I. Introduction

Dictionaries commonly define the word "enhancement" as an increase or improvement in quality, value, desirability or attractiveness. In the broadest sense, the bioethical debate on enhancement concerns the question of how the use of means to improve various human characteristics and abilities should be ethically assessed. Whether a measure falls under enhancement depends on the definition of enhancement used in each case. 

The definitions differ in their basic assumptions. One thing they have in common, however, is that biotechnological means are used for enhancement. If, on the other hand, the more general question of the normative boundaries within which human striving for optimization should take place at all is the guiding principle when dealing with the concept of enhancement, then there is no reason to restrict consideration to medical-technical improvement strategies. According to this understanding, education and training programs, meditation exercises, adherence to good sleeping and eating habits or even the consumption of stimulants such as coffee, tea, or alcohol (so-called lifestyle drugs) can also be regarded as enhancement.

According to a widespread definition, enhancement is differentiated from medical or therapeutic measures, although it is not always possible to draw a clear line between the two. According to this understanding, the improvements sought by medicine always serve to combat generally recognized deficiencies such as illnesses or disabilities, whereas enhancement is aimed at the "mere" optimization of human characteristics. However, enhancement measures do not fall outside the traditional scope of medicine simply because they are non-therapeutic improvements to healthy people. Typical preventive measures such as vaccinations are also aimed at healthy people and attempt to improve them by reducing their susceptibility to certain diseases. However, the area of enhancement can be distinguished from the areas of prevention and therapy, which are unquestionably part of medicine, by pointing out that the latter, in contrast to the former, are related to disease.

Therapeutic, preventive or enhancement interventions raise ethical questions. The normative relevance already applies to the distinction between therapeutic and preventive interventions on the one hand and enhancement measures on the other. This is usually justified on the grounds that health, in the sense of the absence of illness and disability, is a fundamental good in which both the individual and society have an equal interest. In the case of enhancement, however, it is necessary to discuss which types of improvements that go beyond therapeutic purposes might not also be of interest to society. Critics of the distinction between medical interventions on the one hand and enhancement measures on the other point out that this distinction is just as blurred as the concept of disease itself. In fact, there is still no generally accepted view in medicine as to how pathological conditions can be distinguished from healthy ones. Within the enhancement debate, various strategies are being pursued to overcome the theoretical challenge posed by the controversy about the concept of disease.

Another way of categorizing enhancement measures can be made in terms of the properties or functions they aim to improve. Regarding the target functions, the following four important areas of enhancement can be distinguished:

  1. enhancement of physical performance (doping in recreational and competitive sports),
  2. enhancement of external appearance (aesthetic medicine)
  3. enhancement of cognitive abilities or emotional states (neuroenhancement)
  4. enhancement by means of genetic methods (genetic enhancement

While the improvement of cognitive characteristics (3.) is often referred to in the popular media as "brain doping", the term "neuroenhancement" has become established in the bioethical debate. Enhancement using genetic engineering methods (4.) can theoretically target the first three functions mentioned. If the human genome is one day fully understood and it is possible to draw the safest possible conclusion from a genotype to a phenotype, both external characteristics and tendencies for mental characteristics could be altered or determined by genetic intervention.

Not all objectives of enhancement can be covered by the four categories mentioned. For example, efforts to slow down or completely stop human ageing form a special area. Anti-ageing measures affect target functions from all the areas mentioned above, because the aim is not only to grow older in a healthy way, but also to look good and stay mentally fit for as long as possible. Another special case is that of moral enhancement, which refers to attempts to improve people's moral behaviour.

II. Ethical Aspects

Ethical considerations for evaluating the areas and methods of enhancement often begin with the associated but still partly unresolved questions of health risks and side effects. However, further ethical considerations are often based on the assumption that the circumstances in which a person decides to undergo enhancement are subject to certain ideal conditions: Efficacy and proven safety of the intervention as well as absolute voluntariness. In the following, reference is made to the most frequently discussed ethical debates. First of all, general questions of distinction between naturalness and unnaturalness are dealt with (1.). Subsequently, questions about the safety of enhancement are addressed and distinguished from disease, particularly in relation to challenges to medical ethics (2.). It then discusses the possibility of threats to justice (3.) as well as to personal identity and personality (4.), which finally address issues of autonomy and authenticity (5.).

