At first glance there does not seem to be anything philosophicallyproblematic about human enhancement. Activities such as physicalfitness routines, wearing eyeglasses, taking music lessons andmeditation are routinely utilized for the goal of enhancing humancapacities. But there are a cluster of debates in practical ethics,conventionally labeled as “the ethics of humanenhancement”, that do raise philosophical questions. Thesedebates include clinicians’ concerns about the limits oflegitimate health care, parents’ worries about theirreproductive and rearing obligations, and the fairness of competitivepractices like sports and war, and the possibility of improving humanmoral agency itself. They also involve more general questions aboutdistributive justice, science policy, and the public regulation ofmedical technologies.

As usual in practical ethics, an adequate discussion of any specificdebate under this heading quickly requires orientation to the scienceand the social and political practices of specific enhancementinterventions. At each turn in these discussions, wide vistas ofbackground philosophical topics also appear for exploration. Ratherthan providing a detailed account of this whole landscape, we trace apath of core concerns that winds through the current debates on theethics of human enhancement, as a guide for those interested inexploring further.

• 1. Introduction
  • 1.1 Terminology: ‘Human’ and ‘Enhancement’
  • 1.2 Brief Historical Background
• 2. What are the Proper Limits of Health Care?
  • 2.1 Professional Domain Accounts
  • 2.2 Normal Function Accounts
  • 2.3 Disease-Based Accounts
• 3. Is it Unfair to Use Enhancements?
• 4. Should We Pursue Moral Enhancements?
  • 4.1 What are Moral Enhancements?
  • 4.2 Are We Unfit for the Future?
• 5. Do Enhancements Undermine Authenticity?
  • 5.1 Authentic Achievements
  • 5.2 Being True to Oneself
• 6. Are Enhancements Dehumanizing?
  • 6.1 Enhancement Threats to Human Nature
  • 6.2 Moral Standing and Moral Status
  • 6.3 Revisiting Eugenics
• 7. Conclusion: Military Enhancements
  • 7.1 The Context of Military Enhancements
  • 7.2 The Ethics of Military Enhancements
• Bibliography
• Academic Tools
• Other Internet Resources
• Related Entries

1. Introduction

1.1 Terminology: ‘Human’ and ‘Enhancement’

As our preface suggests, the ordinary use of ‘humanenhancement’ refers to a wide range of practices, many of whichare not explored in the enhancement ethics literature. To orient ourtour, it is important to note that usage of the terms‘human’ and ‘enhancement’ in the literaturemerit some initial clarification.

In order to avoid equivocating terms in these debates, it is useful todistinguish different uses of the term ‘human’. On the onehand, there are biological uses of ‘human’ to refer tomembers of the specieshomo sapiens. On the other hand, thereare moral uses of ‘human’ to refer topersons ormembers of the moral community. The biological and moral usesof ‘human’ are familiar in the abortion debate, wherethere is disagreement about the personhood or moral standing ofprenatal human life, and one must be careful in that context todistinguish biological and ethical/moral uses of the term‘human’ when defending one’s stance. As it willbecome clear in the following sections, in the enhancement debateequivocations between biological and ethical senses of the term‘human’ are sources of many apparent disagreements. Isthere anything special about being a member of the biological specieshomo sapiens that enhancements could threaten? Or doenhancements somehow threaten being human in an ethical sense, e.g.,being a subject who has moral rights and duties and is deserving ofrespect? Are those who criticize enhancements as dehumanizing reallythinking about the loss of other markers of the moral standing that iscommonly attributed to persons? At this preliminary stage in thediscussion, we are foreclosing neither the biological nor theevaluative senses of ‘human’ from the start but will stayalert to both until it becomes important to distinguish and relatethem.

With the term ‘enhancement’, on the other hand, it ishelpful to specify a working definition from the start. One mightsimply use ‘enhancement’ as a synonym for‘improvement’: to enhance is to improve. This definitionhas the virtue of being aligned with ordinary usage. However, in thecontext of debates about human enhancement, not all improvements tohuman capacities are on par (Agar 2024). If I take corticosteroids formy allergies, that is atherapeutic improvement, whichrestores my breathing to normal levels of functioning and health.(Agar 2024) There is not much room for reasonable debate about whetherit would be wrong to take safe and low-cost medications fortherapeutic improvements (Kamm 2005). However, in the enhancementliterature, ‘enhancements’ standardly refer tobiomedical interventions that are used to improve human form orfunctioning beyond what is necessary to restore or sustainhealth. This broad definition flows from and reflects thefoundational literature in this area (Parens 1995, Juengst 1998). andit also has several implications that are sometimes forgotten.

First, it means that simple line-drawing exercises aimed at isolatingenhancement technologies from other biomedical interventions forspecial precautionary regulation or oversight are destined to beineffective (pace Anderson 1989). This is because there areno enhancement technologiesper se. Whether a givenbiomedical intervention counts as an enhancement depends on how it isused. When ankle-strengthening surgery is used to improve abicyclist’s competitive edge, it might raise enhancementconcerns, but as a treatment for a bicyclist’s ankle injury, itdoes not. This means that the developers of even the most outréenhancement interventions will almost always be able to appeal to somecorrelative therapeutic uses to justify their research, testing, andrelease into the market (Mehlman 1999; Juengst, et al. 2024). On theother hand, simply pointing out that biomedical technologies can haveboth therapeutic and enhancement uses does nothing to collapse thelogical distinction between those uses, or to defeat the claim thatthose distinguishable uses might warrant different ethical responses(Buchanan 2011). Although the logical distinction between treatmentand enhancement is clear, as we show in Section 2, understandingexactly how to use the distinction and its moral significance arematters of debate.

Second, the term ‘enhancement’ as it is standardly used inthese debates restricts its scope to biomedical interventions, eventhough other methods of increasing normal human capacities raiseethical issues as well. Electronic and robotic tools that enable us tolisten, observe, help or harm at a distance, training designed tomaximize particular talents, and social practices that foster newforms of human relationship all come with their own trade-offs andmoral concerns. But the focus of the enhancement ethics literature isoverwhelmingly on interventions that make biological changes in humanbodies and brains, using pharmaceutical, surgical, nanotechnological,robotics or genetic techniques (Clarke, et al. 2016, Agar 2013).Standard examples include:

• cosmetic surgery (Miller, Brody and Chung, 2000; Little,1998),
• the use of performance enhancing drugs to improve athleticendurance and strength (Miah 2004; Murray 2009; Tolleneer 2013; Devine2023),
• psychopharmaceutical approaches to increasing memory, elevatingmood, and improving cognitive capacities (Elliott 1998; Whitehouse, etal. 1997; Savulescu, et al. 2011; Glannon 2011; Levy, Douglas,Kahane, et al. 2014a; Duncan 2016; Earp 2018, May 2023), and
• genetic and neurological interventions to increase the human lifespan, acquire new sensory-motor abilities, and, through “moralenhancement”, live together in more peaceable, generous, andjust ways (cf. Savulescu, ter Meulen and Kahane 2011; Harris 2016;Wiseman 2016; Johnson, Bishop and Toner 2019; May 2023).

Finally, our definition implies that enhancement interventions attemptto improve specific human capacities and traits, rather than wholepersons. Unlike such comprehensive personal-improvement strategiessuch as psychoanalysis or “the power of positivethinking”, biomedical enhancements offer a piecemeal approach tohuman perfectibility. As a result, biomedical enhancements involvetrade-offs. Comparative thinking about the value of enhancements alongdifferent dimensions of desirability is unavoidable and is usuallymore of an exercise in optimization than idealization (Brennan andMoseley 2013). If extended life span comes with prolonged frailty, orif enhanced altruism compromises survival skills, the overall value ofthe enhancement can be called into question.

