2. The phenomena

On top of instrumentalization, there are, at least, two common types of mistreatment frequently suffered by migrants. These cannot be accounted for adequately by the FH as it stands.

3. The FH as it stands

Kant’s FH has two parts: ‘So act that you use humanity, whether in your own person or in the person of any other, [(i)] always at the same time as an end, [(ii)] never merely as a means’ (G, 4: 429.10–12).Footnote ¹²

On a standard reading, the FH’s first part, (i), is broad in scope, encompassing all treatment of persons. Certain forms of indifference and treating someone with unjustified hostilityFootnote ¹³ as well as instrumentalizing them are all failures to treat a person as an end. In this way, the FH as it stands can account for the phenomena we outlined in the previous section. However, there is also an important sense in which the FH, as it stands, cannot account for the phenomena. Additional categories are needed to account for the egregiousness of the wrongdoing, which makes the wrongdoing subject to a strict prohibition in analogy to the function of (ii).

If we want to single out mistreatment and egregious failures of treating others as ends and thus generate stringent duties, we need additional normative content. Standardly, this is seen as the function of (ii), the prohibition against treatment as a mere means. However, (ii) is narrow in scope: It pertains to one specific type of failure to treat as an end, namely, failing to treat someone as an end due to their instrumental value or, in other words, to instrumentalizing them.Footnote ¹⁴ Kant’s prime example for this is making a promise to pay back money with no intention of honouring the promise (G, 4: 429.29–430.9). By deceiving someone, I use them as a mere means, as a tool or instrument that has no say in the way it is treated and is made to serve my ends instead of their own ends.

There is a good philosophical rationale for the standard reading of the relation between (i) and (ii). For Kant, treating someone as an end in themselves can never justify treating someone as a mere means. We may never deceive or coerce anyone in order to serve our or someone else’s ends. Thus, the prohibitions that (ii) issues have to be more stringent than the general command expressed in (i). (ii) limits how we can live up to (i).

Some of the mistreatment presented in Section 2 strikes us as strictly impermissible without any latitude. On the standard reading of the relation between the two parts of the formula, (i) on its own only yields imperfect duties. By contrast, (ii) specifies or generates perfect duties, stringent prohibitions against certain courses of action.Footnote ¹⁵ Imperfect duties allow for latitude concerning instrumental questions, such as what the appropriate ways of treating others as ends in specific cases are (offering help in-person, donating time or resources to a charity, backing off and letting other people pursue their ends on their own). There may also be latitude with regard to how much one is required to do. Many Kantians think that we are free to do more or less to meet the requirement to treat others as ends in themselves, and that it is certainly a good thing to do more rather than less, but no strict or absolute prohibitions against certain types of action can be inferred from (i) alone.Footnote ¹⁶

In short, additional categories of mistreatment are needed because they can capture types of mistreatment that strike us intuitively as egregious, yet, they are not strictly prohibited via (i), and (ii), the prohibition against instrumentalization, cannot prohibit them because the mistreatment does not constitute instrumentalization.

One may object at this point that in (ii), Kant uses ‘mere means’ in a technical sense to simply refer to all violations of perfect duty. For instance, Japa Pallikkathayil (Reference Pallikkathayil2010) suggests that treating someone as a mere means should be understood as a violation of someone’s rights or of their equal standing.Footnote ¹⁷ In that case, (ii) should not be understood in a narrow sense as picking out a specific, impermissible, form of using someone as a means in the pursuit of one’s ends. We would therefore not need to introduce categories of mistreatment different from treating as a mere means. Such a reading of the FH may strike us as more economical or more elegant, as it preserves the symmetry between ends and means.

However, spelling out treating as a mere means as just any case of rights violation or violation of equal status or as a case of any other extremely broad reading of this concept is not in line with how we normally use ‘treating someone as a mere means’. In fact, the majority of Kant scholars maintain that treating as a mere means requires a specific relation to the person I mistreat. I must be treating this person as a means or as a tool to my ends and in such a way that it constitutes treatment as nothing but a means.Footnote ¹⁸ Moreover, as our examples in Section 2 hopefully already indicated and as we will explain further in the next sections, mistreating persons who are not of (perceived) instrumental value to oneself is different from instrumentalization in a number of ways. Explicitly distinguishing these forms of mistreatment would make for a better FH. We will revisit the question of whether ‘mere means’ should be understood as a technical term, as one of the objections we discuss in Section 7.

