep the Non-Identity Problem. Instead of trying to draw a comparison betweenthe existence and non-existence of one identifiable individual, Glovermaintains that the relevant comparison is between two distinct lives oftwo distinct people. It is ìmpersonal' in the sense that `harm can bedone even though identifiable people are no worse off than theyotherwise would have been'.13 Glover uses the following example toillustrate the impersonal comparative principle. Imagine that afactory emits a chemical that causes babies to be born blind. On theNon-Identity Problem, they are not made worse off than theyotherwise would have been, since their lives are worth living andotherwise they would not have existed. But `what we should say hereis, not that the pollution made the blind children worse off than theywould have been otherwise, but instead that their condition is worsethan the condition of the other children who would have been born inthe absence of the pollution.'14 The choice is between bringingdifferent people into existence, while retaining the same number ofpeople who will exist.15 Both person-affecting and impersonal harmprinciples give us reasons to bring a normal child into existence ratherthan a diseased or disabled one. We prevent actual people fromexperiencing pain and suffering and thereby avoid defeating theirinterest in having healthy lives, and we avoid adding to the totalamount of suffering in the world.

In some genetically caused diseases, severe cognitive and physicaldisabilitymaymake people's lives so restricted that they are not worthliving. By definition, these lives fall outside the scope of the Non-Identity Problem. When we can predict that a disease would involve

12 Reasons and Persons, Ch. 16, and `Comments', pp. 854^62. Others who addressthis problem include McMahan, `Cognitive Disability' and `Wrongful Life',Kavka, `The Paradox of Future Individuals', JamesWoodward, `TheNon-IdentityProblem', Ethics 96 (1986), pp. 804^31, Matthew Hanser, `Harming FuturePeople', Philosophy & Public Affairs 19 (Winter 1990), pp. 47^70, and David Heyd,Genethics: Moral Issues in the Creation of People (Berkeley, University of CaliforniaPress, 1992), Chs. 4, 6. Robert Adams first articulated the Non-Identity Problemin Èxistence, Self-Interest, and the Problem of Evil',Nous 13, (1979), pp. 65^76.

13 `Future People, Disability, and Screening', p. 141.14 Ibid., p. 142.15 I assume that the same number of people will exist in the different outcomes.

This avoids complications involving different numbers of people and having todetermine which group is better or worse off than others. See Parfit's discussion of`Same People Choices', `Same Number Choices', and `Different Number Choices'in Reasons and Persons, pp. 356 ff. See also Hanser, `Harming Future People', andHeyd, Genethics.



so much disability, pain, and suffering as to make life not worth livingon the whole, we are morally required to prevent the existence ofpeople who would have the disease. Or, if we do cause people to existwith such a disease, then we are morally required to either cure themor alleviate the severity of their symptoms, insofar as we are able. Thefirst scenario that I described pertains to the impersonal sense of harmand potential persons, while the second pertains to the personal senseof harm and actual persons. One suggests genetic testing and selectivetermination of defective embryos as the appropriate strategy toprevent harm. The other suggests that the appropriate strategy toprevent or compensate for harmwould be gene therapy or some otherform of genetic alteration. A person is a further stage of developmentof the same human organism of which the embryo is an earlier stage.In this sense, embryos are potential persons, and failing to terminate agenetically defective embryo can cause harm by allowing it to developinto a diseased or disabled person.16 Because gene therapy is not yetfeasible for most diseases, genetic testing and selective termination ofgenetically defective embryos appears to be the only medicallyeffective and morally defensible way to prevent the sort of harm atissue. Before defending this claim, however, we should examine thedifferent forms of genetic intervention and assess their medical andmoral significance.

GENETIC INTERVENTION

There are three basic types of genetic alteration.17 Gene therapyconsists in the correction or addition of genes in the somatic (body)cells of a person to treat a disease the person already has, where theaim of treatment is to cure the disease or alleviate its symptoms. Bycontrast, genetic alteration of germ cells (gametes; sperm and egg) atthe zygotic or embryonic stage of the human organism prevents

16 Helga Kuhse and Peter Singer claim that `we can, of course, damage theembryo in such a way as to cause harm to the sentient being itwill become, if it lives,but if it never becomes a sentient being, the embryo has not been harmed'. SeeÌndividuals, Humans, and Persons: The Issue of Moral Status', in EmbryoExperimentation, p. 82. Furthermore, Harris maintains that `harm done at the pre-person (embryo) stage will be harm done to the actual person she becomes. It is aform of delayed-action wrongdoing'. Wonderwoman and Superman, p. 153. I believethat persons can be harmed or wronged by what we do or fail to do to embryos evenif embryos do not strictly speaking become persons.

17 Patricia Baird provides an excellent overview of these issues in ÀlteringHuman Genes: Social, Ethical, and Legal Implications', Perspectives in Biology andMedicine 37 (1994), pp. 566^75. See also Leroy Walters and Julie Gage Palmer,The Ethics of Human Gene Therapy (New York, Oxford University Press, 1997).