1.2 Brief Historical Background

An important part of the orientation for those new to thinking aboutenhancement ethics is the ways in which current debates are shaped bythe history of earlier efforts at perfecting people. At one level,perfectionist and meliorist impulses have deep roots in Westernphilosophical and religious thinking, which both modern science andmedicine have inherited (Roduit 2016; Rothman and Rothman 2004) Mostadvocates and critics of biomedical enhancement share thesecommitments to the value of human excellence and the use of humaneffort to improve well-being and reducing suffering in the world, buthave disagreeing visions of the ideal (Roduit, Baumann, and Heilinger2013; Parens 2005). Other scholars, recalling the historicalimposition of hegemonic religious and political visions of salvationand citizenship, fear the elevation of any canonical account ofexisting human virtues, in favor of visions that prize people’scapacity to shape their own ideals through reason, autonomy, anddemocratic deliberation (Sparrow 2014; Buchanan 2011). Others,pointing to the consequences of modern individualism for the commongood (Persson and Savelescu 2012), feel confident about being able toname the constellation of existing human traits that should either bepreserved (Kass 1997; Annas 1998; Agar 2013) or enhanced (Bostrom2003). However, almost no one in this literature eschews thedevelopment and use of new medical tools for healing purposes (Kamm2005; Kass 2003). Because of this, a first step in our discussion isto scrutinize the distinction between treatment and enhancement, tosee if it can help demarcate where different melioristic idealsdiverge.

Another, perhaps more visible, backdrop for the enhancement ethicsliterature is the history of the 20th century eugenics movement, whichattempted to “breed better people” and “improve thehuman gene pool” through socially biased reproductive controlsand inducements (Wikler 1999; Buchanan, et al. 2000; Lombardo 2022).This background prompts questions about the cultural authority ofscience and the social values it can perpetuate, and it raises fearsof slippery slopes that can lead to egregious forms of oppression, byproviding a vivid recent counter-narrative to endorsements ofenhancement as a way to fulfill our obligations to future generations(Sparrow 2011; Selgelid 2013; Iltis 2016). The eugenics backdrop tendsto skew the burden of proof the other way in the debate, towards amore “precautionary” stance that gives advocates ofenhancement the burden of distinguishing their proposals from oldstyle eugenics in order to defend the parts of that ideology that theyshare (Kitcher 1997; Harris, 2007; Agar 2004).

Finally, in the historical foreground for enhancement ethics arecontemporary critiques of the commercialization (and homogenization)of beauty through “aesthetic medicine” (Bordo 1993), theevolving history of pharmaceutical performance enhancement in sports(Hoberman 1992), and the scientific career of human gene transfer and‘genetic engineering’ (Friedman 1998). Each of thesestories supports a literature of its own, which has contributedimportant insights to the broader discussion of enhancement ethics.From feminist and disability studies come critiques of themedicalization of human beauty, focusing on complicity with unjustsocial norms that can turn ordinary welfare meliorism on its head toprioritize the enhancement uses of biomedicine over standardtherapeutic applications (Silvers 1998). Meanwhile, discussions of“doping” in sport have illuminated the ways in whichenhancement interventions can undermine communal social practices thatdepend on presumptions of equality, lifting the discussion above thelevel of individual choices and transactions (Murray 1987; Murray2009). Similarly, the checkered career of human gene therapy and theemergence of human gene editing has kept on the table the need toanticipate the physical risks of putative improvements, and howdaunting they would make the foreseeable prospect of anyintergenerational “germ line” enhancement intervention(Walters and Palmer 1997; Kimmelman 2009; NASEM 2017).

All of these contextual “back-stories” to the contemporaryenhancement debates are worth exploring further. They have shapedcontemporary thinking about and reactions to enhancement proposals andprovide important cautionary tales to keep in mind when evaluatingthose proposals. At the same time, these back-stories bring their ownassumptions and biases into the discussion and can thereby complicatea fresh philosophical assessment.

2. What are the Proper Limits of Health Care?

While much of the enhancement ethics literature leans towards thoughtexperiments set in the future, it is grounded in a set of importantdebates about how health care should be defined today. In thesedebates, the claim is often made that the distinction between usingbiomedical tools to combat human disease and attempting to use them toenhance healthy human traits can provide practical guidance on a rangeof issues, including the limits of health professionals’obligations (Miller, Brody and Chung 2000), the scope of health carepayment plans (Daniels and Sabin 1994), and the prioritization ofbiomedical research protocols (Mehlman, Berg, Juengst and Kodish2011). In each of these cases, the line between treatment andenhancement is drawn to mark an upper boundary of professional andsocial obligations. Just as the concept of futile treatment is used toindicate the limits of a doctor’s obligations when furtherintervention no longer can achieve therapeutic goals, enhancementinterventions are thought to fall outside health care’s properdomain of practice by going “beyond therapy” in pursuit ofother non-medical goals (Kass 2003). This means that patients have norole-related right to demand such services from health professionals,fair insurance coverage plans may exclude them, and those who doprovide them bear a burden of justification for doing so that does notapply to “medically necessary” interventions.

As a biomedical boundary marker, the distinction between treatment andenhancement has been enshrined in policies at both professional andgovernmental levels and continues to inform much of the publicdiscussion of new biomedical advances. However, this distinction isexplicated in several different ways, which have different merits asboundary markers for biomedical research and practice. In fact, withphilosophical scrutiny, the distinction often seems in danger ofcollapsing entirely under conceptual critiques even before thequestion of its moral merits is entertained.

When it is used as a medical boundary concept, enhancement, likefutility, plays both descriptive and ethical roles. To use theseconcepts, we need to be able to identify our efforts as either futileor enhancing and we need to know what the boundary means for goingfurther. Part of the practical challenge for policymakers is that forenhancement interventions, these descriptive and moral implicationsseem to be at cross-purposes. While futile treatments do no good,enhancements are by definition and descriptionimprovementsin personal welfare. Yet, the boundary function of calling them“enhancements” in health policy settings is to place themoutside of sanctioned interventions. For a field dedicated to pursuingimproved welfare for its patients, the fact that enhancements oftenlook just like all the other improvements that health care strives toachieve makes it difficult to discern when an interventiontransgresses the normative boundary that the concept purports tomark.

This has provoked three major ways of operationalizing the enhancementconcept, each of which seeks to redress the weaknesses of itspredecessor.

2.1 Professional Domain Accounts

The first approach to defining the line between treatment andenhancement appeals to the health professions’ conventionalvision of their proper domain. Accordingly, “treatments”are any interventions that the professional standards of care endorse,while “enhancements” are any interventions that theprofessions declare to be beyond their purview. Attempts byprofessional societies to police their own frontiers by discouragingparticular practices as “enhancement” rather than“treatment” reflect this approach, as do appeals to“community standards” by health care payers seeking todistinguish “elective” from “medicallynecessary” interventions for payment.

For those committed to a particular account of the goals of healthcare, this approach can offer normative guidance for internalcriticism of suspect professional practices (Kass 1985). But ofcourse, there are numerous competing philosophies of health care, noneof which command universal allegiance within the health professions.In fact, this approach also resonates well with those who argue thatthe health professions have no intrinsic domain of practice, beyondthat which they can negotiate with patients (Good 1994). For thoseinfluenced by this libertarian view of professional autonomy, thenormative lesson for professionals concerned about their obligationsin specific cases can be simple: whatever interventions their patientswill accept can be considered “treatments”, while“enhancements” are simply those interventions whichindividual health professionals refuse to provide (Engelhardt 1990).Unfortunately, medical historians and sociologists point out that thehealth professions have always been adept at adapting to the culturalbeliefs and social values of the institutions and communities theyserve. This is done by ‘medicalizing’ new problems so thatthey come to be seen as a legitimate part of medicine’sjurisdiction (Conrad 2007). Given the health professions’philosophical pluralism and political autonomy, their own conventionsseem to provide no principled way to exclude new interventions fromtheir domain. To the extent that useful “upper boundary”concepts are required at the policy level (e.g., for societies makinghealth care allocation decisions) this impotence is an importantfailing for this approach to drawing the distinction.

