This article offers a thorough analysis of the systematic significance of gratitude in Kant’s practical philosophy. As M. Timmons (2011) has convincingly argued, the duty of gratitude holds profound moral relevance insofar as it involves a relationship where both the beneficiary and the benefactor are treated as ends in themselves, thus promoting the moral progress of humankind by adhering to the Humanity Formula of the categorical imperative. Furthermore, by exploring the origins of ingratitude, scholars such as Moran (2016) have shown that the absence of gratitude erects an epistemic barrier, hindering the recognition of mutual interdependence (Herman, 1984) and, by extension, our intrinsic vulnerability (Formosa, 2013). This recognition of vulnerability and interdependence is crucial to understanding the essentially relational nature of personal autonomy. By highlighting these aspects of the human condition, the Kantian reflection on gratitude enables us to engage with broader issues such as global distributive justice (Loriaux, 2020; Rushdy, 2020), the collective ownership of natural resources (Vereb, 2022), and intergenerational justice (Gómez-Franco, 2020). Thus, gratitude emerges as a pivotal concept for a comprehensive understanding of Kant’s practical philosophy.1

Kant establishes a distinction between ‘duties of right’ (Rechtpflichten) and ‘duties of virtue’ (Tugendpflichten) based on the nature of the ‘obligation’ (Verbindlichkeit) they impose. Duties of right are considered ‘narrow’ (eng) as they define the obligation to perform a specific action, whereas duties of virtue demand the pursuit of a particular end while allowing a certain ‘playroom’ (Spielraum, latitudo) (cf. MS, AA 06: 390.06-07) that offers various means of fulfillment. These duties are thus ‘wide’ (weit) and, while their fulfillment cannot be legally enforced, they are regarded as ‘meritorious’ (verdienstlich) (cf. MS, AA 06: 227.30-31).2

Kant considers ‘gratitude’ (Dankbarkeit) as a duty of virtue and places it within the ‘duty of love to other human beings’ (Liebespflicht gegen andere Menschen). The main duty of love is ‘beneficence’ (Wohltun), and the expected response is gratitude.3 There is a duty to feel gratitude in response to the ‘benevolence’ (Wohlwollen) of a benefactor, that is, whether that intention is ultimately realized in the desired and anticipated benefit—regardless of its “physical results” (physische Folgen; MS §31, AA 06: 455.02). There is no duty to perform specific acts of beneficence, especially if they require sacrificing one’s own well-being (cf. MS §31, AA 06: 454.02-04). However, it is morally necessary to adopt the maxim of beneficence, in contrast to strict duties such as the prohibition of killing or lying, which require complete adherence in every specific act:

One of the issues that comes across in this context is the connection between the notion of duty (in this case of gratitude) and of sentiment. We have the right not to be robbed, killed, or lied to; we may even have the right to expect that gratitude is shown to us, even if it is not genuinely felt (cf. Berger 1975), but we might ask whether we can demand that others be grateful, given that we expect a specific emotional response (cf. Card 1988, p. 117; Fitzgerald 1998, p. 120). This would imply that the agent controls their emotions, which cannot be demanded from any individual—considering also that the granting of the benefit occurred without any obligation on the part of the benefactor.4 To put it in other terms: the duty of gratitude is moral, not legal. There would be no merit in expressing gratitude if it were mandated by law and ingratitude were penalized (cf. Seneca 1935, Book III, §§6-10).5 In Rousseau’s terms: “The expression of gratitude (reconnaissance) is indeed a duty that must be fulfilled, but not a right that can be demanded” (Rousseau 1992, p. 244). In this sense, gratitude constitutes an imperfect duty. We could understand this affective requirement in terms of the maxim of being predisposed to return the favor to our benefactor on a future occasion (cf. Guyer 1993, p. 386) or, in a more general way, as a duty to cultivate certain feelings which would ultimately lead us to a benevolent disposition toward others, i.e. philanthropy or ‘love of human beings’ (Menschenliebe) (cf. MS §33, AA 06: 456.08-16):

However, for it to be legitimate to expect a grateful response, the act of beneficence must meet the following criteria:

The Kantian conception of benevolence implies that the benefactor adopts our ends as their own, going beyond a mere “benevolence in wishes, which is, strictly speaking, only taking delight in the well-being of every other and does not require me to contribute to it (everyone for himself, God for us all)”, to advance toward “active, practical benevolence (beneficence), making the well-being and happiness of others my end” (MS §28, AA 06: 452.01-05).7 That is to say: the concepts of benevolence and beneficence must be distinguished: “Benevolence is satisfaction in the happiness (well-being) of others; but beneficence is the maxim of making others’ happiness one’s end, and the duty to it consists in the subject’s being constrained by his reason to adopt this maxim as a universal law” (MS §29, AA 06: 452.26-30).8

The maxim of beneficence has a broad application because, as we stated before, promoting the happiness of others by sacrificing one’s own would be a contradictory maxim (cf. MS, AA 06: 393.29-32). Moreover, practical benevolence refers to physical well-being as an integral part of another person’s happiness, to which moral well-being must be added. In relation to this moral well-being, my obligation is negative and consists in not creating a situation that could cause the other to experience remorse—a feeling that, while having a moral origin, often leads to physical effects such as fear, embarrassment, etc. In other words, the act of benefiting the other must be performed in such a way that they do not feel humiliated in their sovereignty and self-esteem, respecting at all times “the dignity of humanity in another person,” that is, what Kant refers to as “respect in the practical sense (observantia aliis praestanda)” (MS §25, AA 06: 449.29-30):

As we will see in the next section, the humiliation arising from the feeling of inferiority one may experience when being benefited by another is one of the main causes of ingratitude.

Once the objective criteria of a benevolent action are met, what response is expected from the beneficiary?, that is, what does the duty of gratitude entail?10 Kant identifies two aspects to consider in evaluating the adequacy of the response: intensity and extent (cf. MS §33, AA 06: 455.26-456.16).

The first condition for a relationship of gratitude to exist is that the beneficiary must accept the benefit.11 The intensity with which one should respond to a benevolent act depends on the level of selflessness with which it was done, the cost to the benefactor (self-sacrifice and effort), the type of relationship with them, and the magnitude of the benefit. An example of a highly meritorious act of beneficence would be one in which “at considerable self-sacrifice I rescue a complete stranger from great distress” (MS, AA 06: 228.16­17). In other words, a duty of gratitude is incurred for acts that go beyond what is morally required, thereby acknowledging an abundance or excess beyond what duty strictly demands. In turn, gratitude is also owed in cases of exceptional actions or qualities. Conversely, it is considered a sign of ingratitude—and a failure to understand the benevolent nature of the act—to obsess over repaying the favor with the same level of intensity or volume as the gift received, since the benefit is granted without the intention of receiving anything in return.12

For Kant, gratitude constitutes a “sacred duty” (heilige Pflicht) (MS §32, AA 06: 455.12), meaning that “the obligation with regard to it cannot be discharged completely by any act in keeping with it (so that one who is under obligation always remains under obligation)” (MS §32, AA 06: 455.16-17). Kant identifies the origin of ingratitude in the beneficiary’s situation of inferiority—and the pride and powerlessness it causes (MS §35, AA 06: 458.15-19). However, the debt of gratitude can never be fully repaid due to the temporal priority of the benefactor, who initiates the chain of favors; it is this priority that transforms the gift into a permanent debt:

And, in fact, it is not merely a temporal precedence in the benevolent action: the absolute nature of freedom, the fact that a particular moral agent decides to act for the sake of another, also explains the impossibility of full repayment, the indelible nature of the debt, and the “inequality of status” between benefactor and recipient that results from it (Loriaux 2020, p. 16).