Whilst our approach to some extent trades off a certain form of simplicity and elegance against the ability to better account for important conceptual distinctions and nuances, we do think that the distinction between three different types of mistreatment is already present in Kant and has its own form of elegance if not simplicity. Kant maintains that ‘things’, as opposed to persons, can be accorded ‘only a relative worth’ (G, 4: 428.21).Footnote ¹⁹ An agent mistreats a person if the value the agent accords to this person is contingent on the agent’s own ends. Kant sometimes puts this point in terms of whether others function as ‘the limiting conditions of our actions’ (4: 449.32–3, see also 430.28–431.1, 431.7–8, 438.4–8). The FH ultimately requires that I treat persons within limits imposed by their unconditional value, not based on the value or disvalue this person has for my ends.

Mistreatment can take three different forms, corresponding to three possible types of relative worth: exploiting the person’s instrumental value if the person can serve the agent’s ends, being indifferent even to vital needs of a person if the person is neither useful nor a threat to the agent’s ends, and harming or disposing of the person if the person is of disvalue to the agent or her ends. There is thus a logic and symmetry to Kant’s original category and the two additional categories we propose in this article. Individuals can be mistreated because of their instrumental value (mere means), lack thereof (mere thing), or because they are perceived as of disvalue (mere threat). Since we can either positively value something, be indifferent towards it, or consider it as of disvalue, it seems that in conjunction these categories capture the most significant ways to mistreat persons.

We should bear in mind that the prohibition against treatment as a mere means is not one against treatment as means. Only reducing others to their instrumental value, treating them as a mere means, is prohibited. The same holds for other categories of mistreatment. We can treat others as things or threats as long as we do not reduce them to their perceived relative lack of instrumental value or to their perceived disvalue and treat them as a mere thing or mere threat.

We should also flag that it is not the case that treatment as a mere means has necessarily a devastating impact on victims. Treatment as a mere means can consist of forms of deception in which I am being swindled out of an amount of money I can easily afford to lose, and where it is clear that the deception was in no way personal. Likewise, other categories of mistreatment will capture distinct and significant forms of mistreatment, but not all cases of mistreatment that fall under these categories will be extreme in terms of impact on victims. For Kant what matters is not consequences, for victims or overall, but whether someone is treated in ways befitting a person.

Beyond the interpretation or defence of Kant’s ideas, there are also systematic reasons for developing the FH into a principle that acknowledges treatment as a mere means as only one form of mistreatment, amongst others. The work of sociologist Julia O’Connell Davidson (Reference O’Connell Davidson2016) shows that it is a mistake to conceive of instrumentalization or exploitation as the paradigmatic wrong suffered by migrants and to overemphasize its significance. Many migrants are not trafficked against their will into other countries. Rather, they migrate of their own volition. If they are subject to exploitative labour, then this is often because they lack legal access to countries of their choosing or lack the right to take up legal employment in these countries. In Kantian terms, they lack opportunities to be a means for others on their own terms (Mieth and Williams Reference Mieth and Williams2023). Migrants usually want to find a useful role in their host society. Such roles allow them to secure themselves against many forms of mistreatment and would also prove wrong alarmist rhetoric about supposed burdens and dangers they may pose. The positive moral status of persons as means (on their own terms) for others is a significant and underexplored one in the context of migration and other areas and is frequently sidelined by concerns about treatment as a mere means. Moreover, laws that ostensibly protect migrants against instrumentalization, such as the United Kingdom’s Modern Slavery Act, can be used against migrants, as the Act gives the police broad powers and a supposed justification to control borders more vigorously and to arrest migrants on suspicion of being traffickers or having hired traffickers. The category of mere means is particularly problematic in the context of migration and must be supplemented. It distorts the debate if treating it as a mere means is our only paradigm of mistreatment.