2.2 Normal Function Accounts

There is another approach to interpreting the treatment/enhancementdistinction that seeks to provide a firmer theoretical foundation fordelimiting legitimate health care needs. On this approach, to behealthy is to be able to do all that appropriately matched members ofone’s own species can do, in our case what human beings ofsimilar age and gender can do. Legitimate health care needs or“health problems” or “diseases” or“maladies” are all characterized by a fall from that levelof functional capacity. All proper health care services, therefore,should be aimed at getting people back to “normal”, e.g.,restoring an individual’s functional capability to thespecies-typical range for their reference class, and within that rangeto the particular capability level which was the patient’sgenetic birthright. Interventions which take people to the top oftheir personal potential (like athletic training) or beyond their ownbirth range (like growth hormone), or to the top of the range of theirreference class, or to the top of the species-typical range, or beyond(!), are all to be counted as enhancements and fall successivelyfurther beyond the responsibility of medicine or health care.

The advantage of the normal function account is that it provides asingle (relatively) unified goal for health care, towards which theburdens and benefits of various interventions can be compared,measured, balanced, and integrated. Normal functionalists can usephysiology to determine when they’ve achieved the speciestypical range and clinical histories to determine when they’vebrought a patient up to the baseline of his or her personal capabilityrange.

Some critics of the normal function approach take issue with its focuson the “species-typical range”, arguing that it isinsensitive to the diversity of ways in which human beings canflourish in life. They point out that those born with disabilities maybe wary of biomedicine’s “fatal attraction tonormalizing” (Silvers 1998; Asch and Block 2011). Moreover, evenwhen no amount of treatment can give someone “speciestypical” functioning, there may be compensatory technologiesthat can actually expand their range of opportunities beyond the norm(Silvers 1998). Should powered wheelchairs be designed to slow andstop at the same distance that walking humans would succumb tofatigue, in order to keep them from “enhancing” theirusers’ abilities? By the same token, the naturally gifted mayfind that they have no claim to treatment for injuries or accidentsthat merely bring them down into the “normal range”. Ifour champion thinkers, athletes and saints can legitimately claimtreatment for problems that impair their species-optimal functioning,bringing the rest of us up to their levels should count as properhealth care as well. But that leaves only the most extremeimprovements on the other side of the “enhancement”boundary: if our species champions are the benchmark, onlyinterventions that create capacities no human has had before wouldfall beyond medicine’s proper domain. Individualizing theoptimal functional range to individual genomic potentials will notresolve this problem, of course, to the extent that our genomesthemselves become biomedically malleable. Establishing the“species-typical norm” for a particular human function isa difficult enough task, even where descriptive statistics can help.But when the boundary is “optimal” not“normal” functioning, the evidentiary foundations of theapproach begin to come apart (Sculley and Rehman-Sutter 2008).

The second serious problem for the normal function approach is thechallenge of prevention. While some efforts at health promotion, suchas exercise, straddle the border of medical responsibility, manypreventive interventions (i.e., vaccines) are widely accepted aslegitimate parts of medicine’s mission and are located squarelyon the treatment side of the enhancement boundary. One of the ways toprevent disease is to strengthen the body’s ability to resistpathological changes before any diagnosable problem appears. But tothe extent that prevention attempts to elevate bodily functions abovethe normal range for the individual (and, in some cases, even thespecies typical range), it seems to slide into what the normalfunction approach would call enhancement. If the normal functionaccount is taken seriously as a biomedical boundary marker, how doesone defend this kind of prevention? Conversely, if preventiveinterventions like these are acceptable in medicine, what can it meanto claim that researchers and clinicians should be “drawing theline” at enhancement? (Juengst, et al. 2024)

2.3 Disease-Based Accounts

Probably the most common rejoinder to the problem of prevention is todistinguish the problems to which they respond. Treatments areinterventions that address the health problems created by diagnosablediseases and disabilities:maladies in the helpful languageof Gert, Culver and Clouser (2006). Enhancements, on the other hand,are interventions aimed at healthy systems and traits. Thus,prescribing biosynthetic growth hormone to rectify a diagnosablegrowth hormone deficiency is legitimate treatment, while prescribingit for patients with normal growth hormone levels would be an attemptat positive genetic engineering or enhancement (Berger and Gert 1991).On this account, to justify an intervention as appropriate medicinemeans to be able to identify a malady in the patient. If no medicallyrecognizable malady can be diagnosed, the intervention cannot bemedically necessary and is thus suspect as an enhancement. This wouldclear the way for safe and effective genetic “vaccines”against predictable muscle damage (even if they provided better thannormal damage resistance) but would screen out as enhancements effortsto improve traits that were at no diagnosable risk of deterioration(Juengst 1997).

These accounts have the advantage of being simple, intuitivelyappealing, and consistent with a lot of biomedical behavior. Maladiesare objectively observable phenomena and the traditional target ofmedical intervention. We can know maladies through diagnosis, and wecan tell that we have gone beyond medicine when no pathology can beidentified. Thus, pediatric endocrinologists discourage enhancementuses of biosynthetic growth hormone by citing the old adage “Ifit ain’t broke, don’t fix it”. This interpretationis also at work in the efforts of professionals working at theboundary, like cosmetic surgeons, to justify their services. Theyclaim to be relieving diagnosable psychological suffering (mentalmaladies) rather than satisfying the aesthetic tastes of theirclients, and insurance companies insist on being provided with thatdiagnosis before providing coverage for such surgeries.

On the other hand, disease-based accounts also face at least twoobjections. The first is one they share with the Professional Domainaccount: the problem of biomedicine’s infamous nosologicalelasticity. It is not hard to coin new maladies for the purposes ofjustifying the use of enhancement interventions (Carey, Melvin andRanney 2008). Unless some specific (and usually contentious) theory ofdisease is employed to give this approach its teeth, it puts the powerfor drawing the boundary back into the profession’s hands andraises the same worries about the social domain accounts (Parens2013). The more important practical problem is that no matter how theline is drawn, most biotechnological interventions that could be seenas problematic if used as enhancements will not need to be justifiedas enhancements in order to be developed and approved for clinicaluse. This is because most such interventions will also have legitimatetherapeutic applications. Indeed, most biomedical tools with potentialfor enhancement uses will first emerge as therapeutic agents. Forexample, general cognitive enhancement interventions are likely to beapproved for use only in patients with neurological diseases. However,to the extent that they are in high demand by individuals sufferingthe effects of normal aging, the risk of unapproved or“off-label” uses will be high (Whitehouse, et al.1997).

This last point is critical for policy purposes, because it suggeststhat, in countries like the USA, the real challenge may not beregulation of the development of enhancement interventions, but ratherthe regulation of downstream “off-label” uses oftherapeutic interventions for non-medical, enhancement purposes.(However, c.f., Moseley and Fröhlich (2025) discuss cases ofnon-invasive brain stimulation technology that was first developed andtested on healthy subjects to evaluate boosts in creativity and waslater utilized for therapeutic purposes.) The policy problems thenbecome problems about controlling access and use of certaininterventions, rather than their development. Of course, the fact thata certain type of intervention is declared illegal for physicians todispense, does not immediately imply that it is morally wrong foranyone to pursue or for other competent professionals to provide.These realities have pressed those who would use thetreatment/enhancement distinction for policy purposes to articulatethe moral dangers of biomedical enhancement more clearly. Even ifdoctors eschew such use on professional ethical grounds, are thereindependent moral reasons why individual athletes, parents, studentsor other “consumers” of enhancement interventions, shouldturn away from their availability?

3. Is it Unfair to Use Enhancements?

One type of human enhancement that has received extensivephilosophical attention is the use of biomedical interventions toimprove the physical performance of athletes in the context of sports(Miah 2004; Murray 2009; Tolleneer, et al. 2013; Devine 2023). Onereason athletic performance enhancement garners so much attention isbecause of its currency, given the epidemic of doping scandals incontemporary sport. Another reason, however, is that it serves as aparadigm case for teasing out important dimensions of the problem: itinvolves measurable improvements in biological capacities in a socialcontext that is both well outside health care and defined by clearrules of engagement.

At first impression, the ethical problem with performance enhancementin sport would seem to be simply a problem of cheating (Schermer,2008a). If the rules of sport forbid the use of performanceenhancements, then their illicit use confers an advantage to usersagainst other athletes (who either accept the rules of the game or donot have access to the enhancement interventions). That advantage, inturn, can create pressure for more athletes to cheat in the same way,undermining the basis for the competitions at stake and exacerbatingthe gap between those who can afford enhancements and those who cannot(Murray 1987, Sparrow 2015, Devine 2023).

