The ethically significant difference between dual use and slippery slope arguments,in relation to CRISPR-Cas9: philosophical considerations and ethical challenges

Abstract

Biomedical research, on the one hand, contributes to important goals from generation of knowledge about the human body to the development and testing of therapeutics of all kinds. On the other hand, it can produce serious and sometimes unforeseeable consequences. In the ethical analysis of these two aspects of biomedical research, two important argumentative strategies play a major role. First, slippery slope arguments are used to warn of potential risks and to highlight knowledge-based limitations. Second, a dual-use problem describes the challenge that already established techniques can be used for both morally wrong and morally right purposes. These two argumentative strategies appear to share several similarities, which will be investigated in this article. For this purpose, the article will first provide clear working definitions for both types of argument. This lays the foundation for the further ethical analysis. In a second step, and in order to investigate the similarities and differences of the argumentative strategies with an example from current ethical debates, CRISPR-Cas9, a currently very promising tool of genome editing, will be examined. The extent to which the possible applications of this genome editing tool can be addressed by slippery slope arguments or the dual use problem will be investigated. For this purpose, selected studies involving the use of CRISPR-Cas9 will be examined. Based on this two-step, analytic and example-based comparison of slippery-slope argumentation and dual-use considerations, the article will detail the ethically relevant difference between the two argumentative strategies and at the same time contribute to the ongoing ethical debate about CRISPR-Cas9.

Introduction

Genome editing is perceived to not only serve therapeutic and preventative purposes in medicine, but also provide a means to absolute and competitive biological self-improvement or enhancement. While the absolute form is about the general improvement of the person or about being able to cope with the demands of life, the competitive form of enhancement refers to being better than others, for example in sport or the job market (Buchanan, 2009: 373–374; Heinrichs and Stake, 2018: 330–331; Rüther and Heinrichs, 2019: 165–166). From an ethical point of view, however, there are concerns about human freedom, equal access to such methods, and long-term consequences for society (Selgelid, 2009: 721–722). Slippery slope arguments and dual use problems are often at the center of this debate, because conceivable negative consequences become apparent (German Ethics Council, 2014: 87–89). The focus of this article is a philosophical analysis of these two argumentative strategies exemplified regarding CRISPR-Cas9. For this purpose, in a first step, slippery slope arguments and the problem of dual use are examined and transferred into precise working definitions. These definitions form the basis for the ethical analysis of the CRISPR method (Zhang et al., 2014: R40–R41). In a second step, it will become clear to what extent the possibilities of the CRISPR method can be interpreted in terms of a slippery slope argument or a dual use. For this purpose, studies already carried out will be analyzed, which promote awareness of the performance of CRISPR-Cas9. It will be shown that slippery slope arguments and dual use can be distinguished by time- and scope-specific differences, which are ethically significant.

Slippery slope arguments

Slippery slope arguments are mostly used to try to warn in argumentative form against serious consequences that were not intended by an original approach or technique. Often, the original goal is and was generally morally permissible, which cannot yet be said of innovations that have gone astray (Beauchamp and Childress, 2019: 186–187). It should be noted that some authors have emphasized the problematic nature of slippery slope arguments in terms of exaggerated and possibly paranoid predictions. However, this does not simultaneously prove their falsity; rather, their analysis requires a situation- and case-specific assessment (Enoch, 2001: 629–630; LaFollette, 2005: 481–483; Spielthenner, 2010: 149–150; van der Burg, 1992: 257–259; Volokh, 2003: 1028–1030). This type of argument is—in the context of research ethics—directed at researchers and other individuals directly or indirectly involved in a project, and structural specifications of a particular organization. All of them are supposed to refrain from the use of certain procedures or the use of a certain method because morally wrong or ethically unjustifiable consequences may result (Burgess, 1993: 169–170).