1. Enhancement against nature?

Especially futuristic enhancement scenarios involving, for example, performance optimization through genetic interventions, such as the introduction of animal genes into the human genome or the acquisition of completely new abilities by coupling the human body with technical systems, are often met with the reservation that the interventions in question are unnatural or in any case violate human nature. "Naturalness" arguments against enhancement in general or against certain forms are fraught with two major difficulties. On the one hand, there is no consensus on how to define human nature or nature as such more precisely in conceptual terms. On the other hand, the question arises as to why humans should recognize nature as a guideline or boundary to their actions. 

A common conception of nature is determined in opposition to the concept of culture: While culture refers to what has been created by humans or "artificially" changed by them, nature, according to this understanding, stands for everything that exists independently of humans or is unaffected by them. On this basis, it is possible to use various phenomena to distinguish natural from artificial or culture-related aspects. From an ethical point of view, however, the juxtaposition of nature and culture alone does not provide a plausible justification for interpreting nature as something fundamentally worth preserving. Rather, humans seem to be in an elementary conflict with nature, as they can only survive by intervening in nature. Neither are cultural products such as Bach cantatas or mathematical evidence negative "per se", nor are natural phenomena always to be assessed positively, as demonstrated by volcanic eruptions or epidemics. Consequently, against the background of this definition of the concept of nature, enhancement measures need not be regarded as problematic simply because they are unnatural in this sense. 

According to a second popular interpretation, the nature of a thing represents its "essence". This interpretation is relevant when enhancement is considered incompatible with human nature. However, it seems ill-suited to validate a general suspicion of human improvement efforts, as most positions of philosophical anthropology agree that it is an important trait of humans not to be satisfied with their inadequate natural endowment, but to supplement or perfect it with technical and other cultural advances. Nevertheless, the objection that individual techniques or objectives of enhancement are contrary to human nature seems justified. For example, some of the many bioethicists who consider interventions in the human germline to be fundamentally unacceptable point out that this would permanently change human nature in terms of its gene pool. What speaks against this, however, is that even when attempting to explicate human nature through the genetic stock of the biological species Homo sapiens, the natural change in genetic make-up resulting from evolution must be taken into account. Against this background, it is not particularly plausible to regard artificial interventions in the human genome as fundamentally ethically questionable. If, on the other hand, one merely demands that only those genetic manipulations should be avoided which would create individuals who could no longer be considered members of the species Homo sapiens in the sense of the biological concept of species, this restriction would only affect extreme forms of genetic enhancement. 

An additional problem of naturalness arguments is that they discredit the processes in question as such, and not only their applications for enhancement purposes. This can cause uncertainty or even discrimination for people who benefit from the procedures in question. For instance, if it is deemed unacceptable to enable people to control technical systems through the power of thought by developing suitable interfaces between brains and machines, this would not only apply to cyborgs with superhuman abilities, but also to people who could use such interfaces to compensate for any disabilities. 

Even if one does not consider it convincing for the conceptual and normative reasons mentioned above to flatly reject enhancement procedures because of their unnaturalness or artificiality, one can still refer to the concept of nature in a weak sense. For example, in line with the slogan "nature knows best", some bioethicists argue that special caution is required whenever natural boundaries are crossed.

2. Enhancement as a challenge to medical ethics and possible addiction potential

If medicine in the traditional way is understood as a curative science, it can already be deduced from the literal meaning that doctors intervene in order to restore health, i.e. mainly in case of illness. In addition to this view, a "positive", i.e. not deficit-oriented, understanding of medicine as a science that deals with the conditions of health and the ways to promote, preserve and restore it has recently become established. This reinterpretation remains vague if health itself is only understood negatively as the absence of illness. However, there have been a number of attempts to give the concept of health a positive connotation. Particularly prominent, although admittedly not uncontroversial because of its ambitious claim, is the definition by the World Health Organization (WHO), which defines health in its 1948 constitution as "a state of complete physical, mental and social well-being and not merely the absence of disease or infirmity". If this view of health were to prevail among doctors, with the resulting definition of the field of medicine, enhancement measures should no longer appear to them to be "outside the profession", at least if such measures contribute to the promotion of well-being. 

However, doctors experience enhancement measures as a challenge to their professional self-image not only because they question a traditionally disease-based view of medicine. Another concern is that the increasing importance of such measures within the range of medical services could further fuel the trend towards the commercialization of medicine, which is already perceived by many as problematic. Doctors, like currently aesthetic surgeons or sports physicians involved in doping, are worried that they will be suspected of being more interested in their own profits than in the well-being of their patients or clients. This could lead to a loss of trust in the doctor-patient relationship. 