Extrapolating from sports to a broader competitive view of society atlarge, critics argue that the widespread social acceptance ofenhancement interventions would exacerbate inequalities and createunfair advantages for privileged individuals. That situation is likelyto result in the development of sharp divides between enhanced andunenhanced populations, or between an elite class of“genobility” and an underprivileged class of“genpoor”, raising distributive justice and human rightsconcerns (Mehlman 2003, 2009; Buchanan, et al. 2000; Sparrow2011).

Much of the rhetoric about “doping” assumes the very claimthat needs to be established by argument: that the rules of sport (orthe norms of social advancement) ought to ban the use of biomedicalenhancement. The rules of a sport can be changed. Novel performanceenhancing technologies and training methods are regularly integratedin sports. Thus, whether it is morally permissible to introducespecific biomedical enhancements in sports, in general and inparticular sports, depends on considerations about fairness,distributive justice, and the goals of sport itself (or the goals ofparticular sports). Fairness issues around equitable access toenhancements can sometimes be addressed directly, such as theInternational Olympic Committee’s decision to provide all teamswith “FastSkin” swimming suits at the Sydney Olympics. Inother cases, inequalities may come to be accepted as unfortunate butnot unjust. For example, when an equatorial country’s ski teamdid not have access to artificial snow and so could not compete evenlywith the ski teams of northern countries.

If enhancement interventions can either be distributed fairly or theinequities they create can be written into the rules of the particularsport in question as part of the given advantages of the morefortunate, then participants no longer face a fairness problem. Forthose who can afford it, for example, what would be ethically suspectabout mounting a mirror image of the “Special Olympics”for athletes with disabilities: a “Super Olympics”,featuring athletes universally equipped with the latest modificationsand enhancements? (Munthe 2000)

For answers to that challenge, the critics of biomedical enhancementneed to dig beyond concerns about the fair governance of sports to adeeper and broader sense of “cheating”, in terms of thecorrosive effects of enhancement on the integrity of admirable humanpractices (Loland 2002; Schermer 2008a). On this view, to the extentthat biomedical shortcuts allow specific accomplishments to bedivorced from the admirable practices they were designed to reflect,the social value of those accomplishments will be undermined. Ifone’s good grades are gained by drug fueled“cramming” rather than disciplined study, their value asevidence of learning diminish. This means that for institutionsinterested in continuing to foster the social values for which theyhave traditionally been the guardians, choices will have to be made.Either they must redesign their sports to find new ways to evaluateexcellence in the admirable practices that are not affected byavailable enhancements, or they must prohibit the use of the enhancingshortcuts. However, knowing which way to go suggests that one has atheory of the social practice at risk and of the values that animateit. The case of sport again leads the way down this path in theliterature, perhaps because, unlike most important social practicesthat might be susceptible to enhancement shortcuts (likechild-rearing, education, love, politics, and spiritual growth), thestakes are low enough to allow for some deliberate policymaking at theinternational level.

For example, one prominent theory that has influenced the work of TheWorld Anti-Doping Association (WADA), the international organizationcommitted to policing performance enhancement in elite sport, is theview that “just as healing is the point or goal or end ofsurgery, so the virtuous perfection of natural talents is the point orgoal or end of sport” (Murray 2009). This statement has severalimportant features for the enhancement debate. Sport is concerned withcelebrating differences in natural talents and the virtues that can bedisplayed in attempts to differentiate one’s own talents evenfurther. The virtues that sport celebrates are socially admirablehabits and traits in and of themselves, and their promotion is whatgives sport social value as a practice. However, within the practice,the virtues are instrumental (as either side-constraints orfacilitators) to the perfection of the athlete’s naturaltalents—i.e., to their differentiation from other people’stalents. Although the key role of hierarchical ranking in sport isoften ignored in the rhetoric of sports organizations, philosophers ofsport acknowledge that fixation with hierarchical ranking—withcompetition, contest, score-keeping, record-breaking, championship,victory and defeat—is pervasive in the everyday practice ofsport (Coakley 1998) and that “comparing and ranking two or morecompetitors…defines sports characteristic socialstructure” (Loland 2002, 10). Sport exemplifies a system ofvalues, virtues, and practices explicitly designed to rank peoplehierarchically based on their naturally inherited and virtuouslyperfected traits, celebrating the best specimens as champions. What isunfair about biomedical enhancement, on this view, is thatenhancements undermine the traditional role of sport, and its idealsof virtue and personal effort: enhancements obscure the distinctionbetween to distinguish individuals who naturally inherited theirtalents from their progenitors from those who artificially acquiredthem from their physicians (Sandel 2004).

But this outcome seems to display the very problem that the fairnesscritique of enhancement was meant to combat: the danger of fomentingdistributive injustice by creating social hierarchies of advantage onarbitrary grounds (Tännsjö 2000; Tännsjö 2005). Onthe one hand, of the many ways humans use inherited traits to createinterpersonal hierarchies, athletic competition is amongst the mostbenign. When it is “just a game”, comparativeinterpersonal ranking in terms of genetic identity in sports is awelcome substitute for blood feuds, racism, and genocide. But whensport becomes a matter of national pride and a source of economicopportunity, athletic losers risk more than simply admiration andsocial status: like insurance applicants with geneticsusceptibilities, less naturally talented athletes risk access toimportant social benefits and potential life plans. In this regard,the challenge that performance enhancement poses to sport is itsindictment of the accepted social practice itself rather than itsthreat to undermine it. The availability of biomedical abilities toundermine competition simply raises the question: are there ways toenjoy, appreciate and even show off our bodies and abilities withoutrequiring someone else to lose social standing on genetic grounds?

Enhancements might reveal inherent injustices within traditionalhierarchies in sports, rather than merely create unfair advantagesthat reward inherited genetic traits and penalize athletes who,through no fault of their own, lack them. In this way, enhancementscould promote fairness in sports rather than diminish it. We willexamine below whether fairness arguments have a similar impact indiscussions of enhancement within the domain of other socialpractices, such as parenting, education, or military service.

4. Should We Pursue Moral Enhancements?

4.1 What are Moral Enhancements?

When discussing the notion ofmoral enhancement, two salientquestions arise: (1) What does ‘moral’ refer to in thiscontext? and (2) How do we distinguish moral enhancement from othertypes of enhancement? (Moseley 2025) Regarding the first question, itis crucial to distinguish moral enhancements from technologicallyinduced improvements in mood, emotion, cognition, creativity, orimagination, even though such capacities are usually involved in moralimprovement.

Mark Rowlands argues that most discussions of moral enhancement failto address these preliminary questions and contends that a substantiveconception of morality is necessary to develop an intelligible andconsistent account of moral improvement (Rowlands 2018). To determinewhether our moral capacities are improved by enhancing certain humanabilities, we must first clarify what constitutes a moral improvement.For example, a Kantian might understand moral enhancement asstrengthening our capacity to evaluate motives and act from the maximof the categorical imperative. An Aristotelian virtue theorist wouldemphasize improving capacities that foster practical wisdom. A Humeansentimentalist might contend that moral improvements involvestrengthening capacities for empathy or sympathy. (Rowlands 2018)These examples simplify the complexity of each metaphysical theory,but they show the difficulty of assuming a single, straightforwardsense of “moral improvement” (Moseley 2025).

These rival philosophical stances also complicate the notion of acommon moral baseline, i.e., a standard of normal human moralfunctioning from which any improvement above that threshold wouldcount as an enhancement. The Kantian, Aristotelian, and Humeanaccounts diverge on this point. Rowlands offers a sketch of how eachframework might be used to specify what counts as a moral enhancement.(2018)

An alternative strategy for avoiding definitional complexity is toexamine particular cases that clearly involve the relevant moralissues. Douglas (2008), for instance, examines biomedicalinterventions that target specific moral failings, such as strongaversions to certain racial groups or impulsive aggression. Thesecases sharply raise the ethical question: is it morally permissible,or even obligatory, to use biomedical interventions (e.g.,psychopharmacology, psychedelic drugs, non-invasive neuromodulation,electroconvulsive therapy, deep brain stimulation) to make someoneless racist or less prone to violent acts?