There are also blind spots in the extant Kantian debate about migration which parallel our concerns. The Kantian literature on migration focuses on the political and institutional level, on cosmopolitan law and right (Benhabib Reference Benhabib2004), as well as the right to be somewhere or to occupy a space on earth (Huber Reference Huber2017; Herman Reference Herman2021: 204) and on original common possession of the earth (Pinheiro Walla Reference Pinheiro Walla2016). The focus here is on legal rights and on what happens before migrants enter a host country. There is neither sufficient attention to the different ways in which migrants are mistreated before they enter a new society nor to their precarious moral status once they have entered a new society.Footnote ²⁰ Even when authors do pay attention to specific forms of mistreatment, such as Wyrębska-Đermanović (Reference Wyrębska-Đermanović, Horn and dos Santos2022), they typically only focus on one specific problem migrants face, such as involuntary statelessness. Generally, mistreatment that cannot be conceptualized by the FH as it stands constitutes a blind spot in Kantian debates.Footnote ²¹

4. Treating and regarding others

As we emphasized in our description of the phenomena in Section 2, migrants are often ascribed an inferior status in political and public discourse. If a group or individual is regarded as of lesser status, it is psychologically easier to mistreat them. If those in power as well as the public at large consider the lives of unaccompanied children from other countries as less valuable than the lives of British children, then this explains why no action was taken to find missing migrant children. How a mistreated person is regarded or considered by perpetrators is often pertinent to understanding the mistreatment suffered.

It is a question often glossed over in the literature what it is that the FH is to regulate. Strictly speaking, the FH demands that we ‘act’ so that we ‘use humanity’ in a person in certain ways. The standard interpretation is that this is about how we are to treat persons.Footnote ²² This interpretation has recently been challenged from two sides. On the one hand, Kleingeld (Reference Kleingeld2020) argues that we should understand the FH’s scope as narrower, referring only to how we use persons.Footnote ²³ On the other hand, there are ethicists who advocate a different and potentially wider scope. For instance, Audi (Reference Audi2016) thinks that the FH should regulate conduct, which may include action types, reasons or motivation, and the mode of treating (e.g. disrespectfully). Moreover, Derek Parfit (Reference Parfit2011: 232) thinks that the ‘important truth’ behind the Mere Means Principle is that ‘[i]t is wrong to regard anyone merely as a means’.

Particularly the proposal that the FH should extend to how we regard others is interesting. Kant himself sometimes phrases versions of the FH in terms of how rational beings must ‘always be regarded’ (G, 4: 428.11). Moreover, the examples we have presented often refer to how migrants are perceived or regarded. In some cases, mistreatment even aims to create a certain perception of them, such as that they are dangerous or that they are owed nothing. However, we do think that it would be a misunderstanding of the FH to maintain that it only aimed at regulating how we regard or consider others.Footnote ²⁴ We do think that the standard interpretation is right that the FH seeks to regulate treatment. Yet, to understand the moral status of how a person is treated, we will often have to think about what kind of underlying attitude or way of regarding someone underlies this treatment. This is particularly plausible on a Kantian framework, since for Kant moral judgements are not about individual act-tokens but maxims, which contain an agent’s ends.Footnote ²⁵ Indeed, maxims or acting on maxims is what the Formula of Universal law seeks to regulate (4: 421.7–9), and Kant maintains that all versions of the Categorical Imperative are formulae ‘of the selfsame law’ (4: 436.8–9). We should thus assume that the FH regulates treatment, but to fully understand treatment we frequently will have to pay attention to the attitudes expressed by this treatment.Footnote ²⁶ That it matters how we regard or consider persons is particularly significant in the context of migration where mistreatment is often grounded in stereotypes and prejudices pertaining to race, culture, or religion.

Whilst the way people regard others is important for understanding mistreatment, there is no straightforward correlation between how we regard someone and how we treat them. I might think of someone as an entity without dignity and merely useful to me but I never act on this assessment, for instance, because the opportunity costs of instrumentalizing this person would be too great. This would fall outside of the scope of the FH as we understand it, since it is not a case of treating anyone. Yet, when we treat someone, it often matters how we regard them. Moreover, in many cases, actions clearly betray or express attitudes. It is difficult to see how rioters who set fire to hotels housing asylum seekersFootnote ²⁷ could think of these asylum seekers as people endowed with dignity and as of the same moral standing as everyone else.

It is also possible that I mistreat someone who I think of as unconditionally valuable. I might make a false promise to extract money from a person I consider my moral equal and endowed with dignity and might do so simply because I need the money. This would still be a violation of the prohibition against treating it as a mere means. Yet, when it comes to the ethics of migration, it is significant that, due to biased media reporting and political and public discourse, mistreated migrants will, as a matter of fact, often be regarded as of a lesser status.