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diseased persons from coming into existence. It is therefore mistakento call this form of genetic manipulation `therapy,' because when thegametes are altered, there are no existing persons who might benefitfrom this act.18 `Therapy' implies that there is a disease to be treatedor cured, and it is not zygotes or embryos but rather persons or late-term fetuses who are diseased. Defective genes in embryonic cells maybe the causes of diseases, but the diseases do not manifest themselvesuntil the organism has developed into a fetus or person. Unlikesomatic-cell gene therapy, which preserves the identity of alreadyexisting persons who are treated, germ-line genetic alterationdetermines the identity of the person who would come into existencefrom the embryo in which a defective gene is corrected or replaced bya normal one. The intervention takes place before the process of celldifferentiation and the development of tissues and bodily organs hasbegun, and thus determines that a biologically and psychologicallydistinct individual will come into existence from the one who wouldhave come into existence from the same embryo had the defectivegene not been corrected or replaced. Genetic enhancement involvesnon-therapeutic alteration of genes aimed at improving cognitiveand physical functioning which already are at or above the normallevel for persons.

The three types of genetic alterationwhich I havementioned are tobe distinguished further from selective termination of embryos aftergenetic testing has revealed the presence of disease-causing genes, ormarkers for these genes, in the cells of embryos.19 Like germ-linegenetic alteration, germ-line genetic testing and termination is not atherapeutic but a preventive strategy designed to avoid the existenceof individuals who would be severely disabled and have restrictedlives. Let us now further explore the four types of genetic interventionat the embryonic stage of development of a human organism.

18 Elliot and Persson fail to recognize this in their respective uses of `genetherapy'.

19 The diseases I discuss involve genetic defects in the nuclei of cells. Genes in themitochondria of cells can mutate in the same way that the more familiar nucleargenes do. And like nuclear genes, mutations in mitochondrial genes may lead todisease. There are indications that familial Alzheimer disease may be caused by afaulty mitochondrial gene, though the research has not yet yielded any definitiveconclusions. Moreover, my concern is with genetic testing rather than geneticscreening. `Genetic testing denotes the use of specific assays to determine the geneticstatus of individuals already suspected to be at high risk for a particular inheritedcondition because of family history of clinical symptoms; genetic screening involvesthe use of various genetic tests to evaluate populations or groups of individualsindependent of a family history of a disorder.' ArnoMotulsky et al., Assessing GeneticRisks: Implications for Health and Social Policy (Washington, D. C., National AcademyPress, 1994), p. 4.



Somatic-cell gene therapy is not yet feasible for treating themajority of genetically caused diseases. This is because gene therapyis primarily relevant to single-gene disorders, and chromosomaldisorders such as Down syndrome involve large segments of DNAwhich are not amenable to treatment. Moreover, the single-genedisorders that might be amenable to gene therapy are recessive ratherthan dominant disorders. Recessive disorders, where a single copy ofthe normal gene is sufficient for one to function within the normalcognitive and physical range for persons, may be treatable becauseinserting one copy of a normal gene into someone with a double doseof the defective gene may be enough to raise that individual'sfunctioning or health up to the normal range. Dominant disorders,by contrast, result even when the affected person has only a singlecopy of the defective gene. These disorders might be prevented orcured by correcting themutationwithin the gene. Presently, however,it is not possible to correct a mutation but only to insert an additionalnormal copy of a gene into cells, and therefore only recessive disorderscan be treated through genetic intervention.

In theory, a recessive disorder like cystic fibrosis (CF) could betreated by inserting a normal gene into the relevant cells so that thepancreas produced the necessary enzymes for food absorption, as wellas to ensure proper function of the glands in the lining of the bronchialtubes. Similarly, in hemophiliacs, who are unable to produce normalamounts of a factor necessary for blood clotting, the missing gene couldbe delivered through injections. In practice, though, what has plaguedthe efforts of gene therapy to curepeople of diseases, or at least effectivelytreat their symptoms, is the lackof suitable vectors todeliver therapeuticgenes into human cells and maintain them in working order. Viralvectors have been the method used to date, specifically adenovirusesand retroviruses, which slice copies of their genes permanently into thechromosomes of the cells they enter. Yet this method has been largelyunsuccessful because the stripped-down viruses that have been used donot provide a stable platform for the genes to operate efficiently. Someofthese viruses are not large enough to carry a full human gene and itsswitches, while others may provoke an adverse response by the immunesystem. Work on hemophiliacs, children with severe combinedimmunodeficiency disease (SCID), and familial hypercholesterolemiahas shown some promise. But for the majority of genetically baseddiseases, gene therapy is not yet an effective cure or treatment.20

20 But see R. M. Blaese et al., `Treatment of Severe Combined Immuno-deficiency (SCID) Due to Adenosine Deaminase Deficiency with CD34+ SelectedAutologous Blood Cells Transduced with a Human ADA Gene', Human GeneTherapy 4 (1993), pp. 521^7, M. Grossman et al., `Successful Ex Vivo Gene Therapy

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Germ-line genetic alteration initially may seem more attractivethan gene therapy. Manipulation or replacement of geneticabnormalities in germ cells at the zygotic or embryonic stage after invitro fertilization (IVF) would correct a defect before it could manifestitself as a disease in an existing person. This type of alteration wouldaffect the resulting cells in the process of differentiation and in turn thegerm line of the person who develops from the embryo. The alteredgenes would then be passed on to future generations of the person'soffspring. But it is questionable whether germ-line geneticmanipulation would be desirable from an evolutionary perspective.Some degree of genetic mutation is necessary for species to adapt tochanging environmental circumstances, and some genetic disordersconfer benefits on certain populations. For example, the gene forsickle-cell anemia provides greater resistance to malaria. Altering agene or genes at the germ line to correct one disorder may only leadto other disorders. This also raises the question of whether we have aduty to prevent passing on unforeseeable consequences of germ-linealteration to future generations, which is morally significant for tworeasons. First, people existing in the futuremight be adversely affectedby a policy to which they did not consent. Second, it would beextremely difficult to determine whether the benefits of such a policywould outweigh its harms, in which case it may be morally preferableto err on the side of caution and prevent such a policy from beingimplemented. In sum, there may be both medical and moral reasonsagainst germ-line genetic alteration.