4.2 Are We Unfit for the Future?

Interest in moral enhancement has surged over the past decade. Much ofthis attention to the topic is in direct response to the influentialwork of Igmar Persson and Julian Savulescu (2012), who argue that thesurvival of our species depends on the urgent development andwidespread adoption of moral enhancement technologies. They argue thatglobal collective-action problems cannot be solved by traditionalmeans or by cognitive enhancement alone. Worried that an unregulatedexpansion of cognitive enhancements might amplify injustice and socialharm, they argue that widespread access to cognitive enhancementshould be preceded, or accompanied, by enhancement of our moralfaculties. Improved moral discernment and reasoning, keener senses ofempathy and fairness, and deeper sense of solidarity, they contend,would help mitigate the potential social harms by ensuring that theusers of enhancement technologies are equipped to do so responsibly(Tennison 2012; Persson and Savulescu 2012). They further argue thatmoral enhancements will be required to establish enough cooperationamong societies to solve the problems of war, overpopulation, climatechange, pandemics, and other global crises that may drive human beingsinto extinction. On broadly welfarist/utilitarian grounds, theycontend that there is a moral duty to develop and deploy moralenhancement technologies to preserve human life on Earth.

Critics argue that achieving the moral upgrades in the mannersuggested by Persson and Savulescu would require intrusive anddraconian social mechanisms: the very kinds of social control thatthese moral enhancements were intended to render unnecessary (Sparrow2014b; Harris 2016; Azevedo 2016). Others question the criteria bywhich moral upgrades would be defined or measured (Joyce 2013; Craigie2014; Wiseman 2016; Hauskeller and Coyne 2018; Johnson, Bishop andToner 2019; Paulo and Bublitz 2019). Would the morally enhanced stillbe permitted to regard certain actions as supererogatory rather thanobligatory, or would more be expected of them? We need not aspire torequire superhuman virtues, such as angels might possess, but shouldthe morally enhanced at least be regarded as saints? If so, by whoseconception of sainthood? Once again, a panorama of alternativephilosophical traditions opens for exploration down this road,offering no quick resolution for policy.

It is also worth remembering that specific biomedical enhancementswill never yield comprehensive improvements in moral character, ifonly because moral character is not reducible to the biologicalsubstrates of brains and genes. At best, moral enhancement can modifyspecific biological functions in ways that increase the chances thatacting in one manner (e.g. telling the truth) while decreasing thechances of acting in another (like lying) which in certain contextsmay actually be the more virtuous thing to do. This double-edgedfeature of biomedical enhancement means that every morally enhancingintervention risks being, at the same time, a morally disablingone.

This observation suggests that, despite the claims of its defenders,biomedical enhancement is not always well suited to a melioristicethic aimed at improving human welfare. Often a step forward for somepurposes is also a step back in other contexts. Many enhanced peopleare, in corresponding ways, disabled – and the same may hold for theirteams, families, or communities. For example, an enhancement thataccelerates reflexes might benefit military pilots in combat butsignificantly increase the risk of errors among commercial airlinepilots. This illustrates how enhancements involve context-dependenttrade-offs that are beneficial in one situation yet harmful or unfairin others. If we focus our policies on recognizing that mostenhancements come with trade-offs, we might be able to orient ourpublic policy away from abstract regulatory or compensatory models of“enhancement” and toward a focus on the specific social andinstitutional contexts in which particular interventions might provetoo risky or unjust.

5. Do Enhancements Undermine Authenticity?

Critics of biomedical enhancements often express concerns aboutenhancements undermining authenticity. These concerns often expressthe fear that enhancements could deprive persons of characteristicsessential to their sense of self – such as endurance, determination,growth, faith, or luck – by substituting “hollow victories”for authentic achievements. Critics argue that this loss ofauthenticity diminishes personal character (Sandel 2007), alienateshumans from themselves and their communities (Agar 2013), and weakensbonds of solidarity with those who choose not to enhance themselves(Sparrow 2014). To translate these intuitive concerns into morerigorous philosophical arguments, we must attend carefully to theparticular contexts in which the enhancements occur. For instance, theauthenticity concerns that arise when parents choose to enhance theirchildren differ markedly from those that emerge when adults choose toenhance themselves. Likewise, therapeutic uses of the sametechnologies may invite different authenticity considerations.(Elliott 2011). In this section, we identify several central argumentswithin this broader literature.

5.1 Authentic Achievements

One influential line of argument claims that biomedical enhancementsundermine authenticity because individuals cannot rightly claimpersonal credit for accomplishments produced through suchinterventions. According to this view, the biomedical interventionsthat caused improvements in our capacities would supersede our ownagency in authoring the achievement (Kass 2003; Sandel 2007).Defenders of this perspective argue that, whereas education, training,and practice proceed through “speech and deeds” that arecomprehensible by those who are learning a new skill, biomedicalenhancements exert their effects on a subject who “is not merelypassive but who plays no role at all. In addition, he can at best feeltheir effects without understanding their meaning in humanterms” (Kass 2003).

One common reply to this argument is that when someone freely chosesto use an enhancement on the basis of reflection and deliberation, bymeans of the “speech and deeds” that guide ordinary self-improvement,it is unclear why the enhancement should be considered passive orinauthentic (Kamm 2005). As Joshua May observes, “mind-alteringdrugs have likely proliferated throughout human cultures because theypromote meaningful and authentic improvements in creativity, bonding,collaboration and group solidarity” (May 2023). Moreover, justas we hold those with enhanced abilities to higher standards ofresponsibility for negligence and harm (Mehlman 2003), ourexpectations for enhanced achievements may be correspondingly high(Carter and Pritchard 2019). In both cases, however, the enhancedagent’s authorship of their achievements and agency inself-improvement remain intact (Cole-Turner 1998).

Critics of biomedical enhancements that appeal to considerations ofauthenticity often acknowledge that enhanced individuals do authortheir accomplishments, but they question whether those successes carrythe same value as “authentic”, unenhanced achievements(Habermas 2003; Sandel 2007; Bublitz and Merkel 2009). They argue thatwhen a marathon runner gains endurance chemically rather than throughtraining, or when a mystic attains Nirvana through psychedelic therapyrather than meditation, each misses something essential to the valueof the accomplishment. As Schermer (2008a) and Spitzley (2018) note,the outcomes of such activities cannot be separated from theactivities themselves: their values lie in the processes they rewardas much as in the results they yield. For discussion of three “easyshortcut” arguments of this kind, see Schermer 20008a and Moseley andMurray 2023 for critical evaluation.

Even if these criticisms show that unenhanced achievements arevaluable for reasons that are not shared by enhanced ones, they do notestablish that the unenhanced route is, overall, superior. They merelyestablish that the two forms of achievement are valued differently.Enhanced achievements may have their own distinctive worth.Historically, the character-building struggles we admire seem adept atkeeping pace with our tools. From this perspective, biomedicalenhancements may serve as important new tools for self-creation thatwe should consider embracing (DeGrazia 2000; Agar 2004). For adetailed philosophical study of the nature and value of achievement,see Bradford (2015).

5.2 Being True to Oneself

In addition to these types of authenticity concerns, critics of humanenhancement argue that biomedical enhancements can, and often do,threaten the authenticity or identity of individuals. Do enhancementsundermine the authentic self-authorship or personal identity?Authenticity is widely understood to be a matter of being “trueto oneself.” Yet many contributors to these debates neglect toclarify their assumptions about the nature of the self and what ittakes to be true to it – or to author oneself. As Lionel Trilling(1971), Charles Taylor (2991) and Charles Guignon (2004) haveobserved, it is no simple task to characterize the self to whichauthentic individuals are true.

These questions raise two broad categories of philosophical problemstypically classified as philosophical questions about personalidentity: metaphysical and practical problems (Schechtman 2007).Metaphysical problems concern the criteria for being a person eitherat a given time (synchronic identification questions) or over time(diachronic identification questions). In contrast with metaphysicalquestions aboutwhat it is to be a person, the practicalproblems of personal identity that are primarily concerned withwho a person is (Schechtman 2007; Moseley 2012). Thepractical questions of personal identity often emerge from thefirst-person perspective, when one seriously asks, “Who amI?”, and tend to surface in times of reflection on one’sdeepest commitments. This type of reflection is often not an exercisein philosophy: more often, it is an attempt to understand one’sown character and core commitments (Korsgaard 1996). The decisions andchoices that result from this kind of reflection are essential to theprocesses ofself-discovery andself-creation.