Given this impossibility, one might question the extent to which we can speak of a duty of gratitude if what is required of us can never be fully accomplished. A possible resolution lies in distinguishing between the type of relationship established between a benefactor and their beneficiary, and that between a creditor and their debtor.14 In the latter case, once the debt is repaid, any kind of relationship is canceled. However, as we will further develop in the following section, in acts of beneficence the duty of gratitude does not end the interaction but rather enhances the moral appreciation and esteem for the one who has adopted the ends of our action as their own. We are grateful “not merely for the good we have received, but also for the fact that the other is well disposed (gute Gesinnung) toward us” (V-Mo/Collins, AA 27: 441.32-34). In other words, the debt is irredeemable because it is never fully canceled, as it involves the establishment of the beneficiary’s moral bond with the benefactor, a community tie. In the experience of gratitude, there is no mere exchange or commercial transaction that can be settled by returning the good or service; it is a relationship that transforms the moral identity of the participants, allowing both to recognize each other as members of the same moral community. For this reason, where the possibility of reciprocity ceases (for example, due to an act of ingratitude), the other is no longer considered capable of proposing morally valuable ends. In other words, we stop expecting anything from the other and shift from the second person (addressing the other directly) to the third person (talking about the other) (cf. Korsgaard 1996, p. 205).

This point connects with the issue of the extent of the duty of gratitude: if the benefactor is still alive, our gratitude should be directed to them; otherwise, we have the responsibility to extend it to others. Even if the benefactor is no longer in a position to receive gratitude—perhaps because they have passed away—the benefits derived from their actions should be extended to others (cf. MS §33, AA 06: 456.06-08). Every act of gratitude is an invitation to cultivate our benevolence toward others (our love for humanity), and for this reason, those who fail in their duty of gratitude risk losing others’ trust and becoming isolated from the community. Gratitude acts as a social lubricant in that ingratitude can lead to enmity and resentment, potentially resulting in conflict.15

The permanent nature of the debt inherent in the benefactor-beneficiary relationship partly explains why receiving a benefit can compromise our autonomy, making us dependent on our benefactor. For this reason, Kant asserts that it is advisable not to accept benefits that one can do without (cf. MS §12, AA 06: 436.19­21). As stated earlier, the weight of the debt—feeling dependent or inferior—is one of the main causes of ingratitude:

However, a world in which we are not entitled to expect gratitude for our benevolent acts is a world in which the sense of community is lost. For Kant, ingratitude—along with envy and Schadenfreude (cf. V-Mo/Collins, AA 27: 440.26-28; MS §36, AA 06: 458.21-24)—is one of the three vices that constitute the essence of evil and cruelty and represents a form of inhumanity and ‘misanthropy’ (Menschenhasses) (cf. V-Mo/Collins, AA 27: 439.36-440.04). This pernicious effect of ingratitude, which Kant describes as a “scandalous example” (skandalöses Beispiel) for the community (MS §32, AA 06: 455.14), not only affects the person who suffers from it in their willingness to continue benefiting the ungrateful, but even witnessing an act of ingratitude has a deterrent effect on future acts of beneficence (cf. MS §36, AA 06: 459.28-31).16 For this reason, gratitude constitutes for Kant “a sacred duty, that is, a duty the violation of which (as a scandalous example) can destroy the moral incentive to beneficence in its very principle” (MS §32, AA 06: 455.12-15). In other words, an act of ingratitude attacks the due respect for human beings as moral agents and carries the danger of dismantling the community by provoking imitations (cf. MS §40, AA 06: 464.12-13).

In summary: ingratitude violates social customs (in terms of courtesy and etiquette), deteriorates social bonds and, as we will see below, is contrary to moral law.

The requirement that the maxim (subjective principle) of an action can be a valid principle for every finite rational being (objective practical principle) is the criterion by which we can determine its morality, i.e., the moral law as the fundamental law of practical consciousness (cf. KpV, AA 05: 19.07-12). The ‘principle of morality’ (Prinzip der Sittlichkeit) lies in the necessary conformity of the principle that governs an action with the form of universality that is constitutive of every law: “There is, therefore, only a single categorical imperative and it is this: act only in accordance with that maxim through which you can at the same time will that it become a universal law” (GMS, AA 04: 421.06-08).