There are also difficulties regarding the distinction between disease and enhancement and the prescription of drugs initially indicated for therapeutic use as an enhancement for healthy individuals. This is problematic not only with regard to potential drug dependence, but also because there are no long-term studies on the use of drugs in so-called "off-label use", i.e. use outside the original purpose and approval. This gives rise to concerns that the prevalence of drug dependence could increase significantly if more and more people were to take medication to optimize certain traits without any medical reason. 

Pharmaceutical preparations that regularly cause dependence can be made subject to the Narcotics Act (BtMG) in Germany. Since the right of personality includes a right to self-endangerment, the classification of substances as narcotics is not primarily concerned with protecting consumers from dependence. In order to justify legal control of the use of certain substances, reference is made to the socially harmful consequences of addictions, which in the case of common illegal drugs manifest, for example, in the form of drug-related crime, incapacity to work and also as consequential health problems. Whether the permanent and regular use of pharmaceutical preparations for enhancement purposes results in comparable disadvantages for the general public is unclear. However, due to the lack of long-term studies, the approval and implementation of which is highly problematic because of the principle of non-harm to others, it is not possible to foresee to what extent such use could also entail adverse health effects.

3. Enhancement as a threat to equality

Enhancement may pose a threat to equality not only with regard to the question of the reasonableness of the preparations and methods, but also with regard to questions of social distributive justice and the associated social pressure. 

It can therefore be considered unjust in several ways if individuals gain advantages over others through the use of enhancement measures. For example, ensuring fair competition is at the heart of the fight against doping in competitive sports. The mere fear of no longer being competitive because other competitors may resort to prohibited performance-enhancing substances can be a strong motivation for the use of enhancement methods. It should be noted that athletes are under similar pressure when they know that their competitors are using authorized training facilities, materials or equipment that are not available to them (e.g. altitude training). As in the case of doping, it is also of concern when students try to improve their exam performance with illegally obtained prescription drugs, even if the use of such drugs is not explicitly prohibited in the relevant examination regulations. The reason for the concern is that it is clearly unacceptable to expect the other exam participants to also illegally acquire neuroenhancement drugs with uncertain efficacy and sometimes considerable side effects, in order to maintain an equal footing with the cognitively enhanced candidates. The associated question of the reasonableness of enhancement interventions or the consumption of neuroenhancement drugs would have to be reassessed if some of them were to be considered safe enough to be approved for use in healthy adolescents or young adults. However, even if it were permitted to take neuroenhancement drugs without a medical reason, their use would probably not be open to everyone because not everyone would be able to afford them. Therefore, even in a scenario with a legally available neuroenhancement drug with few side effects, it remains questionable whether it is unjust if wealthy individuals or groups of people gain further competitive advantages over less privileged ones by taking expensive psychotropic drugs. 

With regard to the question of what type and extent of social pressure is considered acceptable, it should be noted that the answer varies greatly for different areas of competition in society. In reality, there is extremely high competitive pressure wherever very special skills and qualities are decisive in determining suitability for coveted social positions. For instance, anyone aspiring to a career as a television presenter faces high expectations regarding their external appearance. Some consider it reasonable that applicants in this field should be able to remain competitive by investing considerable time and money in cosmetic procedures and physical training. Particularly in light of the health risks associated with such procedures, it appears problematic when applicants additionally optimize their appearance with aesthetic surgery. Even if the use of such methods is legal, it is ethically dubious when, as a consequence, others are pressured into potentially endangering their health by using such methods as well. When evaluating these and other competitive situations, it is also important to take into account the level at which the pressure to use such measures arises: at the level of the individual, society, or the state. 

When it comes to questions of equality with regard to the reasonableness of interventions and the use of enhancement preparations, those with a liberal attitude towards the use of enhancement measures like to counter them by pointing out that our society also finds it acceptable when parents pay for private tutoring for their children or when television presenters change their appearance through privately financed aesthetic surgery. The answer to this argument could again be that possible future inequities should not be justified by referring to currently de facto accepted inequities. 

Concerns about the possible exacerbation of existing social inequities through the widespread use of enhancement measures arise primarily when not everyone has access to these measures. The state could therefore counter these concerns by guaranteeing free access to certain enhancements. Proponents of pharmaceutical neuroenhancement argue, for example, that subsidizing effective and safe neuroenhancement drugs in particular might be in the public interest in the future, because improved cognitive skills would help people in many positions to perform their service to society more efficiently. It could be replied that it would be a waste to use limited public funds to optimize the mental abilities of healthy people whilst optimal care for sick people is not guaranteed. 