Such concerns seem to be particularly present regarding CRISPR-Cas9 due to its easy use and the fact that long-term consequences cannot be fully predicted. Although in most cases the basic research intentions are to minimize suffering, maintain health, or modulate diseases, other goals or applications cannot be ruled out (Fumagalli, 2020: 412–413). Adaptations of human genetics for warfare are conceivable, so that soldiers might become genetically resistant to hostile conditions and materials. Similarly, species improvement could be singled out as a goal by promoting certain genetic predispositions while preventing others (Jefferson, 2014: 675–676). Such approaches seem to be well captured by slippery slope arguments because the established use of these genetic scissors may lead to further permissive regulation. According to Burgess (1993), it is not uncommon to express fears that people’s moral compass will be negatively altered (pp. 169–170).

What is crucial is not only a potentially harmful use of these genetic scissors, but also the dissolution of all limitations brought about by established therapeutic use (Jefferson, 2014: 674–675). If CRISPR-Cas9 is allowed as a standard intervention for disease treatment via genetic manipulation, all embryos could prophylactically undergo genetic revision in vitro. According to Burgess (1993), such predictions can cause a stir precisely when societal expectations tend in a similar direction (pp. 170–171). Jefferson (2014) describes a slippery slope argument in terms of an “[. . .] empirical prediction, which warns of bad consequences if a certain course of action is taken.” (p. 672). It is important to note, however, that a distinction must be made between logical structure and empirical considerations. Empirical considerations describe certain political, social, and cultural understandings, which in a specific society also lead to specific ideas regarding the assessment of certain techniques, captured with slippery slope arguments (Fumagalli, 2020: 414–415; Jefferson, 2014: 678–679). The following illustration reflects a possible basic structure of slippery slope arguments (Jefferson, 2014: 672–673; Liga and Palmirani, 2020: 268–270; Walton, 2017: 1514–1515):

P1: Action X is generally morally permissible.

P2: Action Y is not generally morally permissible and causes apparently negative consequences.

P3: The execution of an action X leads to X₁, X_1+N and finally to Y.

P4: If an action X is permitted then action Y must also be permitted if, and then because, there is no morally relevant difference between the two actions.

C: Action Y must also be permitted.

The logical form of the argument seems to be valid, especially the deduction of the conclusion from the premises. Nevertheless, the focus on morally relevant differences in premise 4 seems to be essential. While this fact is emphasized by proponents and opponents of slippery slope arguments alike, it is dealt with in different ways. Jefferson (2014) points out that there can be controversial interpretations regarding what is morally permissible, if “[. . .] there is no distinct cut off point at which an action clearly stops being morally permissible [. . .]” (p. 673). The challenge of slippery slope arguments lies especially in the fact that while action X seems morally right in general, this cannot be said of action Y. By “general” it is meant that there are good reasons for accepting X, which are also supported by the associated social opinion (Burgess, 1993: 169–171; Volokh, 2003: 1033–1034; Walton, 2017: 1517–1518). In contrast, the claim that Y must be permitted given that X is permitted is (pace P2) not itself a claim of normative implication but a prediction of future change in moral (or legal) evaluation. And this prediction is qua empirical prediction uncertain. Thus, a slippery slope argument is not a matter of pure deduction, in that the conclusion necessarily follows from the premises. Only a moral equivalence of X and Y would turn it into a deductive argument, but P4 merely contains a prediction of equivalence in people’s moral opinion (Resnik et al., 2022: 3–5). Moreover, the clear identification of when exactly X and Y are to be considered morally equivalent seems to depend on subjective reasoning strategies and includes empirical assumptions (Jefferson, 2014: 673–674). Walton (2017) identifies precedents, a social acceptance, uncertainties regarding the difference between X and Y, and technological advances as key influencing factors and possible triggers for the acceptance of certain innovations (pp. 1518–1519).

Walton formulates three components of the slippery slope arguments that are consistent with previous considerations: X is the first step toward a feared consequence. It is followed by a loss of control with respect to the cutoff point described (Jefferson, 2014: 673–674), which he describes as a gray zone (Walton, 2017: 1513–1514). The consequence is catastrophic or particularly negative. On the one hand, the slippery slope argument is advocated by opponents of specific research by casting doubt on the first premise according to which X’s permission will lead to that of Y, too (Fumagalli, 2020: 414–415). On the other hand, proponents of CRISPR, for example, identify a morally relevant similarity between X and Y, according to which Y must be permitted if the moral acceptability of X is assumed. They point out that human genome modifications to somatic cells with CRISPR are allowed (X), provided they contribute to disease treatment. However, if such diseases could be prevented before birth by preparing the germ cells of (embryonic) fetuses appropriately with these genetic scissors (Y), this should also be allowed (Walton, 2017: 1519–1520). In both cases, the goal is to prevent disease and promote health. If X is allowed then Y must also be allowed, at least that is the logical conclusion.