This form of self-discovery is a creative and ongoing process ofreflecting on our moral experience and sharpening and re-valuating ourcommitments. The concept of self-creation may seem paradoxical orincoherent if it is understood as a metaphysical explanation ofone’s relation to oneself. How can a person create, author, orconstitute themselves unless there is a self that already exists to dothe creating? The paradox is resolved if we understand‘self’ in this context as referring to one’spractical identity (Korsgaard 1996; 2008). A practicalidentify is “a description under which you value yourself, adescription under which you find your life to be worth living and youractions to be worth undertaking.” (Korsgaard 1996) Thisconception of personal identity is agnostic about the metaphysics ofpersonhood: it can apply equally to an immaterial soul or to a harddeterministic vision of the activity of the human brain.

Practical identities are both discovered and created by individuals.Do biomedical enhancements undermine one’s capacity to forge apractical identity? One would need to look at each specificenhancement technology to determine whether it would undermine thatcapacity. For instance, if a “pro-social enhancement” wereto make someone more conformist, unreflective, or susceptible tomanipulation by advertising or political propaganda, it would clearlycompromise authenticity. Authentic persons usually reflectively affirmtheir practical identities, their relationships to others, and to theworld that they inhabit (Moseley 2012). Enhancements that diminish oreliminate those capacities would thereby undermine authenticity. Theseconsiderations intersect with our earlier discussion of moralenhancements in Section 4.2.

Given the complexity of these debates, and the frequent conflation ofmetaphysical and practical questions about personal identity andself-creation, it is no surprise that little consensus existsregarding whether enhancements undermine authenticity of the self. Itis also worth noting that some participants in these debates havemoved away from framing these issues as debates about personalidentity, since that terminology presupposes that we are essentiallypersons. Animalists, who hold that we are fundamentally biologicalorganisms (Homo sapiens), reject that assumption. For thosesympathetic to the Animalist perspective, the arguments about moralstanding and status discussed in Section 6.2 offer an alternativeframework for addressing central ethical issues about the self in theenhancement literature.

6. Are Enhancements Dehumanizing?

6.1 Enhancement Threats to Human Nature

In the background of the debates over the boundaries of medicine andthe ethics of self-improvement is a set of philosophical concernsabout what new biomedical enhancement technologies imply for ourshared understanding of human nature and the future of our species.Critics often invoke “dystopian nightmares,” and worrythat enhancement interventions may rob us of central normativefeatures of our identity as human beings (Mehlman 2012). FrancisFukuyama influentially argues that biomedical, especially genetic,enhancements threaten our very humanity (Fukuyama 2002). Otherbioconservative critics, such as George Annas, go further and arguethat the use of genetic enhancements would be a crime against humanityand demand the creation of a “human species protectiontreaty.” (Annas 2005) They also contend that by taking humanevolution into our own hands and directing it towards the emergence ofa new species, we risk altering “the essence of humanityitself” and thereby changing “the foundation of humanrights.” (Annas, et al. 2002)

These concerns are supported by the language in theUniversalDeclaration of Human Rights, which recognizes the inherentdignity and “equal and inalienable rights of all members of thehuman family” as the basis for “freedom, justice and peacein the world” (United Nations General Assembly 1948). Theseauthors fear that genetic enhancement is likely to lead to theemergence of post-humans who are more powerful than us and mightperpetrate crimes against humanity, such as enslavement or genocide.Others, such as Habermas (2003), argue that the “ethicalself-understanding of the species” is jeopardized by geneticselection or editing practices that parents might use in conceivingand raising their children. These bioconservative arguments focus onthe concerns that enhancements will threaten moral equality, humandignity, and human rights.

By contrast, enhancement enthusiasts, often described astranshumanists, welcome the possibility that biomedicalinterventions might transform human nature for the better. Some evenlook forward to the emergence of trans-humans or post-persons as thenext step in intentionally directed human evolution (Hughes 2004;Harris 2007; Savulescu 2009). At stake in these debates is whether, orhow much, normative weight to assign to features of human nature thathave traditionally been taken as given (e.g., the families into whichwe are born and our natural talents and abilities) or inevitable (suchas, pain and ageing), and whether those features of human nature placemorally significant limits on enhancement.

Moral philosophy has a long history of making normative appeals tohuman nature. Stevenson, et al. (2017) survey thirteen influentialaccounts of human nature across Eastern and Western intellectualtraditions. There are thorny philosophical issues about whether suchappeals are ever legitimate. Ever since David Hume warned us to notderive an “ought” from an “is”, moralphilosophers have been skeptical of making strong inferences aboutwhat ought to be done directly from empirical claims about humannature. However, virtue ethicists have been more comfortable withadopting an empirical and naturalistic approach to human nature as thebasis for understanding what constitutes human well-being andflourishing (Hursthouse 1999, Foot 2001). Explaining what is worthcherishing about being human is an intuitive starting point for makingsense of ourselves, our relationships with other human beings, and ourplace in the world. The task of getting clear about what we do andshould value about being human has important implications for theethics of human enhancements.

Defenders of bioconservatism often emphasize three features of humannature as especially worth preserving. The first feature is humanvulnerability. According to one prominent bioconservative view, humanbeings are creatures that suffer, age and die, and our struggle todeal with this vulnerability is a central aspect of what makes humanlife valuable (Parens 1995, Habermas 2003). Within this camp, severalsubgroups can be distinguished. “Life cycle traditionalists”criticize ambitions to control the human ageing process or extend thehuman life span (Callahan 1995). “Personalists” valorize theways in which human limitations are humbling and encourage modesty(Fitzgerald 2008). “Psychopharmaceutical Calvinists” cautionagainst quick pharmacological fixes for melancholy or sadness (Elliot1998). They warn that “easy shortcuts” corrode character,diminish the inherent value of suffering, and diminish the complexityand richness of human practices (Shermer 2008a; Moseley and Murray2023). The second (set of) cherished features are embodiment andspecies membership. Species preservationists and environmentalistsemphasize our biological embeddedness in nature and our place within aparticular evolutionary lineage. They contend that enhancements thatblur or bend “species boundaries” by attempting to direct evolutionendanger the integrity of both humanity and its ecological relations.(McKibben 2004). The third feature is sociality. Human beings areinherently social creatures that relate to one another through acomplex nexus of interpersonal relationships, commitments, andhierarchical structures (Liao 2006a; Liao 2006b).

Critics of bioconservatism argue that efforts to protect thesecherished human traits by trying to insulate human nature fromenhancement interventions are flawed in several ways. First, there islittle reason to believe that enhanced humans would lose their sensesof vulnerability, embodiment, connection with nature, or sociality.These traits may manifest differently among post-humans, just as theyhave evolved across human history. Indeed, transhumanists argue, thereare no static features of the human condition: human vulnerabilitiesto our environment have steadily decreased over history, our moralkinship communities have expanded, and our tolerance for oppressiveforms of social organization has dwindled (Savulescu 2009).Accordingly, appeals to “human nature” in abstraction offer limitedguidance in deciding which vulnerabilities to preserve, whichloyalties to honor and respect, and which social structures to defendand develop. Where a biomedical intervention alters one of thesedimensions of human nature, it signals that the moral stakes are high.But those stakes are not always about what might be lost from thehuman experience, but also what may be preserved or perpetuated.