5. Mere things

Kant does acknowledge the underlying phenomenon that the category of mere thing captures. He criticizes ‘deadly insensitivity’ (G, 4: 398.25) to others’ needs and emergencies as an extreme form of complacency and maintains that we may not look ‘with complete indifference on the need of others’ (CPR, 5: 69.28). The indifference Kant is talking about here is an extreme form of failing to render aid, for instance when vital interests are at stake and help could be rendered easily and at no great cost. Inaction due to indifference in this sense may be more severe than mere failure to promote imperfect duties and may call into question whether an agent has made the end of others’ happiness their own at all (MM, 6: 390.21–2). This would not simply be a lack of being beneficent or failure to treat others as an end as much as one can. Moreover, Kant criticizes that European colonizers take indigenous people ‘for nothing’ and assume that their lands belonged ‘to no one’ (TPP, 8: 358.34–5). It is interesting that Kant is here not focusing on forms of exploitation that indigenous people were subjected to, such as forced labour in the encomienda system, but on the assumption that they do not really exist, are not persons, and thus their land can be divided among colonizers with no regard for the rights of the people who already live there.

The category of treating as a mere thing captures cases in which agents treat persons as if they were nothing and as if even their most vital ends were irrelevant. However, just as it is legitimate to treat someone as a means, but never merely as a means, we can frequently ignore people and sideline their concerns, treat them as things,Footnote ²⁸ so to speak, as long as we do not reduce them to nothing but things. This means that there are cases in which indifference is ethically defensible, and only some cases of indifference, what Kant calls ‘complete indifference’ (CPR, 5: 69.28) or ‘deadly insensitivity’ (G, 4: 398.25), fall under treatment as a mere thing. We here follow Sticker (Reference Sticker2023: 204), who claims that it ‘is perfectly within our rights, for instance, when confronted with heckling, catcalling or other unwanted attention’ to treat someone with indifference. We may think of these cases as treating someone as a thing but not a mere thing, if we would still call an ambulance if the heckler suddenly became seriously ill or fell victim to an emergency. The mere in ‘mere thing’ indicates that someone who is an end in themselves is reduced to nothing but a (useless) thing, an object of complete indifference.

How to delineate treatment as a thing from mere thing is a difficult and substantive question, mirroring similar difficulties to distinguish between means and mere means. Parfit (Reference Parfit2011: 215) illustrates the latter difficulty via the example of robbers who allow their victim, in this case Parfit’s mother, to choose whether she wants to keep either her engagement ring or her wedding ring: ‘If these people treated my mother as a means, they did not treat her merely as a means. Were they close to doing that? I am inclined to answer No. But this may be a borderline case, in which this question has no definite answer’. We should therefore not be surprised if difficult and marginal questions arise for mere things as well.

Section 2.1 presents at least two intuitively clear examples of treating as a mere thing. Firstly, statutory duties are violated, for instance, by countries that have obligations under international law to accept refugees and to guarantee their safety or by institutions that have legal duties towards, e.g., unaccompanied migrant children in their care. Secondly, there may be an immense disparity between the care and attention various groups receive. Missing British children would elicit concerted search and rescue efforts, but the same does not hold even if many migrant children go missing. At some point this disparity becomes so wide that it is not plausible any longer to say that migrant children are treated as ends in themselves, albeit of lesser significance than British children. Rather, they are treated like mere things, objects of no importance.Footnote ²⁹

We thus propose to use the term ‘mere’ in close analogy to the way it functions in ‘mere means’, but in order to spell out what is wrong with certain cases of indifference rather than with instrumentalization. A mere thing is treated not like a person, since persons are incomparably more than things. A mere thing is also not treated as a useful tool that agents might be invested in for instrumental reasons and thus treat as an object of instrumental use to them. Relative or instrumental worth is deficient when compared to the unconditional worth or dignity of persons. Yet, it is a form of worth that may greatly impact how one is treated. A good means or tool warrants instrumental concern and care to preserve it. Of course, persons warrant care and concern for their own sake. Yet, a person is in a particularly precarious position if, on top of being regarded as devoid of unconditional worth, they are not even judged as useful. Instrumental worth still leaves the potential for horrendous exploitation, but it also means that those treated as a mere means often enjoy a more secure status compared to people who can disappear without anyone seeming to notice because no one is invested in them.