Genetic enhancement is a non-therapeutic form of geneticintervention which aims to raise cognitive and physical capacitiesabove the normal range of functioning for persons. But to the extentthat people's actual cognitive and physical functioning enable them toachieve a decentminimum level ofwell-being, there are no compellingmedical or moral reasons for genetic enhancement. Indeed, somewould say that there are compelling reasons for prohibiting it. Insofaras genetic enhancement aimed at something over and above diseaseprevention and health promotion, it would threaten to introduce aprogram of positive eugenics which would unjustly discriminateagainst certain groups of people who are moderately disabled andwhose lives, though somewhat restricted, are nonetheless worth living.Iwill return to the eugenics question in the last part of the next section.

Directed to Liver in a Patient with FamilialHypercholesterolemia',NatureGenetics 6(1994), pp. 335^41, R. C. Boucher et al., `GeneTherapy for Cystic Fibrosis Using E1Deleted Adenovirus: A Trial in the Nasal Cavity',HumanGene Therapy 5 (1994), pp.615^39, and Melissa A. Rosenfeld, `Human Artificial Chromosomes Get Real',Nature Genetics 15 (1997), pp. 333^5.



My analysis of the different forms of genetic alteration and theproblem of their feasibility supports my earlier claim that genetictesting and selective termination of embryos with defective genes thatcause people to exist with severe pain and suffering is the onlymedically effective and morally defensible way to prevent this stateof affairs from obtaining. It will be instructive to cite some specificdiseases that recommend such a preventive measure.

WHICH LIVES SHOULD BE PREVENTED?

Present biotechnology allows us to test embryonic cells for geneticabnormalities that lead directly to severe early-onset disorders, likeTay-Sachs disease, Hurler syndrome, Lesch-Nyhan syndrome, andCanavan's disease, as well as late-onset disorders like Huntington'sdisease.21 We also can test embryos for genes that predispose people tochronic and ultimately fatal conditions like coronary heart disease andcancer. Genetic mutations play a causal role in many diseases byaltering a crucial enzyme or other protein. The alteration may occurin differing degrees, depending on the extent of interaction betweengenes and the environment. In the specific diseases I mentioned above,though, environment plays little or no causal role in their occurrence.Either the defective gene necessarily causes the disease, or else it has avery high probability of causing it (95%with theHuntington's gene).

In Tay-Sachs, for instance, babies appear quite normal at birth.But in the first year of life their nervous systems degenerate, and theyusually die by the time they reach 3 or 4. This disease is caused by thepresence of two copies of an abnormal gene, or mutant allele, at aparticular site on one of the 23 chromosome pairs. Tay-Sachs is anautosomal recessive disorder, which effectively means that the childinherits one mutant allele from each parent. Through the fusion ofthe gametes in the zygote that develops into the embryo, fetus, andperson, the parents transmit the disease to their child.

Ideally, we would use gene therapy by inserting an additionalnormal copy of the defective gene into the relevant cells and thus curethe disease. But Tay-Sachs, like most recessive (and dominant)disorders, has not proven amenable to therapy. Alternatively, wecan test and selectively terminate embryos with genes that cause this

21 Canavan's is a degenerative disease that strikes infants, leading to the decayof the nervous system and early death. Hurler syndrome involves disruption ofcognitive development in early childhood and usually death by age 10. Lesch-Nyhan syndrome causes both mental retardation and compulsive self-mutilationin boys. Philip Kitcher offers an insightful discussion of the genetic causes of theseand other diseases in The Lives to Come: The Genetic Revolution and Human Possibilities(New York, Simon and Schuster, 1996).

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or other severely disabling diseases, preventing these diseases bypreventing the existence of the people who would have them. Thispractice can be justified on two grounds. Beneficence requires thatwe not harm people by causing them to experience pain and sufferingover the balance of their lives. In addition, justice requires that we notdeny severely disabled people the same opportunities for achieving agood life as are open to others who are healthy or have only moderatecognitive or physical disabilities.22 Arguably, the justice requirementwill apply to only a small number of people, since the idea of equalopportunity for a good life implies a certain number of years toundertake and complete projects for a decent minimum level of well-being, and most people with severe early-onset genetically causeddiseases have relatively short lifespans. Perhaps this is not the casewith a disease like CF, where people afflicted often live for 30 yearsor more. But I do not believe that this genetically caused disease is soseverely disabling and painful that we can justifiably prevent the livesof the persons whowould have it. Considerations of justicematter; butwhat matters more than ensuring equal opportunity for achieving agood life is preventing avoidable severe pain and suffering that peopleactually experience once they exist. These are what make lives notworth living on the whole. Indeed, it is often the severe pain andsuffering associated with disabilities which preclude people fromhaving the opportunities to achieve a decent minimum level oflifetime well-being.