A particularly critical point is that the general permission of X is not only decisive for our moral understanding of this action or of a technical achievement, but can also have an effect on the evaluation of Y (Jefferson, 2014: 674–675). Accordingly, a kind of habituation might occur over time, whereby the original moral dubiousness of Y is not denied, but a similar evaluative scheme becomes present with respect to Y because of the acceptance of X (Burgess, 1993: 171–172; Enoch, 2001: 645–646). In this sense, prior concerns about Y would fade in favor of (establishing) positive reasons for ethical acceptability, in part because X has become established as morally right. Jefferson (2014) rightly recognizes a conflict between moral values in the context of slippery slope arguments (pp. 674–675). Such arguments could lead to an unintended change in values or loss of values through an ill-considered approval of any research project—as in this case the arbitrary use of the CRISPR method. It seems questionable, however, whether this actually has to be the case. For Burgess (1993), too, such a moral decline would be relatively unlikely, because certain (bad) preconditions would have to be in place beforehand for this to happen (pp. 172–173).

According to Jefferson (2014), it seems quite justified to claim that “[. . .] moral decisions we make regarding A will affect our perception of the moral status of nearby cases.” (p. 677). Those considerations draw attention to possibly unconscious attitudes that may be obstructive to ethical judgment. Accordingly, it would be quite conceivable that the actual evaluation of a slippery slope argument does not concern X and Y, but focuses exclusively on X or Y, projecting the respective attitude onto the evaluation of the other action (premise or conclusion), so to speak (Corner et al., 2011: 147–149; Jefferson, 2014: 677–678; Liga and Palmirani, 2020: 272–274). Even if the previous explanations illustrate the potential susceptibility of slippery slope arguments to false conclusions and logical fallacies, this need not always be the case. What seems essential is a sensitive approach that is guided by ethical principles, moral values, and appreciates slippery slope arguments as a thoroughly plausible basis for discussion.

Dual use problem

A dual use problem exists whenever the results of research can be used both positively and negatively (Kosal et al., 2016: 9–10). There are research projects in this regard, which are of great concern and are summarized under the term Dual Use Research of Concern (DURC) (German Ethics Council, 2014: 14–16). Such research generates potentially negative consequences for the life, safety and health of humans, animals, or the environment. The National Science Advisory Board for Biosecurity (NSABB) definition is as follows:

Research that, based on current understanding, can be reasonably anticipated to provide knowledge, products, or technologies that could be directly misapplied by others to pose a threat to public health and safety, agricultural crops and other plants, animals, the environment, or materiel. (NSABB, 2007: 17).

This formulation is also implemented very similarly in the statement of the US Government on dual use research from 2014. In addition, reference is made to potentially usable information, a more serious extent is assumed and the threat to national security is included (United States Government, 2014: 3). Selgelid (2009) also refers to this currently increasing risk of potential misuse because “[. . .] information about how to produce biological weapons is readily available in published scientific literature.” (p. 720). According to Miller and Selgelid, a dilemma arises because, on the one hand, progress in biomedicine, for example, appears to be indispensable for the continued existence of the human community, but this constant pushing of technical innovations can also be misused and, above all, used in a harmful way (Miller and Selgelid, 2007: 524–526; NSABB, 2007: 7–8). Researchers involved in a project are to some extent caught in a dilemma between desired research goals and the effort to avoid risks (Baumann, 2016: 145–146). Especially in the biomedical sector, there is a tension between biosecurity and bioterrorism, which is why Selgelid (2009) warns against the careless publication of research results (p. 721). As a result of these considerations, there is a challenge to approach technological progress with openness and simultaneous caution. For an elaborate understanding, Miller and Selgelid (2007) suggest a conceptual clarification for dual use (pp. 526–527):

goals: good or bad / military or non-military / offensive or defensive.

users: original (primary) users with intended use / (secondary) users who have different goals than originally intended.

use: either an actual or imagined (positive or negative) use.

consequences: intended consequences / unintended but foreseen consequences / unanticipated but foreseeable consequences.