Whilst the prohibition against treatment as a mere thing is stringent, we should not think of it as an extremely demanding prohibition that can only be satisfied by taking an active interest in absolutely everyone. Such a duty would be unreasonably demanding. The demandingness worry, as it specifically pertains to the prohibition against treatment as a mere thing is largely a question of the duty’s scope. Mere means and also mere threat presuppose interaction in the sense that they only constrain our treatment of people we interact with or impact with our actions. They are therefore potentially much more contained in scope. The prohibition against treatment as a mere thing may be of a much wider scope and much more demanding if it entailed an obligation not to treat others with indifference even if we do not interact with them at all.

We think that this is mainly a problem for approaches that avail themselves of the category of mere thing specifically to conceptualize duties of aid and the mistreatment of the globally poor, as Sticker (Reference Sticker2023) has done recently.Footnote ³⁰ Sticker stresses that treating someone as a mere thing is not merely a failure of beneficence. It is an extreme form of denying aid (e.g. in easy rescue cases) for which agents are blameworthy. This does indeed raise the question of whether the scope of the duty could be very wide, extending to people I have never affected with my treatment in any way, and the duty thus very demanding.Footnote ³¹

We think that the category of mere thing is more contained in scope when applied to the mistreatment of migrants. In the case of global poverty, there always remains the question of whether others are better placed to help and whose duty it is to provide life-saving aid precisely because I may not have any special relationship with (not be treating in any way) a person I could aid. In the case of mistreatment of migrants, indifference often appears as blameworthy because refugees die at our borders (not just anywhere) and as the result of policies put in place by representatives we elect, and despite countries having a duty under international law to grant asylum and protect refugees. Refugee children whom the UK government had a duty of care towards disappear from UK hotels without the police searching for them. These are cases of indifference of quite a specific kind resulting in violations of international law or statutory duties and showing an extreme disparity in how certain lives are valued within a country. Treating people with indifference like this is morally criticizable in ways that many other failures to further the ends of others are not.

We can only give a few general indications of how the prohibition against treating as a mere thing would play out in the case of migration. The prohibition captures the distinct badness of ‘complete indifference’ or ‘deadly insensitivity’ to others’ needs and emergencies. In the case of migration, the prohibition primarily requires that states and agents deputized by them live up to statutory duties. As a result, certain forms of inaction on their part would be rights violations or would put people they have responsibilities for at grave risk of harm. Such inaction, when there was a reasonable expectation, maybe even a clear duty, to act would reveal ‘complete indifference’ or ‘deadly insensitivity’. On top of this, extreme disparities between how natives and migrants are treated, within a country or at the border of a country, can be a form of treating as a mere thing. The hotel case, we believe, reveals such an extreme disparity in how certain lives are valued. We take it that it is clear here that the migrant children who disappeared from hotels suffered mistreatment. However, it is a matter of debate who exactly engaged in the mistreatment: specific police officers who did not take the disappearances seriously, civil servants in the Home Office, owners or operators of the hotels from which they disappeared, media outlets, the public more generally, or a combination thereof?

Our point is to establish that the category of mere thing is needed and useful to understand the precarious position of migrants. It is a difficult question what specific obligations the prohibition against treatment as a mere thing puts on various role-holders and private citizens. At the very least, private citizens may have to take action (e.g. writing letters to elected representatives, protesting, campaigning, or volunteering) when there are systemic or large-scale failings in the way role-holders discharge their duties, resulting in extreme disparities in the way citizens and non-citizens are treated.Footnote ³²

6. Mere threats

Kant himself acknowledges the existence and ethical significance of hostility as a prime or ‘first evil’ (MPT, 8: 270.18–9) in the form of ‘vices of hatred of human beings’ (MM, 6: 458.2). These include envy, Schadenfreude, and malice. These vices are directed at wishing for other’s misfortune and distress. When they go ‘so far as to help bring about ills or evil it makes hatred of human beings visible and appears in all its hideousness as malice proper’ (6: 460.1–3). Hostility is rooted in seeing others as competition that threatens our position: ‘upon jealousy and rivalry, can be grafted the greatest vices of secret or open hostility to all whom we consider alien to us’ (R, 6: 27.12–15). Hostility against others ‘originates in the inclination to gain worth in the opinion of others, originally, of course, merely equal worth: not allowing anyone superiority over oneself, bound up with the constant anxiety that others might be striving for ascendancy; but from this arises gradually an unjust desire to acquire superiority for oneself over others’ (6: 27.7–12). Whilst there may be something instrumental about putting others down and inflicting harm on them in order to protect or elevate my own status, others do not appear to be useful for me here. Rather, I feel the need to harm them or undermine their standing because they constitute threats to my own standing to such an extent that I am inflicted with ‘constant anxiety’ about their supposed scheming against me. Means or tools do not usually fill me with terror and I do not have to guard against them.