Testing of embryonic cells for genetic abnormalities may be doneby extracting cells from preimplantation IVF embryos. To produceextracorporeal IVF embryos for this type of testing, fertility drugssuch as Clomid or Pergonal can be given to a woman to inducesuperovulation and in turn produce a number of eggs that can berecovered for fertilization with sperm. One advantage of producingmultiple embryos is that, if genetic abnormalities are detected in anyone of the embryos, then it can be selectively terminated and another,normal, embryo can be implanted in the woman's uterus. This wouldenable parents to have a normal child instead of a disabled one and toavoid any burdens that such a child might have on them or, if theyhave other children, the rest of the family. Significantly, the capacityto produce multiple IVF embryos is largely what grounds theimpersonal harm principle, since at least two embryos must be

22 See Glover, `Future People, Disability, and Screening', McMahan,`Cognitive Disability', and Allen Buchanan, Èqual Opportunity and GeneticIntervention', Social Philosophy and Policy 12 (1995), pp. 105^35, and `ChoosingWho Will Be Disabled: Genetic Intervention and the Morality of Inclusion', SocialPhilosophy and Policy 13 (1996), pp. 18^46.



available for a parent or parents to choose to bring a normal child intoexistence instead of a disabled one.

Another attractive feature of this method, as Robert Edwardsexplains, is that ìdentifying embryos with genetic abnormalitieswould offer an alternative to amniocentesis during the secondtrimester of pregnancy, and the àbortion' in vitro of a defectivepreimplantation embryo . . . would be infinitely preferable to abortionin vivo at twenty weeks of pregnancy or thereabouts as the results ofamniocentesis are obtained'.23 Testing preimplantation IVF embryosfor genetic abnormalities would be preferable to testing fetal cells forthese abnormalities by amniocentesis or chorionic villus samplingbecause, unlike these invasive procedures, it would not be painful tothe pregnant woman and would avoid certain medical risks.Specifically, putting a needle into the uterus to extract cells fromeither the amniotic fluid or embryonic membrane triggers amiscarriage once in every 50 to 100 pregnancies. Moreover, villussampling may cause limb deformities in the fetus.

Terminating the development of one embryo and implanting adifferent embryo would mean that the life of one potential person wasnot allowed to become actual and that the life of a different potentialpersonbecameactual instead.The samenumberof peoplewouldexist,but they would be different people. Yet whether one or a differentpotential person is allowed to exist does not matter morally. Rather,what matters morally is preventing avoidable pain and suffering thatactualpeoplewill have toexperience.Andto theextent thatanembryocontaining a disease-causing gene will result in severe pain andsuffering in the person who develops from it, we are morally requiredto prevent the disease, pain, and suffering by terminating thedevelopment of that embryo. What must be emphasized, however, isthat themoral requirement to terminate embryos and therebypreventcertainpeople fromcoming into existencepertains only to those peoplewhowouldhave severe, not justmoderately severe,diseases.Only severediseasesmake people's lives notworth living on thewhole.

One consequence of not preventing genetically defective embryosfrom resulting in severely diseased or disabled persons is that a childcaused to exist in such a condition could file a tort of wrongful lifeagainst his parents.24 Or, if the child is cognitively or physicallyunable to do so, a different person could file a tort on the child's behalf.

23 R. G. Edwards and J. Purdy, Human Conception In Vitro (London, AcademicPress, 1981), p. 373.

24 See Feinberg, `Wrongful Life and the Counterfactual Element in Harming',in Freedom and Fulfillment (Princeton, Princeton University Press, 1992), pp. 3^36,Heyd, Genethics, Ch. 1, Harris, Wonderwoman and Superman, Ch. 4, and McMahan,`Cognitive Disability' and `Wrongful Life'.

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Suppose that a boy has Duchenne muscular dystrophy, a recessivedisorder traceable to a genetic defect on the X chromosome whichadversely affects the dystrophin protein. This defect causes musclesto begin weakening at age 3 and subsequent respiratory failure, whichgives children afflicted with the disease an average life expectancy of16^20 years. If the boy's mother knew that she was a carrier of thedefect and that there was a 50% chance of transmitting it to her son,was able to abort the embryo containing the defect, yet allowed thechild to be born from that embryo, then the boy could claim that hisparents acted in reckless disregard of his welfare, wronged andharmed him, and accordingly owe him compensation for causinghim to exist with a condition that defeats his right and interest inhaving a life that is not severely restricted. The person-affectingprinciple would ground the child's claim against his parents.

There would not be grounds for a tort of wrongful life, however, ifthe child claimed that genetic intervention other than testing andtermination at the embryonic stage of development, such as adding anormal copy of the dystrophin gene, would have made a significantdifference between the quality of life he actually experiences andwhathe might have experienced otherwise. For at the time of theintervention, there would not have been any identifiable individualto be benefited or harmed. Genetic alteration at such an early stageof development of the organism would have resulted in a completelydifferent set of biological and psychological properties that wouldhave belonged to a different person. So the child only could claim thatthe wrong or harm was committed by not terminating the defectiveembryo fromwhich he developed, not by failing to add a normal copyof the gene. Gene therapy involving somatic cells at an early age afterbirth also would entail different subsequent biological andpsychological properties as the child's life unfolded. Arguably,however, these would not be so radically different from the propertiespossessed before the therapy that they would be of a different person,since presumably the child who receives the therapy already has afairly developed biological and psychological life. Although some ofhis properties would have changed, intuitively there would be enoughbiological and psychological continuity before and after the therapyto say that the child cured of CF or SCID by gene therapy wouldremain the same individual. If such a child's parents had access toaffordable gene therapy that could cure his disease or treat thesymptoms associated with it, but failed to seek such treatment, thenperhaps the child could claim that his parents harmed or wrongedhim by defeating his interest in being cured of or treated for a diseasethat was amenable to gene therapy. But to the extent that the childalready exists with a condition for which his parents are not



completely responsible, strictly speaking this case would involvesomething other than the standard notion of wrongful life.