Second, even if preserving human nature in its current form weredesirable, banning enhancements cannot achieve this goal. As Juengstobserves, “species are not static collections of organisms thatcan be ‘preserved’ against change like a can of fruit;they wax and wane with every birth and death and their geneticcomplexions shift across time and space” (Juengst 2017). In ourcase, almost everything we do influences this evolutionary process. Toargue that everyone has the right to inherit an “untampered genome”only makes sense if one were to take a snapshot of the human gene poolat a given instant and reify it as the sacred “genetic patrimonyof humankind”—an approach that some critics nearly adopt.(Juengst 2009)

6.2 Moral Standing and Moral Status

As noted in Section 1.1, there is a persistent risk in enhancementdebates of conflating the biological and ethical senses of the term‘human’. In this debate, the risks are even greater, giventhat the dispute rests on how to best understand being human. In thebiological sense, ‘human’ refers to members of the speciesHomo sapiens; to be human in this sense is to be a member ofthat species. In the evaluative sense or moral sense,‘human’ refers to being a member of the moral communityand having the accompanying moral rights that are owed to members ofthat community. Buchanan (2013) discusses these conceptual issues aspart of an in-depth examination of the moral foundations of theinternational legal human rights system (Buchanan 2013).

One type of general objection to this debate, often frompost-modernist quarters, is that discussing human nature at all is anintellectual faux pas, and that we are beyond this sort of“essentializing” discussion (DeGrazia 2012). Thisobjection is weak. Even if there are no essential human properties, wecan still articulate a conception of human nature that identifiescharacteristics most human beings share that are recalcitrant to beingremoved or are significantly altered by education, training, orindoctrination, and that play significant explanatory roles in bothwidespread human behavior and differences between humans and otheranimals (Buchanan 2011, DeGrazia 2012).

It is also crucial to distinguish two possibilities that often becomeconflated in these debates: (1) the emergence of new traits that arethe outcomes of genetic interventions that could produce a newbiological species, and (2) the emergence of individuals who wouldconstitute a new and superior kind of moral agent. The former would beHomo maximus, whose qualitative difference fromHomosapiens is vast (Degrazia 2012, 82). The latter wouldyieldpost-persons –beings with higher moral status thancurrent moral agents. Buchanan (2011) and DeGrazia (2012) providecareful treatments of these distinctions and their implications.

In the context of debates about transhumanism, it is useful todistinguish between moral standing and moral status, following AlanBuchanan’s influential framework (Buchanan 2011; 2013).Individuals who have moral standing count morally in their own right.For example, on hedonistic utilitarian grounds, sentient beings havemoral standing because they can experience pleasure and pain; forKantians, moral standing is conferred by the capacity for practicalreason. Whereas moral standing is a non-comparative notion,moralstatus is comparative. It concerns the degree to whichindividuals’ interests matter morally. Thus, both chickens andhumans possess moral standing as sentient creatures, but humans havehigher moral status because they possess greater capacities forexperiencing pleasure and pain and agency.

We typically assume that human beings occupy the highest moral statusamong earthly creatures. The possible emergence of post-humans orpost-persons could challenge our position in the hierarchy of moralstatus. If post-humans have a higher moral status than current humanbeings while retaining the same moral standing, what moral objections,if any, could we raise? (Here it may be helpful to return to thediscussion of moral enhancement in Section 4.) The more troublingpossibility is that post-persons might have higher moral standing thanwe do, thereby violating the widely heldmoral equalityassumption: the view that all moral agents share equal moralstatus.

Some transhumanists, such as James Hughes (2004), argue that we shouldadopt a more optimistic and inclusive stance towards recognizing thepolitical and moral rights of cyborgs and post-humans in futureliberal democracies. Critics acknowledge that post-humans mightrightfully claim the same natural rights as current humans by virtueof their capacities but argue that creating post-humans wouldundermine the link between being human and human rights, much as thediscovery of rational extraterrestrials might. This shift could havethe effect of potentially disenfranchising some existing humans, suchas infants or persons with severe neurological disabilities, whocannot demonstrate the functional capacities associated with moralagency.

At the same time, if the post-humans actually have enhanced cognitiveand moral capacities, they might claim expanded rights proportional tothose capacities, thereby entitling them to a broader range ofopportunities and freedoms than ordinary humans. This prospect riskscreating the very kinds of oppressive hierarchical societies that thehuman rights tradition was designed to prevent, potentially paving theway for new forms of coercive eugenics and even the eventualextinction of the human species (Mehlman 2012; DeGrazia 2012).

Susan Levin (2021) offers perhaps the most systematic analysis andtrenchant critique of transhumanism in the literature to date. Shechallenges its core assumptions about the nature of the mind andbrain, its utilitarian commitments, its conception of liberaldemocracy, and its rather crude scientism. Drawing on scientific andphilosophical arguments to make her case, she contends that we shouldnot devote our limited scientific and technological resources to theenhancement project, which, she contends, is based on outdated andempirically unsupported assumptions about cognitive psychology,biology, and neuroscience.

6.3 Revisiting Eugenics

Just as it is metaphysically impossible to preserve our species fromfurther evolution, it is likewise impossible to control that process“from the inside out.” The genetic constitution of ourspecies is continually shaped by environmental forces of selectionthat lie beyond human abilities to control or even, as the phenomenonof emerging epidemics continues to illustrate, anticipate. Moreover,as disability-studies scholars observe, humanity is in no betterposition today to decide which human traits deserve promotion than itwas during the heyday of the eugenics movement, even if society werewilling to tolerate the reproductive policies required to manage eventhe human portion of evolutionary change (De Melo-Martin 2023).

The unsettling resemblance between the aspirations of earlyeugenicists and certain proposals advanced by contemporarytranshumanists, unfortunately, provides some evidence to support thisclaim (Sparrow 2011, Levin 2021). Such proposals often assume thatsome genotypes represent “jewels in the genome” (Sikela2006) while others constitute costly “toxic waste” to becleansed from the gene pool (Buchanan, Brock, Wikler, and Daniels2000). Critics argue that this way of thinking reduces persons totheir genotypes and undermines our commitment to moral equality amidbiological diversity (Asch and Block 2011).

However difficult these arguments may be to reconstruct, it isimportant to take seriously the concern that certain biomedicalinterventions may violate human nature, even in public discussions ofpolicy within a pluralistic society. Whether the concern involves thealteration of a constant of the human condition, like senescence; a“species altering” threat to our collective gene pool; orthe corruption of practices designed to celebrate the inherited humantraits we value most, these appeals all signal that the interventionin question has deep implications for who we want to become in lightof who we have been.

Respecting what we have, or have not, inherited from our parents doesnot, in itself, meet the need to decide which promises we want to maketo our children. Invocations of particular vulnerabilities, loyalties,or forms of sociality drawn from the past can provide fodder forpositive visions of human nature to guide those promises. Yet incommunities that recognize a pluralism of such visions, these appealsshould also prompt another policy-making response: the obligation toprotect the interests of those excluded from prevailing ideals, evenwhile we debate their merits.

The natural human gene pool has no top, bottom, edge, or direction: itcannot be “used up”, “diverted”,“purified” or “polluted”. The reservoir ofhuman mutual respect, good will and tolerance for difference, however,seems perennially in danger of running dry. Those who emphasize thefragility of human nature and its need for protection should rememberthat not every aspect of our nature is admirable or worthpreserving.

7. Conclusion: Military Enhancements

We shall conclude with a brief case study that illustrates many of theethical considerations discussed throughout this entry. Although wehave differentiated various conceptual and ethical issues raised byenhancement, in practice these considerations are entangled to varyingdegrees. Reflecting on whether military forces should use enhancementtechnologies to achieve their goals engages with multiple dimensionsof the debate, including the treatment/enhancement distinction,questions of fairness, moral enhancement, authenticity, anddehumanization.

7.1 The Context of Military Enhancements

In recent years, the ethics of enhancement in military contexts hasattracted growing attention. Popular fascination with the topic ofsuper-soldiers is hardly new – dating back at least half a century toCaptain America comics, which themselves have inspiredphilosophical reflection on virtue ethics and character (White 2014).Outside of the lessons learned from pulp science fiction, there is alongstanding history of military attempts to biologically enhancesoldiers’ combat effectiveness and chances of survival. Thehistory of warfare itself can be viewed as a history of enhancingsoldiers (Puscas 2020).

Throughout this section, we use the terms ‘soldier’,‘warfighter’ and ‘military service-member’interchangeably, much to the chagrin of those who use these terms moreprecisely within military institutions. In the United States, forexample, the term ‘soldier’ refers specifically to membersof the Army, whereas in Europe it refers to all military personnel.Here, we are deploying these terms in a broad and inclusive sense.