Universality and necessity are the traits by which we can discern the morality of the principle behind the maxim of our action. However, since these properties are shared by both the moral law and any natural law, it raises the question of what distinguishes the two. In this context, it is crucial to emphasize the eminently spontaneous nature of the will, as it produces certain effects in the sensible world (cf. KpV, AA 05: 89.20-33). Regarding what motivates us to act—the ‘end’ (Zweck) of the action—it can be said that the value of any object of our inclination is relative, as it ultimately depends on the acceptance of that inclination as a determining ground. Nevertheless, what is no longer relative is the capacity itself to accept or reject a particular inclination as the motive for our action, that is, reason as the faculty of ends; thus, it is by virtue of reason that every finite rational being is established as an ‘end in itself’ (Zweck an sich selbst) (cf. GMS, AA 04: 438.08-16). Respect for ‘humanity’ (Menschheit) both in ourselves and in others as the unconditional source of normativity enables us to reformulate the categorical imperative in the following terms: “So act that you use humanity, whether in your own person or in the person of any other, always at the same time as an end, never merely as a means” (GMS, AA 04: 429.10-12). This respect for humanity is based on the ‘dignity’ (Würde) that we recognize in beings who obey no law other than the one they themselves impose on themselves (cf. GMS, AA 04: 434.25­30). Consequently, the maxim of our action is not universalizable if it undermines the capacity of every finite rational being to self-impose ends, that is, if it treats them merely as a means to our desires (cf. GMS, AA 04: 429.20-23).17

And, to the extent that the morality of the maxim requires it to be universally valid, the categorical imperative can be formulated as fostering a community of rational beings who act according to a law that regards them collectively as ends in themselves, i.e., through the concept of a ‘Kingdom of Ends’ (Reich der Zwecke): “Consequently, every rational being must act as if he were by his maxims at all times a law-giving member of the universal kingdom of ends” (GMS, AA 04: 438.18-21), where ‘kingdom’ (Reich) should be understood as a “systematic union of various rational beings through common laws” (GMS, AA 04: 433.17-18).18 Thus, the fulfilment of the demands of the moral law is synonymous with the realization of the Kingdom of Ends.

18

Now, to say that an act of beneficence is disinterested means that it is performed out of respect for the other person as an end-in-itself, respecting their character and nature as an end. This is what Kant describes as the duty of love toward others: to take their ends as our own. Kant refers to this as ‘practical love’ (praktische Liebe) to distinguish it from pathological love or mere delight in others, as no duty can be derived from an empirical (psychological or anthropological) element:

Furthermore, the duty of gratitude requires the beneficiary to respect the benefactor for the benefit she has provided, rather than reducing them to a mere instrument serving our interests. In this way, in the benefactor- beneficiary relationship, both parties are considered ends in themselves. This advances the realization of the moral demands of the categorical imperative, since setting aside one’s own interest allows for the universalization of the maxim of our action. To put it in another words: the maxim of ingratitude is immoral as it violates the Humanity Formula of the categorical imperative: the ungrateful person treats others merely as a means to satisfy their own private interests and thus fails to regard them as ends in themselves (cf. Timmons 2011, p. 266). Kant also asserts that the duty of gratitude extends “to one’s predecessors, even to those one cannot identify with certainty (die man nicht mit Gewißheit namhaft machen kann)”; MS §33, AA 06: 455.27­28), and that if the benefit cannot be returned due to the benefactor’s death, the chain of favors should be extended to other members of the community.19 Thus, gratitude becomes a duty that can be extended to all of humanity, acting as a facilitating factor in the realization of the Kingdom of Ends and thus to the moral progress of all mankind.20