Based on this distinction, individual projects are easier to evaluate in terms of misdirection or carelessly accepted consequences (Miller and Selgelid, 2007: 527–529). To counter the negative aims of dual use research, many suggestions have been made for years. The WHO offers numerous publications, meeting documentations, and general information on its own website (World Health Organization, 2023). In a publication from 2007, the National Science Advisory Board for Biosecurity created an orientation guide (NSABB, 2007: 1–3) for dealing with dual use goods and research results. This elaboration is aimed at researchers, institutions, their supervisory bodies, and policy makers (NSABB, 2007: 11–14). Mahfoud et al. (2018) argue for the differentiation and refinement of existing guidance and orientation documents, due to the ever-changing circumstances within science (pp. 76–78). However, Rath et al. (2014) make clear that there are many concepts of what dual use really means (pp. 770–771).

Although the term “dual use good” very often refers to microorganisms (Rath et al., 2014: 778–780), the inclusion of CRISPR-Cas9 in this horizon seems to be justified. On the one hand, microorganisms such as viruses can be adapted with this gene editing system and the functioning of individual genes can be better understood (Ehni, 2008: 147–148; German Ethics Council, 2014: 30–32). On the other hand, the handling is relatively simple, which makes the morally wrong use of any person or organization seem particularly realistic. The NSAAB categories support this impression, as CRISPR can, for example, enhance the harmful consequences of a biological agent or compound (NSABB, 2007: 18), circumvent certain immunities (NSABB, 2007: 19), or co-design new pathogens, for example (NSABB, 2007: 21–22). The designation of CRISPR as a dual use good refers to the method itself, respectively the applicability as gene scissors, which can be derived from scientific research results.

While within biomedical laboratories and institutions research is mostly meant to be positive, in the context of DURC, handling and consequences are conceivable which are contrary to the general claim of minimizing suffering and restoring health (Frankel, 2012: 1523–1524; United States Government, 2014: 3–4). The use of genome editing—in this regard, Kosal emphasizes the simplicity of CRISPR-Cas9—would then not pursue the treatment of diseases through genetic modifications, but rather certain objectives that are considered morally wrong or ethically unjustifiable (Kosal et al., 2016: 9–10; Mahfoud et al., 2018: 74–75). The German Ethics Council emphasizes the importance of the CRISPR method and related information as a challenge for dual use: advances in microbiology in recent years, for example, have helped to equip viral vectors with dedicated genes, which then express certain proteins and consequently release bioactive substances (German Ethics Council, 2014: 42–44). These bioactive substances can not only be functionally studied, but equally circulated with a harmful intent. Targeted manipulations of the genome are relatively easy to implement, at least in theory, with the gene editing system discussed. Based on the previous considerations, the following logical structure of dual use is proposed for further investigation:

P1: A dual use good can be used both positively and negatively.

P2: The positive and negative use does not refer to hypothetically conceivable development possibilities (time).

P3: The positive and negative use does not refer to arbitrary extensions of the area of application (scope).

P4: If CRISPR-Cas9 is a dual use good, then it fulfills these (P1-P3) criteria.

C: CRISPR-Cas9 allows positive and negative use at specific times and in a possible scope of application.

The precise explanation of these assumptions is provided in the following passages. Nevertheless, it should already be noted here that this argumentative strategy can not only make dual use easier to understand, but also makes it possible to differentiate it from slippery slope arguments based on time- and scope-related considerations. An ethical dilemma arises predominantly because increased research effort seems justified and necessary for numerous reasons (promoting health, minimizing suffering, increasing knowledge), but this also fosters potential misuse (Ehni, 2008: 150–151; Marris et al., 2014: 396–397; United States Government, 2014: 6–8). Dual use does not generally denote a dangerous future scenario, through the further development of already established methods, techniques, or goods, as is the case with the slippery slope arguments presented above. What is central is the performance of the respective good addressed and thus current or currently conceivable morally wrong and morally right ways of use (NSABB, 2007: 17–18). From these considerations, it can be seen that dual use is associated with a potential for misuse of study results, for example. This potentially harmful and morally wrong applicability needs to be evaluated, which is done in the following passages by comparison with slippery slope arguments.