In public and political discourse, migrants are frequently presented as drains on the public purse or even as active dangers. This is reflected in or mirrored by a hostile social and political environment and by hostility from individuals. In these cases, migrants may be treated as a mere threat. Mere threats are distinguished from anything that is not even a threat but rather useful or an object of indifference (i), as well as from anything that is a threat but not a mere one (ii).

(i) Means, including mere ones, have a positive status insofar as they are useful. Those treated as a (mere) thing or (mere) threat do not have such an instrumentally useful status. Treating a person as a mere threat puts the person in a particularly precarious state, since it is not in someone’s self-interest to ignore a threat. Rather, threats are to be contained or even neutralized and agents may even allocate considerable time, energy and other resources to neutralizing a threat.

There is a further difference between mere means and mere threats that is worth highlighting. If I treat a person as a mere means, this person usually is a means for me, in the sense that they are useful for me. At least in the case of mistreatment of migrants, cases of treating as a mere threat, however, often misfire not just morally but also in the sense that supposed mere threats are not even threats. Treating someone as a mere threat is often based on false assumptions: That migrants (from certain countries) are more likely to commit violent crimes, that they only migrate to exploit the welfare system, and that their culture is incompatible with their host country’s values.Footnote ³³ Thus, it seems that treating someone as a mere threat often also entails an epistemic mistake: Someone who is treated as a mere threat is not even a threat.Footnote ³⁴ Whilst this is significant, because it demonstrates the impact that racist rhetoric and public vilification can have, we do think that this epistemic mistake is secondary. The main problem from a moral perspective is usually how persons are treated.Footnote ³⁵

One significant aspect of epistemic mistakes is that inducing these mistakes in others, getting one group to consider another group as a mere threat, can be instrumentally useful (see our Section 2.2). For instance, a politician may vilify migrants to distract from his own mistakes or to rile up his base. This politician, if he, so-to-speak, did not drink his own Kool-Aid, treats the group he vilifies as a mere means. The people who buy into the rhetoric, however, if they call for the group to be deported, kept out of the country, or maybe even attack members of the group, are best understood as treating the group as a mere threat. For the politician the vilified group has instrumental value as a distraction or a tool by which to garner support, specifically because he can present the group as being of instrumental disvalue, a threat, to others.

(ii) There are, as a matter of fact, people who do pose threats to others. It is legitimate to avoid these people or defend oneself against them.Footnote ³⁶ Treating someone as a threat (but not a mere threat) is morally permissible. This is no different from mere means. People can be means for others in the pursuit of their ends, and it is legitimate to treat them as such, as long as people are not treated as if they were nothing but means. Likewise, the ‘mere’ in mere threat indicates that someone is reduced to the status of a threat and stripped of their status as a person.

Our term ‘threat’ is admittedly broad and technical. Treating someone as a mere threat can include overtly hostile treatment or acts of hatred and contempt as well as more subtle and everyday phenomena. In fact, we think that the category of mere threat consists of a wide spectrum. What underlies all forms of treating someone as a mere threat is that victims are treated as of instrumental or inherent disvalue and of no intrinsic value as persons.

On the one end of the spectrum there is treating someone as a burden, e.g., on the public purse or as an obstacle that happens to hinder pursuit of my ends, in which case their disvalue is contingent. There is nothing intrinsically wrong with such a person. On the other end of the spectrum there is treatment as an outright mere enemy, someone of inherent disvalue. This is often the result of racialization and coordinated vilification of a group of people that then appears as dangerous no matter what.Footnote ³⁷ Those treated as a mere enemy are often regarded as less than human, because they do not just happen to pose obstacles but rather are supposedly inherently hostile and dangerous (by their very nature). Mieth and Rosenthal’s (Reference Mieth, Rosenthal, Horn and dos Santos2022) category of treating someone as a negative end spells out the most extreme form of treatment as a mere threat, as here harming and especially degradation of another person is the ultimate purpose. This covers cases of mistreatment for which it is essential that the victim is a person and the perpetrator seeks to deny or undermine this status.