Whether the widespread use of a particular enhancement method will promote unfair social conditions is difficult to predict with certainty, given the many factors influencing the development of such conditions. However, there are already certain prohibited lists that severely restrict the unfair use of enhancement preparations. Fairness is particularly important in sports competitions, so it is not surprising that the inclusion of a product on the anti-doping organizations' prohibited list is already legitimate when its use could potentially lead to distortion of competition. It would be more difficult to justify such preventive bans in relation to potential enhancement procedures in other areas of society that are not so consistently oriented towards egalitarian ideals. After all, every ban means a restriction of individual freedom, which is easier to legitimize in the protected competitive area of sports than in everyday competitive situations. The potential unfair consequences of new enhancement methods are not only uncertain, but must also be weighed against potential individual and social benefits. For these reasons, many bioethicists are of the opinion that aspects of fairness justify a policy of state supervision and control over the development and application of such procedures, rather than outright prohibitions. 

The question of whether enhancement measures should even be required in order to be able to occupy certain social positions also depends on the available alternatives. One example would be a neuroenhancement preparation with few side effects that could significantly reduce the error rate of surgeons or air traffic controllers. In other areas, too, enhancement could certainly save costs and thus reduce the burden on the health care system. If genetic enhancement was able to reduce the expression of undesirable traits such as aggressiveness or strengthen mental stability, potential follow-up costs could be prevented. With regard to the question of the acceptability of social pressure, an air traffic controller or surgeon who does not want to bow to the social expectation of minimizing their error rate by using an approved neuroenhancement drug would still be able to choose from enough other satisfying fields of activity. A highly problematic development would be conceivable, on the other hand, if the consumption of potent neuroenhancement drugs beyond specific occupations became common practice among broad sections of the population. This could lead to a dramatic increase in the demands placed on certain cognitive skills, so that non-enhanced individuals would only be given the undemanding social tasks. The possible benefits to society that might result from an increase in the average mental capacity of the population would then have to be weighed against the risk of the emergence of a two-tier society with a non-enhanced underclass. 

In general, however, social pressure tells us nothing about its ethical acceptability. Just as in the case of concerns about the distributive justice of social opportunities, the normative assessment of potential social pressure toward enhancement is dependent on criteria of reasonableness. Use of a particular enhancement measure appears to be all the more unreasonable the higher the associated risks are on the one hand and the financial and personal costs are on the other. Furthermore, for both problem areas, what constitutes a reasonable level of inequality or social pressure can only be determined more precisely when compared to similar social conflicts.

4. Changes in personal identity and personality

Neuroenhancement in particular is occasionally seen by critics as a threat to personal identity, e.g. in the context of the debate surrounding deep brain stimulation or various non-invasive stimulation methods. Generally, this concerns the fear that the user of a particular enhancement method might change so fundamentally that the person in question could no longer be considered to be the same person they were before using the method. To avoid misunderstandings, it is useful to distinguish between a weak sense and a strong sense in which a person's identity may be affected. The weak sense describes character changes, which can also include so-called "identity crises". Accordingly, it is feared that the fundamental characteristics of a person will change more or less profoundly, which may lead to doubts about their own identity, both for themselves and for others. Even if such changes can be experienced as a crisis, the identity of a person does not usually disintegrate in the course of these changes to such an extent that one is faced with a completely new person in the end. If, on the other hand, a change is so radical that the original person seems to be replaced by a completely different person, this can be called a major change in personal identity. Not every definition of personhood leaves theoretical room for this extreme variant of a change of personal identity. If this possibility is considered, bioethical literature usually speaks of identity being affected in a numerical sense

The changes in personal identity anticipated by critics of enhancement are usually seen solely as a threat. This purely negative view is only appropriate when personal identity in a strong sense is at stake. However, the psychological consequences of enhancement are unlikely to ever be so dramatic that it might seem plausible to question the continued existence of the original person. It is likely that any changes that may affect individuals in the course of using enhancement procedures will only affect identity in the weak sense. Such effects can also occur as side effects beyond neuroenhancement, for example when doping with anabolic steroids leads to increased aggressiveness in competitive athletes. Although this is an example of a personality change through enhancement, which may be undesirable in most contexts, personal identity in the weak sense can also fundamentally change for the better: For example, if someone succeeds in overcoming (non-pathological) shyness by taking a (not therapeutically indicated) antidepressant, this could be considered a positive personality change through neuroenhancement. The personality could indirectly change even more, if, for example, the person's self-esteem or self-satisfaction were to increase significantly due to reduced social inhibitions. 