Differences and communalities of slippery slope and dual use arguments

While a dual use problem refers to the potential misuse of an experimental conclusion, research findings, or novel methods (such as CRISPR) at the present time and based on existing capacities, this is not the same for slippery slope arguments (NSABB, 2007: 22–24). For such arguments, hypothetical assumptions concerning a future possibility of application of the discussed research (or other goods) becomes decisive (Resnik et al., 2022: 6–8). There may be an assumption, plausible at first glance, that the CRISPR method, for example, by being included in the horizon of a dual use good, must automatically entail a slippery slope argument, especially if researchers or others use these research findings in morally wrong ways. However, this is not the case. Quite the opposite: a slippery slope argument presupposes a morally benign original use, but the dual use argument concedes that a given research result has at least one non-benign present use. It is precisely through a morally problematic, that is, dual use of CRISPR-Cas9 that the construction of a slippery slope argument is undermined. If one assumes that the already described production of in vitro embryos with specific adaptations to spread diseases in the population or to pursue military goals with them is morally wrong, this act X cannot be used as the starting point of a slippery slope argument (Liga and Palmirani, 2020: 269–271). In contrast, it could be argued that wrong use of CRISPR is about act Y because, according to Miller and Selgelid’s criteria, we may also be dealing with potential areas of use (Miller and Selgelid, 2007: 524–526). Here, however, the misuse of genetic scissors likewise leads to an abandonment of any plausible slippery slope argument, because Y must certainly have the potential to be considered ethically acceptable by a given society.

One might assume that dual use considerations regularly give rise to slippery slope arguments. This could be thought because if one assumes that for any given type of research incremental further investigation can transform them from purely benign to dual use results (Urbina et al., 2022: 190–191). If we are to accept the original research result as morally unproblematic and no incremental step makes a decisive moral difference, so the argument could go, we would have to accept the final dual use good as unproblematic too, which clearly is the wrong conclusion. This connection of dual use and slippery slope arguments does, however, not work because referring to purely prospective and theoretically conceivable areas of application will fail because, as already described, there is a timely significant discrepancy between dual use and slippery slope arguments. In this case, the potential performance of a dual use good cannot be used to describe the current capability (Liga and Palmirani, 2020: 274–276). Otherwise, for example, one would have to ban a DURC-irrelevant good A in principle because further research could also derive a harmful good A* from it—this would transform DURC into a slippery slope-like argument. Nevertheless, it should be noted that in practice it may seem difficult to assign a research good or a scientific result to action X that is completely unproblematic, that is, has no dual use potential. The decisive factor is the positive use of scientific results as action X in line with current acceptance, which is why the syllogism for this argumentation structure outlined above contains the formulation X is generally morally permissible.

Consideration of slippery slope arguments on the one hand requires a distinction between current performance (e.g. knockout genes, viral load reduction) as a mostly morally acceptable action X and, alongside this, foresight of potentially precarious actions Y that may arise as a result (prevention-selection, enhancement), which may have a negative impact on morality, humans, and the fellow world (Walton, 2017: 1517–1519). Consequently, time and scope-related aspects have to be integrated, which also make the ethical assessment hypothetical in a certain sense. On the other hand, the ethical evaluation of a dual use good, which applies to the CRISPR method on the basis of previous research, does not involve comparable speculation (Fumagalli, 2020: 416–417). It is crucial to examine already established techniques and associated misuse potential. Following the slippery slope arguments, this involves action X rather than action Y, which can sometimes only be imagined (Walton, 2017: 1527–1528). From an ethical perspective, it is important to keep the presented differences in mind.