Thecases that Ihave just discussed involvephysical disability.Moredifficult to assess would be gene therapy to correct severe cognitivedisability at a fairly early stage of a person's life. This could have asignificant effect on subsequent psychological properties that arguablywould be those of a different person from the one who underwentcognitive gene therapy for the affected brain cells at an earlier time,giventhat thebraingeneratesandsupports theconsciousnessandotherpsychological properties necessary for personhood and personalidentity through time. The medical prospects for cognitive genetherapyareeven lesspromising thantheyare forphysicalgene therapy,and the moral implications of such therapy are so complex that Icannot address them adequately here. Nevertheless, cognitive andphysical disability may very well have different relative weights indetermining personal identity through time, as well as in determiningwhether or towhat extent people can be harmed.

I have claimed that the diseases that morally require us to preventthe existence of people who would have them must be so severelydisabling that they make their lives not worth living on the whole.This is not the case with moderately severe genetic disorders likeDown syndrome, where, although there is some cognitive andphysical impairment, the lives of people with this disorder can befulfilling and thus verymuchworth living. So therewould be nomoralgrounds for preventing the existence of people with Down syndrome.But there would be nomoral requirement to bring them into existenceeither, given that existence is morally neutral and entails norequirement to cause people to exist with good lives.

A further distinction must be drawn between early-onset geneticdisorders of the sort I have been discussing, which affect people frombirth or early childhood, and late-onset genetic disorders, likeHuntington's disease, which do not affect people until the adult stageof their lives. The onset of symptoms in people afflicted withHuntington's may range anywhere from age 30 to 50, and theseinclude progressive loss of muscle control and dementia. Generally,they die within 15 years after onset. Prior to this time, they usuallyhave normal lives with comparatively high levels of cognitive andphysical functioning for a considerable number of years. In trying todetermine whether people's lives are worth living on the whole, weshould do so by evaluating the quality of their lives in terms of all thestages of their lives. But the radical difference in cognitive andphysical functioning before and after the onset of symptoms in diseaseslike Huntington's makes it difficult to assess overall quality of life forthe people who have them.

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With severe adult-onset diseases, perhaps themost plausible way tomeasure lifetime quality is to weigh the level of normal functioningper year lived against the level of disability per year lived and arriveat an average level of well-being for the person's entire lifespan.25 Onthis view, the earlier the onset of symptoms in the person's life, thelonger the period of time between onset and death, and the moresevere the disability, pain, and suffering associated with the disease,the stronger the reason will be for saying that the person's life is notworth living on the whole. Correspondingly, there will be a strongerreason for preventing that life by terminating the embryo with thegene that causes the disease. Thus, for a person afflicted with thedegenerative physical and cognitive symptoms of Huntington'sdisease at age 30, the severity of the pain and suffering he experiencesin his last 15 years may be bad enough to outweigh the normalfunctioning he had in his first 30 years and average out to a level oflifetime well-being which falls below the decent minimum. This inturn may lead us to conclude that his life is not worth living on thewhole for him and that, if we could have foreseen this through genetictesting of the embryo from which he developed, then we should haveterminated the embryo and thereby prevented him from existing.

Or consider a more controversial variant of the same case. Supposethat genetic testing could predict that symptoms would not manifestthemselves until age 50. One might claim that the pain and sufferingcaused by the disease in the last 10 or 15 years of the person's lifewould be so severe as to outweigh the good 50 years and thus makethe person's average lifetime well-being fall below the decentminimum. Although it would be difficult to sustain, here too theremay be a principled reason for terminating an embryo with theHuntington's gene. It may weigh the decision in favor of preventingthe existence of a person who would have the disease over causing himto exist with a life that has a wretched last stage. Alternatively, onecould take the view that, with adult-onset diseases, it is the victim'sresponsibility to decide whether to go on living beyond a certainpoint. This is consistent with the conviction that the value of a life isdetermined subjectively by the person whose life it is. But whether thisview were to figure in any way in public policy would depend, amongother things, on the legal climate in which the afflicted person wasliving.26

25 Thomas Hurka presents a model that measures quality of life in terms ofaveraging achievements in earlier and later stages of life in Perfectionism (New York,Oxford University Press, 1993), pp. 70 ff. See also Brock, `Quality of Life Measuresin Health Care and Medical Ethics', in Life and Death: Philosophical Essays inBiomedical Ethics (New York, Cambridge University Press, 1993), pp. 268^324.