Both of the concepts of personal identity distinguished here can be useful for the ethics of enhancement. In conjunction with a suitably formulated concept of personhood, the concept of a major change in personal identity can serve to demarcate an area of unacceptable psychological consequences of enhancement measures. The practical relevance of this demarcation is rather low because it involves such radical breaks in the mental continuity of persons that any intervention that would threaten the personal identity in this sense would most likely be considered impermissible as a potential enhancement procedure. In contrast, the weak sense of personal identity has shown to be useful when trying to make a differentiated assessment of the psychological consequences of enhancement procedures, because it allows the distinction of both particularly relevant negative and positive effects. It seems obvious to fall back on conceptual resources of psychological personality theories when describing these effects, because the concept of personality offers the possibility to distinguish only temporary and peripheral psychological effects from those which, due to their relative stability and centrality, are decisive for the individuality or weak sense of identity of a person. In addition to conceptual criteria for describing personality changes, normative criteria are therefore also required in order to evaluate them from an ethical perspective.

5. Threats to autonomy and authenticity 

Occasionally, enhancement procedures meet with ethical reservations because they are seen as a threat to the self-determination or autonomy of their users. As already in the case of the concept of personal identity, it is also helpful with regard to the concept of autonomy to first draw a fundamental distinction. The concept of autonomy is used firstly to assign or deny persons the ability to self-determination in certain fundamental or "basic" respects. For example, the legal concepts of legal capacity, ability to give consent, ability to take legal action or even religious majority denote field-specific aspects of autonomy which people either have entirely or not at all at any given time. In order to be considered autonomous in the respective regard, persons must have different abilities in a form that meets certain minimum criteria, such as the ability to understand relevant contexts. Individual differences in these abilities that go beyond this do not play a role in the attribution of the respective self-determination ability. The application of the concept of autonomy follows a different logical structure if it is based on an ideal understanding of self-determination: Theories of ideal autonomy make it possible to evaluate courses of action, personality traits or even entire life or self-concepts as more or less self-determined, depending on how well they can be aligned with a certain ideal of self-determination.

Enhancements are primarily considered a threat to the ideal concept of self-determination. The loss of autonomy in a fundamental sense could at best be accepted as a serious side effect in desperate therapeutic decisions but would be impermissible as a consequence of an enhancement procedure. Autonomy-related concerns about enhancement should therefore generally not be understood as meaning that its users literally lose their free will since they no longer meet certain minimum requirements for autonomy. Rather, there is a fear of a gradual decline in individual skills that are relevant to self-determination in its various aspects. In this sense, concerns that enhancement procedures could lead to dependence, for example, call into question the autonomy of users, because addiction and dependence mean a partial loss of the capacity for self-control. The argument familiar from the discussion on aesthetic enhancement, namely that the clients of aesthetic surgeons are not really free in their decisions, but are externally influenced by social expectations and unrealistic beauty ideals, also refers to an ideal understanding of autonomy. 

A more precise assessment of concerns about the autonomy of users of enhancement requires a more detailed analysis of the respective understanding of ideal self-determination. A common definition of ideal autonomy is associated with the concept of authenticity. In the first instance, authenticity means the absence of self-alienation. In positive terms, the concept of authenticity is usually determined by reference to an "actual", "true" or "fundamental" self. One of the issues here is whether authenticity is integrated into the subjective perception of authenticity or whether there are criteria by which the authenticity of a person can be judged from the perspective of an independent observer. There is also considerable theoretical leeway with regard to the more precise definition of what constitutes a person's true self. The leading voices in the enhancement debate differ in particular on the question of whether the true self – understood as the practical identity that a person considers fundamental to themselves – is a given self that must be recognized in an act of self-discovery and then preserved, or whether it is rather the self freely chosen in an act of self-realization. The resulting notions of authenticity yield radically different evaluations of enhancement. Those who advocate the self-discovery model generally regard technical methods of self-optimization as influences that alienate their users from their given self. Proponents of the concept of self-realization, on the other hand, tend to welcome any support in the realization of personal self-development and therefore generally take a positive view of enhancement.

Suggested citation

German Reference Centre for Ethics in the Life Sciences (2024): In Focus: Enhancement. URL https://www.drze.de/en/research-publications/in-focus/enhancement [date of access]

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