Study examples

CRISPR technology enables both temporary and permanent changes to the human genome by introducing, adapting, or removing specific genes (Zhang et al., 2014: R43–R44). In the study by Kizner et al. (2020), iPS cells were manipulated with CRISPR-Cas9 in vitro to trace the influence of a specific gene on the development of mental disorders (pp. 616–617). In individuals with cognitive impairment, autism, schizophrenia, or bipolar disorder, scientific evidence suggests that a gene called KCTD13 has an undesirable effect. Its effect was suppressed with the help of a knockout gene. Other research results, for example by Wang et al. (2017) confirm the effect of knockout genes and their significance for intentional gene expression (pp. 9–11).

Within the study of He et al. (2018), CRISPR-Cas9 was tested for the potential treatment of ovarian cancer (pp. 223–224). In contrast to the scenario presented earlier, this application of genome editing was in vivo, but in a mouse model. The goal was to target a gene called DNMT1 in vitro and in vivo, which is associated with the development of ovarian cancer. According to the authors, the study presents a novel and promising antitumor therapeutic agent based on gene editing (He et al., 2018: 230). Similar success in terms of tumor tissue reduction is shown by the study results of Ju et al. (2022: 649–651).

Another option is to regulate DNA segments in vivo to influence the status or characteristics of cells (Wang et al., 2016: 236–238). In the study by Stone et al. (2020), chimeric tissue served as the basis for the application of gene editing system (pp. 258–259). In this study, mice infected with the hepatitis B virus were treated and, according to the authors, this approach represents, “[. . .] the most rigorous testing to date of anti-HBV gene editing in vivo [. . .]” (Stone et al., 2020: 266–268). However, the limited transferability of these results to humans should be noted. Comparable and yet-to-be-solved tasks are described by Papathanasiou et al. (2021) for genome editing in vivo (pp. 3–5).

Ethical analysis

What becomes apparent by looking at the three studies presented is that CRISPR-Cas9 can be applied in many ways, for example, to manipulate specific genes in vitro (1), to introduce them into a specific organism (2), or to edit specific DNA segments in vivo (3). While the objectives in these experiments are a better understanding of neuropsychiatric diseases, prevention of cancer, and viral infections, misuse of the genetic tool is easily imaginable. A dual use problem is possible mainly because not only the results of these genetic manipulations are freely available, but also the necessary procedure of the respective study is described in detail (Vinke et al., 2022: 37–39). Speaking somewhat hypothetically, it would be conceivable, for example, to deliberately produce human beings who do not carry the described knockout gene (1) in their genome, but rather the gene KCTD13 has been adapted or specially activated to force psychological obedience (German Ethics Council, 2014: 42–44). Similarly, it seems quite realistic to claim that knowledge of the relevance of DNMT1 (2) to carcinogenesis can also be used negatively, insofar as a desired gene expression is controlled in vivo with the CRISPR method (He et al., 2018: 229–231). Since viruses are dua use goods, it is obvious to use the presented positive adaptation of hepatitis B infected mice (3) also to specifically infect humans with a CRISPR-modified virus (DiEuliis and Giordano, 2018: 239–240).

Whether the results of the described studies can be regarded as a starting point for a slippery slope argument must be clarified independently of the potential dual use problem. If one recognizes the treatment of mental illness (1), measures for cancer therapy (2), or even the cure of viral infections (3) as desirable and ethically justified goals—because, for example, health is thereby promoted and suffering prevented—the integration of a knockout gene in vitro and in vivo, as action X, seems to be morally right (Jefferson, 2014: 673–674). The same seems to be true for the in vivo adaptation of viral segments of DNA, using CRISPR-Cas9. Now, allowing X would have to lead to also allowing what appears to be a particularly dramatic and morally wrong application of CRISR-Cas9, because people will become more likely to judge that there is a moral equivalence of X and Y based on social habituation (Walton, 2017: 1517–1518). Action Y—which is exemplified in the following section—is not currently morally permissible, but could become perceived so, which is considered a major threat. This highlights the differences in time and scope described above, because the focus is no longer on the current application possibilities, but on a hypothetical expansion.