We should stress that we do not intend the category of mere threat on its own to settle specific questions in the debate about migration, such as whether borders must be open. We do not think that all policies that restrict migration, that make movement across borders more difficult or that distinguish between citizens and non-citizens would count as treating migrants as a mere threat.Footnote ³⁸ However, the duty against treating as a mere threat leads to straightforward prohibitions against many of the most blatant mistreatments migrants suffer: hate crimes that aim to scare them out of the country or disenfranchise them from public life as well as vilification that seeks to perpetuate the perception of them as dangerous and that encourages others to treat them as a mere threat. For example, consider how Britain’s ‘hostile environment’ policy is not only implemented ‘through administrative and legislative measures’ but also by citizens. ‘The measures were designed to make the lives of people without legal immigration status difficult, so that they are forced to leave the country. The policy also empowers figures across British society to become quasi-immigration officers, such as employers, landlords, and National Health Service administrators’ (Bhatia Reference Bhatia2020: fn. 2). Citizens may have a duty to resist being deputized to treat migrants as a mere threat.Footnote ³⁹

Before we move on to consider two objections, let us first respond to a concern that can be dealt with quickly. We do not mean to suggest that different forms of mistreatment are discrete such that they can never occur together. It is perfectly conceivable that a person is mistreated by one agent in one form and, in another, by another agent and that these forms of mistreatment interact with and reinforce each other. Moreover, an agent may treat a person as a mere thing at one time but as a mere means or mere threat at another. Take for instance one of the Kantian examples we already presented, the treatment of indigenous people (Section 5). Kant worries that European colonizers take them ‘for nothing’ and consider them ‘no one’ (TPP, 8: 358.34–5) or treat them as a mere thing. However, we can assume that if indigenous people were to object to this treatment and even fight back against land grabs, their treatment would quickly transition from that of a mere thing to that of a mere threat.Footnote ⁴⁰ Moreover, a number of philosophers have pointed out that the worst forms of wrongdoings towards certain groups are often only possible through the indifference of others, such as bystanders and the public at large (Geras Reference Geras1998), and that indifference can facilitate other forms of severe wrongdoing (Norman Reference Norman2020: ch.1).

7. Two objections

Finally, let us look at two objections, namely, that new categories of mistreatment are unnecessary and that our framework cannot account for duties to self. Addressing these objections will allow us to refine our proposal.

Firstly, as we already pointed out (Section 3), Kant maintains that those not treated as persons are treated as of ‘only a relative worth, as means’ (G, 4: 428.21). This suggests that the underlying problem with treating a person as a mere means is that we make this person’s value solely dependent on our own ends and on how the person relates to these. ‘Mere means’ should then not be understood in a narrow sense as instrumentalizing someone but as treating persons as if they only had relative or conditional worth. We therefore do not need additional categories of mistreatment, as they are already implicitly part of the original FH, and our version of the FH appears unnecessarily cumbersome.

In reply, we should point out that this objection assumes a very technical and broad understanding of ‘mere means’, which a majority of Kant scholars reject (see our Section 3). However, we admit that this reading has explanatory power. It contains a unified account of why treating persons as a mere means, mere things, and mere threat is deficient: I make my treatment of them solely dependent on my own ends. Thus, we could accept this and even propose a reformulation of the FH which would be normatively equivalent to our supplementation of the FH: Treat others as ends in themselves and not as of only relative worth. However, we think that Kant presents the second part of the FH in terms of mere means, instead of in more general terms of relative worth, for a reason. Mere means is a more concrete notion than the highly formal and abstract requirement to not treat others as of only relative worth.Footnote ⁴¹ It is intuitively clear in many cases whether a course of action would be a form of treating someone as a mere means, in the sense of a tool. After all, agents are familiar with the way they treat tools and how this contrasts with how they usually treat persons. This more concrete way of putting the formula better serves its function to be action-guiding. Kant explicitly maintains that the FH can bring the moral law closer to ‘intuition’ and ‘feeling’ and can thus help to ‘obtain access for the moral law’ (G, 4: 436.8–437.4). Its action-guiding function is clearly important to Kant.