26 I thank a referee for Bioethics for raising this issue.



Pain and suffering in the last stage or years of a person's life mustbe weighed against the achievements afforded by normal cognitiveand physical functioning in earlier stages. Fifty years of normalfunctioning should be enough for a person to complete many of theprojects in his life plan and make for a life that is worth living. If so,then the fact that a person loses his normal functioning at age 50 byitself is not enough to support the claim that on balance his life is notworth living and that he should not have been allowed to come intoexistence. Indeed, some people have lives of thirty years that are fullof achievements. A shorter life can be very well worth living. But ifthe pain and suffering in one's last years are severe enough, and if thenumber of these years is large enough, then this may weigh thedecision in favor of preventing the person from coming intoexistence. The experience of severe pain and suffering, more so thanwhat it implies about limited opportunities for achievement, groundsthe claims that a person's life on balance is not worth living for himand that it is morally wrong to cause a person to exist with such alife.

Two objections might be raised against the claim that people withsevere disease or disability should not be brought into existence.Disabilities rights advocatesmight argue that intervention in the formof testing and selectively terminating genetically defective embryoswould reduce the number of people with disabilities. Consequently,public support for persons who already have disabilities would erode.It would lead to a devaluation of the lives of the disabled and todiscrimination against them. To rebut this objection, we can appealto Allen Buchanan's point that ìt is not the people with disabilitieswhich we devalue, it is the disabilities'.27 Buchanan further says `wedevalue disabilities because we value the opportunities and welfareof the people who have them ^ and it is because we value people, allpeople, that we care about limitations on their welfare andopportunities. We also know that disabilities, as such, diminishopportunities andwelfare, evenwhen they are not so severe that the livesof those who have them are not worth living'.28 The underlyingrationale for this position is that it is a matter of justice, not onlybeneficence, that we remove or prevent limitations on an individual'sopportunities for a decent life. But the second passage cited fromBuchanan leaves open the possibility that it is morally permissible toterminate embryos with genetic defects that would lead to peoplehaving lives with limited opportunities that are nonetheless worthliving. Against Buchanan, I believe that we should terminate only

27 `Choosing WhoWill Be Disabled', p. 32. Emphasis added.28 Ibid., p. 33.

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those embryos with genetic defects that manifest themselves in severedisabilities that make life on balance not worth living.

Still, we have to weigh the relative importance of cognitive andphysical functioning for different people in assessing quality of life.Suppose it were discovered that the adult-onset motor neuron diseaseamyelotrophic lateral sclerosis (ALS) had a genetic cause and that thedisease could be prevented only by terminating embryos whose cellscontained the defective gene. The case of the brilliant theoreticalphysicist Stephen Hawking illustrates that a person can suffer from asevere physical disability as a symptom of ALS for well over thebalance of his life yet maintain a high level of cognitive functioningwhich makes life for him very much worth living. It would be difficultto adduce reasons for preventing such a life from coming intoexistence, despite the fact that ALS is a severely disabling disease.On the other hand, for people who value physical functioning veryhighly (e.g. athletes, dancers), severe physical disability may leadthem to judge that on balance their lives are not worth living, even iftheir normal cognitive functioning remains intact. Granted, peoplecan adapt their preferences and life plans to adult-onset disabilitiesand the limited opportunities they entail. But it is not so easy to do thisif one has to endure constant pain and suffering over a considerableperiod of time. Furthermore, in the case of someone like Hawking, ifthe pain associated with the physical disability were so severe that itadversely affected his cognitive functioning, then we might considerwhether he would believe that his well-being was at a level highenough for him to judge that his life was worth living.

A second objection to my view is that any form of geneticintervention is motivated by the desire to improve the human speciesthrough selection. This amounts to a program of positive eugenics,which would lead to a repeat of the inhumane treatment of peopleand a violation of their intrinsic worth which have occurred in recenthistory.29 To this objection, we can respond by saying that the aim ofany medically and morally defensible form of genetic interventionshould not be to enhance people's genotype or phenotypic traits, butonly to ensure that the people we do cause to exist have normal, orclose to normal, cognitive and physical functioning over the balanceof their lives. In preventing the existence of people with severedisability, we are not aiming to enhance or improve lives that alreadyare, or would be, at a decent minimum level of well-being, but only toensure that the people we do bring into existence will not fall well

29 See, for example, Daniel Kevles, In the Name of Eugenics: Genetics and the Uses ofHumanHeredity (NewYork, Alfred A.Knopf, 1985), an examination of the history ofeugenics in the United States.



below this level. This accords with the moral asymmetry thesis. Wehave no moral duty to bring people into existence with good lives.But if we do bring people into existence, we have a moral duty toensure that their lives do not contain so much pain and suffering as tobe not worth living for them on the whole.

The negative eugenics I am defending has affinities with whatPhilip Kitcher calls ùtopian eugenics'.30 This involves a policyguaranteeing that people have reproductive freedom in choosingwhich embryos they allow to develop and subsequently the peoplethey bring into existence. Their choices must be free of any sociallycoercive pressure to prevent people from existing for economic rea-sons or perfectionist ideals. Provided that genetic testing andselective termination of defective embryos are practiced in order toprevent extreme pain and suffering in people, not to enhance theircognitive and physical capacities above the normal range, and thatreproductive technologies like IVF and genetic testing areaffordable and accessible to all, utopian eugenics is a morally jus-tifiable policy.