Historical examples reveal the enduring tension between moral efficacyand moral restraint. Legend has it that Celtic warriors eschewed bodyarmor (and sometimes even clothing!) in battle, thinking that itdiminished the glory of a true victory. By contrast, medieval knightswore full suits of armor that emboldened them to charge into combat.Indigenous peoples of the Orinoco basin (in present-day Brazil andVenezuela) fought under the influence of hallucinogenic drugs thatplayed both ritual and psychological roles in combat, enhancingcourage and aggression (Puscas 2020). In modern times, pharmacologicalenhancement has been common: methamphetamine use was widespread duringWorld War II, and as many as 70 percent of U.S. soldiers in Vietnamreportedly used psychostimulants to boost endurance, strength, andcombat fatigue (Puscas 2020). Advances in vaccination and battlefieldmedicine have also served to enhance soldiers’ resilience andsurvival (Eagan 2020).

Contemporary and near-future military enhancement efforts, however,are more invasive than earlier technological or pharmacologicalmethods. The United States Defense Advanced Research Projects Agency(DARPA) has been explicit about its interest in using biomedicaltechnologies to augment soldiers’ physical and cognitivecapacities. In a 2016 press release, DARPA announced a program on“Boosting Synaptic Plasticity to Accelerate Learning,” notingthat “unlike many of DARPA’s previous neuroscience andneurotechnology endeavors,it will aim not just to restore lostfunction but to advance capabilities beyond normal levels.”(DARPA, 2016,our italics). Similarly, in 2017 DARPA invested$100 million in gene-editing research with the hope of enablingsoldiers to “run at super-human speeds, carry enormous weight,live off their fat stores, and go without sleep.” (Eagan2020)

These types of genetic and neurological enhancements, rather thanrobotic or drone technologies, are the subject of this discussion.While autonomous systems raise their own pressing ethical questions,we focus here on bodily enhancements of human soldiers, or what weshall callmilitary enhancements.

7.2 The Ethics of Military Enhancements

Military personnel operate within hierarchical institutions in whichindividual autonomy and genuinely informed consent are constrained.Soldiers often face institutional, social, or economic pressures toaccept enhancement interventions, effectively diminishing theirvoluntary consent (Mehlman, et al. 2013). Autonomy is further limitedin contexts where refusal of an enhancement risks career setbacks orloss of operational status (Lin, et al. 2013; Pfaff 2019). Beyondexplicit coercion, service members are embedded in a military ethosthat valorizes strength, sacrifice, and peak performance, making itdifficult to refuse enhancement even when participation appearsvoluntary. Voluntary consent in these contexts is limited not only byrank and command but also by internalized values and socializedexpectations to be the best warrior possible (Eagan 2020). Thispressure can be especially intense within elite units, where refusalof a biomedical enhancement may be perceived as a lack of commitmentor even as a liability to the team. These dynamics contribute to theemergence of a “performance caste” within the ranks(Chneiweiss 2012). Moreover, the military’s cultural framing ofthe body as “government-issued”, reflected both in loreand in disciplinary actions such as treating sunburn as the“destruction of government property”, further underminesbodily autonomy and complicates ethical assessments of consent. Evenin the absence of overt coercion, the structural, cultural, andpsychological dimensions of military life render true informed consenthighly suspect in enhancement contexts.

Military enhancements also pose risks and side effects that may occurduring active service or long after discharge. Commonly used cognitiveenhancements, e.g., modafinil or psychostimulants, can impairjudgment, impulse control, and long-term psychological health (Lin, etal. 2012) The neurological enhancements suggested by DARPA may poseunknown and potentially irreversible harms on soldiers. These concernssupport arguments that military institutions have a duty of care toprotect soldiers from foreseeable biomedical risks (Moreno 2012).

Military enhancements raise special concerns about fairness, bothwithin and between military forces. These concerns may arise betweenenhanced and unenhanced soldiers within the same military institutionsor between military institutions, e.g., between one nation that hasenhanced soldiers and another nation that does not. Within a singlemilitary organization, unequal access to enhancement technologies maycreate unjust advantages for enhanced personnel (Lin, et al. 2013).Enhanced soldiers might also face greater operational demands, such asincreased deployment tempo, leading to higher rates of trauma andfatigue. Additional fairness issues arise from prospective geneticscreening in recruitment, which could exclude individuals based onperceived disadvantage, reinforcing inequalities of “the geneticlottery” (Lázaro-Muñoz, G., and E. Juengst,2015). Beyond the service period, enhanced soldiers may face uniquechallenges reintegrating into civilian life. While non-enhancedveterans already confront difficulties transitioning to civiliansociety (Shay 2011), reintegration may be especially complex for thosewho are genetically, neurologically or robotically enhanced (Eagan2022; Eagan and Moseley 2025). Traditionally, soldiers are standardlyrequired to return their government-issued firearms and gear upondischarge. How could they, and should they, return their enhancedbrains or robotic limbs? The question of post-service ownership raisesnew concerns about bodily integrity, medical autonomy, and thepotential for the continued state authority over persons’bodies. If military institutions retain control over enhancements,dis-enhancement may be required at discharge: a practice that mayinflict medical and psychological harm.

Military enhancements, especially pharmacological ones, also presentdual-use risks, which raise broader ethical concerns about unintendedoutcomes on civilians. Technologies developed for combat applicationscould be adapted by non-military forces for coercive purposes, e.g.,interrogation (Moreno 2012). On an international scale, thedeployment of enhanced soldiers by one nation could trigger anenhancement arms race, destabilizing norms governing permissiblewarfare (DCDC, 2020; Mehlman, et al. 2013).

Military enhancements that alter cognition or emotion could disruptthe moral responsibility of soldiers who make decisions in combat.Cognitive enhancements can alter judgment and decision-makingcapacity, which may complicate attributions of moral responsibility inwarfare (Levy 2007). Intuitively, we are aware that people who stayawake too long have diminished decision-making capacity. Soldiers whohave been enhanced to stay awake for vastly longer than normal periodsmay thereby experience impaired decision-making capacities. AsWolfendale (2008) argues, military personnel need to be morallyresponsible agents and moral responsibility is necessary for integrityand the moral emotions of guilt and remorse, which are central tomoral growth and psychological well-being. She contends that militaryenhancements that diminish soldiers’ capacity to experiencethese emotions would undermine the moral standing of the military andharm the well-being of warfighters. Relatedly, military enhancementsthat alter mood, memory, or empathy raise concerns about their impacton personal identity, personality and authenticity. Some argue thatheavily enhanced soldiers may no longer be the same persons afterreceiving the enhancements (Moreno 2012), or that the enhancements maylead soldiers to doubt whether their achievements and actions aregenuinely their own (Mehlman, et al. 2013). Addressing such questionsrequires greater conceptual precision in distinguishing amongphilosophical notions of identity, selfhood, and authenticity, asdiscussed earlier in this entry.

Finally, like the treatment/enhancement distinction in medicine,military enhancements face a slippery conceptual distinction withimportant ethical consequences. Traditionally, the Just War theoriesthat undergird military ethics have eschewed the use ofdisproportionately destructive offensive innovations, from crossbowsin the medieval period to carpet bombing and chemical weapons inmodern warfare, while generally accepting defensive innovations suchas stronger armor and more effective anti-missile systems. How, then,should we assess a project like DARPA’s PREPARE (PRemptiveExpression of Protective Alleles and Response Elements) [OtherInternet Resources], which seeks to develop gene-editing interventionsto confer soldiers with resistance to radiation and chemical agentsbeyond the normal human range? These innovations would be enhancementsby most criteria and raise many of the moral and philosophical issuessurveyed throughout this entry.

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Acknowledgments

We would like to thank Allen Buchanan, Jennifer Hawkins, JonathanShear, Robert Sparrow, and Michael Tennison for helpful suggestions,and Warren Whipple for valuable research assistance on the originalentry. For the most recent revision, we would like to thank SheenaEagan, Joshua May and Katrina Sifferd for valuable suggestions.