Our main point is that we need equally action-guiding and applicable categories for cases where persons are not mistreated due to their instrumental value. The two additional categories of mistreatment we developed in this article allow us to maintain the general structure of the FH as it stands, an all-encompassing command and specific strict prohibitions, and at the same time accommodate the different types of mistreatment: treating as a mere means, mere thing, mere threat. Our supplemented FH is closer to the original formula and more easily action-guiding than a more radical reformulation would be.

Secondly, the FH does not only refer to duties to others but also to duties to oneself. So far, we have not mentioned duties to self. If there were no corresponding duties to self for treating as a mere thing and mere threat, then this would indicate that these categories could not be parts of the FH equal to the prohibition against treatment as a mere means, which grounds duties to others and to self.

Duties to self are beyond the scope of our article, and as a result, our proposals must be tentative. We should first point out that the category of duties to self is often met with suspicion,Footnote ⁴² especially when it comes to the perfect duty not to use oneself as a mere means by committing suicide. There are, however, notable recent Kantian defenders of duties to self. Strikingly, some such defences suggest the existence of violations of duties to self that may correspond to mere enemy and mere threat. For instance, Luke Davies (Reference Davies2024: 5) holds that ‘we violate a duty to self when we act in a way that destroys, degrades, or impairs the source of our dignity (i.e. our capacity for morality) and when we act in a way that is inconsistent with our equal moral status’. Since Davies speaks of a ‘violation’ of a duty to self, he likely has in mind perfect duties, not imperfect duties, which work on a framework of degrees rather than a binary one of fulfilment or violation (MM, 6: 390.19–21). Perfect duties correspond to strict prohibitions. Yet, none of the violations Davies mentions seem to be specifically matters of treating oneself as a mere means. Rather, Davies worries about self-destruction and accepting a lower status. Destruction, degradation, or impairment is how a mere threat is treated. In fact, Sticker (Reference Sticker2025: 1327) suggests, without elaborating on this further, that agents ‘may treat themselves as mere enemies when they internalize negative stereotypes about groups they are a member of and subsequently their deliberations and actions become informed and shaped by these negative stereotypes’, and when members of marginalized groups ‘take over the perspective of their oppressors’. Internalization of certain negative stereotypes is one way in which we can envisage destruction, degradation, or impairment of one’s source of dignity, an attitude towards oneself that may constitute treatment of oneself as a mere threat.

Moreover, the second way to violate a duty to self, according to Davies, is to ‘act in a way that is inconsistent with our equal moral status’.Footnote ⁴³ This, on its own, is not sufficient to constitute a treatment of oneself as a mere thing, e.g. when I act in a way that assigns me a slightly lesser moral status. This may be a failure to treat myself fully as an end, but not yet treatment as a mere thing, an object of no use and no moral standing. An extreme case of someone who fails to treat oneself as an end is presented by Kant himself as ‘one who makes himself a worm’ and who ‘cannot complain if people step on him’ (MM, 6: 437.24–6). This extreme case is not one of instrumentalization. Kant does not intend worms as examples of tools. Rather, a worm is an entity considered so low and so unworthy of attention that anyone may step on it. Kant is here clearly speaking metaphorically. Less metaphorical examples for extreme cases of treating oneself as mattering less than others are, according to Kant, being ‘a parasite or a flatterer or … a beggar’ (6: 436.21–2). Notably, these examples are listed in Kant’s discussion of perfect duties to oneself. Kant is acknowledging the phenomenon that someone may consider themselves much or infinitely lower than others and act accordingly. He thinks of this as a violation of a perfect duty to self, and we think that such a violation is best understood as a violation of the prohibition against treating oneself as a mere thing.Footnote ⁴⁴

It is another question whether such violations of duties to oneself are blameworthy or criticizable, given that people who take over the perspective of their oppressors or who act as if they do not matter may not be in a position to stand up for themselves and should be considered victims of injustice, not perpetrators. There is in fact now an illuminating debate about whether the very concept of duties to self should be considered victim-blaming or rather can function as a source of empowerment (Hay Reference Hay2011; Mosayebi Reference Mosayebi2023). For the purposes of this article, we must bracket this question. We hope to have at least indicated how the category of mere threat and mere thing can be applied to treatment of oneself and how doing so captures important ethical phenomena as well as making sense of some of Kant’s own remarks about perfect duties to self.