LONG-TERMCRYOPRESERVATION

Another practice made possible by reproductive biotechnology isthe storing of frozen embryos in èmbryo banks' of liquid nitrogen.One attractive feature of this type of cryopreservation is that awoman could decide to preserve an embryo produced by IVF fromher egg and a man's sperm in such a bank in order to pursue acareer and later have the embryo implanted in her uterus forpregnancy and birth. Assuming that long-term storage does notentail a risk of genetic mutation in embryonic cells, she couldundertake a later pregnancy without fear of birth defects regardlessof her age because the embryo fertilized at the earlier time would bebiologically optimal. Moreover, if genetic testing determines that anembryo has a genetic abnormality that likely will result in aseverely diseased or disabled person, then storing multiple IVFembryos gives parents the choice to terminate the defective embryoand implant a normal one instead. In addition, cryopreservation ofembryos for an extended period of time may make any geneticmutations they contain correctable by the insertion of normal copies

30 The Lives to Come, p. 202. See also Glover, What Sort of People Should There Be?(Harmondsworth, Penguin, 1984), John A. Wagner, `Gene Therapy Is notEugenics',Nature Genetics 15 (1997), p. 234, and Buchanan, Brock, Norman Danielsand Daniel Wikler, In the Shadow of Eugenics: the Human Genome Project and the Limits ofEthical Theory (forthcoming).

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of the relevant genes, if such a technique becomes feasible in thenear future. This would determine the identity of the personbrought into existence free from disease, who would replace thediseased individual who would have existed instead from the sameembryo without the altered or additional gene. But it is worthrepeating that it is not whether genetic alteration or therapy isidentity-determining or identity-preserving which is morallysignificant, but rather the sort of experience the persons who arebrought into existence will have.

There are reasons to be wary of freezing and storing embryos forlong periods of time, however. It is unknown whether this processmight entail genetic mutations in embryonic cells which mightresult in disease and premature death in the individuals who comeinto existence in this way. Also, IVF and cryopreservation ofembryos make it possible for a person resulting from such anembryo to have three distinct mothers: (1) the genetic, or biologicalmother, whose gamete contributes 23 chromosomes to the embryoand determines many of the subsequent biological and psycho-logical properties of the child who develops from the embryo; (2)the gestational mother, in whose uterus the embryo is implantedand who gives birth to the child; and (3) the social mother whoraises and cares for the child. The social mother is perhaps the mostimportant of the three with respect to the child's interests, since sheis the one who cares for the child when it has the requisitepsychological properties for interests, rights, and a biographical self.To the extent that only individuals with interests and rights can beharmed, and these interests and rights can be affected directly bythe social mother, she can directly affect the welfare of the child.But the relationship between a child and its biological parents canhave a significant psychological impact on the child as well.

If an embryo is frozen and not implanted until many years afterfertilization, then it is possible for a child to be born from that embryoand come into existence after the deaths of its biological parents. Evenassuming that there are no known genetic abnormalities in theembryo, the prospect of being born after the deaths of its biologicalparentsmay have harmful effects on the child's psychological identity,its sense of self. A mature self ordinarily will have a relationship withits biological parents which involves more than mere knowledge ofwho they are. There may be an even greater sense of harm to a childresulting from an embryo stored for a considerable period of time.Earlier, I said that storing embryos could allow a woman to pursue aprofessional career before having a child. But suppose that a woman'segg, fertilized when she was 30, is frozen and not implanted in her stillnormally functioning uterus (or that of a surrogate mother) until she



is 60.31 She becomes pregnant and decides to bring the pregnancy toterm. The increasing likelihood of disease with agemaymean that thechild or adolescent born from this pregnancy would have the burdenof caring for her mother or both parents before she was emotionallymature enough to do so. It also would be an obstacle to her ownemotional development as a person and thus have a deleterious effecton her overall well-being. With these issues in mind, it will beinstructive to consider a well-known legal case in the United Statesinvolving frozen embryos.

In December 1988, seven embryos produced in vitro from thegametes of Mary Sue Davis and Junior Lewis Davis were placed incryogenic storage for possible future implantation.32 In February1989, the couple filed for divorce, at which time the question arose asto whether the right of Mrs. Davis (then remarried as Mrs. Stowe) tobecome amother outweighedMr.Davis' right not to become a father.Arguing inMr.Davis' favor, JohnRobertson concluded that the rightto avoid biological offspring should have priority over the right toreproduce using frozen embryos.33 While Robertson's argument ispersuasive as far as it goes, it pays insufficient attention to the interestsof the future children who may be produced from these embryos.More specifically, it does not adequately consider how long-termcryopreservation of embryos may adversely affect the well-being ofchildren born from embryos implanted in surrogate mothers afterthe deaths of their biological parents, or if children are born whentheir biological parents are at an advanced age.

These points underscore some of the disturbing implications ofwhat amounts to altering the normal lifespan of a human organismand the normal reproductive cycle. In particular, it forces us to askwhether we have a moral obligation to impose some time limit afterwhich frozen embryos should not be implanted. Indeed, the HumanFertilization and Embryo Act of 1991 in the United Kingdomstipulated a five-year limit on the storage of frozen embryos, afterwhich time they were to be destroyed. Even if time limits on storageresolve the problems involving the length of a biological lifespan and

31 Eight years ago, in `Contemporary and Future Possibilities for HumanEmbryonic Manipulation', Mark Ferguson wrote ìt is unclear how well theageing human female reproductive system would cope with such good em-bryos'. In Anthony Dyson and John Harris, eds., Experiments on Embryos(London, Routledge and Kegan Paul, 1990), p. 10. Yet recently a woman of63 in Los Angeles gave birth to a healthy baby girl. See Gina Kolata, ÀRecord and Big Questions as Woman Gives Birth at 63'. New York Times, April24, 1997.