With increasing research, it will be possible to associate more and more genes with specific diseases and to assign larger sections of DNA with customized templates (German Ethics Council, 2014: 39–41). Therefore it seems quite plausible to use CRISPR-Cas 9 to customize embryos in vitro to prevent possible diseases (Kizner et al., 2020: 622–624; Zhang et al., 2014: R42–R43). The actual implementation of such actions Y is currently only possible to a limited extent, although it is becoming increasingly likely due to numerous study results (Nahmad et al., 2022: 1807–1809). In addition, it is important to ask whether there are differences between the two actions X and Y in terms of a moral judgment. In both cases, the aim is the prevention of suffering, disease-related concomitants, and the promotion of healthy living. Nevertheless, X describes an experiment in vitro or in vivo and Y describes the possible development into an adult organism (Wang et al., 2017: 9–11). This opens up additional questions regarding informed consent, realistic feasibility of implementation, discrimination, or side effects for the pregnant woman (Baumann, 2016: 144–145).

The potential consequence of the possibly emerging moral acceptance of Y is, from an ethical perspective, by no means to be considered a terrible scenario. At present the majority of society would probably be critical of a general establishment of Y and, consequently, of the preventive treatment of any disease—through the adaptation of embryos in vitro and a subsequent IVF (in vitro fertilization). But looking at it more closely, this permissive policy seems to be primarily about the promotion of moral values (Selgelid, 2009: 721–722). These include health, which is intrinsically valuable and constitutive for the fulfillment of certain concepts of life (Marckmann, 2008: 888–889). Likewise, the prenatal prevention of diseases could contribute to more justice if all human beings were offered the same chances for a successful life.

On the other hand, a slippery slope argument concerning the same X but where Y is the intentional enhancement of performance or improvement of the human being (Walton, 2017: 1516–1517) would have to be evaluated completely different. In such—currently hypothetical—scenarios, the prevention of known diseases is no longer the shared intention between X and Y, but the latter’s objectives are to make human beings more robust, resilient, stronger, or more intelligent (Resnik et al., 2022: 6–8). The currently unforeseeable consequences of enhancement, a societal rejection, and the unrealistic nature of such assumptions, make a slippery slope argument concerning Y available.

Final considerations

The foregoing investigation makes clear that there is no necessary connection between dual use issues and potential slippery slope arguments. Just because a scientific achievement reveals the potential to be used for acceptable and unacceptable purposes, this by no means clarifies that arguments on the basis of morally problematic predictions can be made in a comprehensible way—and vice versa (Walton, 2017: 1521–1523). Applying this to the previously mentioned studies, the integration of a knockout gene, through genetic reengineering of iPS cells, would be construed as dual use if individuals have morally wrong intentions with this potential opportunity (Mahfoud et al., 2018: 76–78). For example, they could misuse this technique to switch off important regions of the human genome to cause disorders or diseases. In contrast, slippery slope arguments capture those considerations that are not limited to the integration of knockout genes, but predict certain risks that are potentially conceivable in the future as a result of the moral establishment of this technological achievement (Jefferson, 2014: 675–676). These involve, for example, the extension of individual gene adaptations to the entire human genome or the aforementioned in vitro preparation of human embryos (Foht, 2016: 12–14).

Here, it becomes apparent that, in terms of time, slippery slope arguments necessarily integrate future hypothetical applications, and the scope of application is significantly expanded. These two differences must also be brought to mind from an ethical perspective when classifying slippery slope arguments and dual use. It is of crucial relevance here to assess the risks of, for example, the gene editing system discussed at the present time and not to misuse potentially conceivable further developments, as a yardstick for the current analysis. Those considerations highlight the extent to which the misuse of CRISPR-Cas9 leads to the failure of any attempts to establish a sound slippery slope argument. The two ideas are mutually exclusive in this investigation, thus warranting special attention. Through the previous assessment of selected studies, ethical challenges associated with dual use aspects and potential slippery slope developments have been illustrated and distinguished. Thus, the analysis of CRISPR-Cas9 exemplifies the differences and (in)compatibilities between dual use and slippery slope issues in general.