32 Davis v. Davis 1989 WL 140495 (Tenn Cir 1984) rev'd 842 S. W. 2D 588, 597(Tenn 1992).

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the reproductive cycle, the question remains as to whether disposingof embryos is morally permissible.

Bonnie Steinbock maintains that it matters whether we think thatembryos should be preserved because of their symbolic value orbecause they have a right to life. The import of this question derivesfrom a distinction she draws between moral status and moral value.34

Moral status is limited to beings with interests of their own, that is,sentient, aware, beings. Moral value concerns the symbolic value ofentities, even if they lack moral status. The debate in the UnitedKingdom may be taken either from the point of view of moral statusor from that of moral value. If, as the Church maintains, embryoshave moral status and rights, then it is impermissible to deliberatelydestroy them. But if they lack moral status, then we still can discusswhether respecting them as symbols of human life is consistent withdestroying them.35 By Steinbock's lights, destroying embryos is asrespectful of human life as is keeping them frozen for long periods,and this understanding of moral value seems plausible.

Nevertheless, the possibility that deletion of defective genes andinsertion of normal genes in embryonic cells will become feasible inthe near future may provide a reason for keeping embryos in frozenstorage. This would be the case if parents wanted to have a normalchild at some point not too late in their lives and were able to produceonly one viable but genetically abnormal embryo from their gametes.Yet if they were able to produce multiple embryos and none of themwas genetically abnormal, then, given that there is no moralobligation to bring people into existence, there would be nocorresponding moral obligation to preserve any of these embryos onthe basis of their presumed moral status.

CONCLUSION

I have examined two aspects of reproductive biotechnology ^genetic testing and selective termination of defective embryos, andlong-term cryopreservation of embryos ^ and have explored theethical implications of each. In the first case, I have argued thatwe are morally required to terminate the development of embryoswith genetic defects that cause severe disease or disability in people

33 `Resolving Disputes over Frozen Embryos', Hastings Center Report 19(November-December 1989), p. 11. More recently, Robertson examines this andrelated issues in Children of Choice: Freedom and the New Reproductive Technologies(Princeton, Princeton University Press, 1996).

34 Life Before Birth: The Moral and Legal Status of Embryos and Fetuses (New York,Oxford University Press, 1992), pp. 5^41.

35 I thank Bonnie Steinbock for pointing this out.



who develop from them. The moral justification for this view is thatit is wrong to cause people to exist when the avoidable pain andsuffering they experience make their lives not worth living on thewhole. This claim is motivated by both the person-affecting andimpersonal harm principles. If we cause these people to exist withsevere disease and disability, then we defeat their interest in livingwithout pain and suffering. Or, if we are considering whether tocause people to exist, then it is better, other things being equal, toprevent the existence of a person with severe cognitive and physicaldisability and instead bring into existence a person with normalcognitive and physical functioning. By doing so, we avoidgratuitously adding to the total amount of suffering in the world.In addition, considerations of justice support this position, becauseit means that people will not come into existence with a conditionthat will severely limit their opportunities for achieving a decentminimum level of lifetime well-being. Consistent with the idea ofnegative eugenics, we should prevent the existence of people whowould have severe disease and disability, not in order to raise theaverage level of people's cognitive and physical functioning, butrather to prevent the pain and suffering that make people's livesnot worth living on the whole. The aim of negative eugenics isdisease prevention and health promotion, not enhancement ofnormal capacities.

With respect to long-term cryopreservation of embryos, I havecited reasons for not preserving embryos for too long when it entailsharmful psychological effects on a child born after the deaths of itsbiological parents, or when its parents are at an advanced age.However, if genetic technology develops in the near future to thepoint of making it feasible to correct genetic defects at the embryonicstage of development, then this may provide medical and moralgrounds for preserving them. Such genetic alteration would meanthat a biologically and psychologically different person would comeinto existence from the person who would have come into existencewithout genetic alteration to the embryo. Yet what matters morallyis not who comes into existence, but that if we decide to bring a personinto existence, we ensure, insofar as we can, that they not experiencesevere pain and suffering over the balance of their lives.

In time, recessive genetic disorders may become amenable tosomatic-cell gene therapy. Perhaps both recessive and dominantdisorders will be prevented by germ-line genetic alteration at an earlystage of a developing human organism. The latter would haveprofound medical and moral implications for the evolution of geneticmutation in the human species as well as for our obligations togenerations in the distant future. But the genetic technology we

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presently have already gives us considerable power to determinewhich people will exist and the sorts of lives they will have in the nearfuture.36

Department of PhilosophyUniversity of Calgary

36 I am grateful to Michael Burgess, David Donaldson, Chris McDonald,Bonnie Steinbock, and an anonymous referee forBioethics for very helpful commentson an ancestor of this paper. Work on the paper was supported by a KillamPostdoctoral Fellowship at the Centre for Applied Ethics, University of BritishColumbia, which also is gratefully acknowledged.



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Genes, Embryos, and Future People