As discussed earlier, Kant uses an analogy with nature to define the Kingdom of Ends: “A kingdom of ends is thus possible only by analogy with a kingdom of nature” (GMS, AA 04: 438.23-24).21 In the analogy drawn between the sensible and intelligible realms, Kant considers not only the ‘conformity to law’ (Gesetzmäßigkeit) that characterizes the concept of nature in a formal sense but also the rational assumption of its teleological character—thinking of this diversity of elements as systematically ordered toward certain ends. To think of the maxim of our action in terms of the concept of a Kingdom of Ends means to conceive it as part of a whole governed by the demands of the categorical imperative. Thanks to the analogy with the physical world, this moral world composed of rational finite beings is envisioned as subject to the same physical laws of ‘attraction and repulsion’ (Anziehung und Abstoßung) that govern the interactions of sensible beings. The moral translation of these physical laws is also present in the relationship between benefactor and beneficiary: the ‘principle of reciprocal love’ (Prinzip der Wechselliebe)—in the sense of the practical love previously developed—promotes a rapprochement between moral agents, while the ‘principle of respect’ (Prinzip der Achtung) requires a certain ‘distance’ (Abstand) (cf. MS §24, AA 06: 449.04-15), i.e. the strict requirement of not diminishing the other in their humanity. In summary: the principle (of love) by which we adopt the ends of the other as our own must be limited by the principle (of respect) that indicates we must allow the other to establish the ends they wish to pursue. Kant finds the most intimate union of love and respect in the relationship of friendship (cf. MS §46, AA 06: 469.17-18).22

Benevolence and gratitude, both embedded in Kant’s duty of love to other human beings, would allow us to recover the beauty of the world, to humanize the “nation of devils” (Volk von Teufeln) (ZeF, AA 08: 366.16):

If we consider the relationship between benefactor and beneficiary as essential to realizing the Kingdom of Ends, then ingratitude must be seen as inherently immoral. This is because, as previously mentioned, ingratitude violates the Humanity Formula by reducing the other person to a mere instrument for achieving our own goals. This violation constitutes a form of vulnerability, in that each party risks being treated as mere means to the ends of others. However, there is a deeper sense of vulnerability, which is tied to our fragile condition that makes us interdependent beings.23 Understanding the essence of gratitude enables us to acknowledge this inherent vulnerability and the interdependent nature of human life (Herman 2012, p. 402).

Ingratitude involves establishing epistemic barriers in our relationship with others. These take the shape of a false sense of sovereignty and independence. The ungrateful person incorrectly believes themselves to be fully self-sufficient, which leads to her inability to recognize the dependence on others (cf. Moran 2016, p. 352f.). Ingratitude is thus strongly linked to a lack of humility (cf. Roberts 2016, p. 65f.).24 This situation of codependence is acknowledged by Kant when he asserts that the relationship of beneficence requires treating others as ends in themselves (and thus being regarded as such ourselves) and that this relationship arises from our need to be loved, i.e., “helped in case of need” (in Nothfällen geholfen; MS, AA 06: 393.18). Ingratitude, therefore, stems from both a misunderstanding of the concept of self-sufficiency, as it is perceived as a threat to our autonomy, and a misguided comparison with others that, rather than stimulating our moral perfection, debases us, leading to envy and “Schadenfreude” (joy in others’ misfortune):

The maxim of ingratitude is not universalizable as it involves a contradiction: one simultaneously acknowledges having benefited from someone else’s action while claiming not to need any help. This internal inconsistency undermines the principle of universality central to Kantian ethics. Ingratitude fails to respect the moral worth of others as ends in themselves and disrupts the mutual recognition and dependence required for a harmonious moral community:

The relationship of beneficence operates on the presumption of our mutual finitude and “defines a community of mutual aid for dependent beings” (Herman 1984, p. 591). Recognizing this reciprocity implies accepting that we are not self-sufficient and, therefore, acknowledging our vulnerable and dependent nature —or, as B. Herman designates it, ‘the ubiquity (inescapability) of the possibility of needing help’ (Herman 1984, p. 584). As my benefactor shares this same vulnerable condition, I can, in turn, become a benefactor myself —and potentially, to any other member of the Kingdom of Ends. In other words, what has been framed from the perspective of finitude (the mutual recognition of our dependent nature) can be approached from our condition as rational beings: we are capable of providing the help that others might need. In this way, within the benefactor-beneficiary relationship, I simultaneously recognize myself as both dependent and autonomous. That is: through gratitude we also affirm “our status as independent agents” (Herman 2012, p. 402).

The duty of gratitude enables us to acknowledge our interdependence, compelling us to step outside of ourselves and consider others in our decision-making. And, given that we all share the same “dwelling place” it is appropriate to address the issue of intergenerational or prospective justice (which concerns the obligations, if any, we have toward future generations)26 as well as the common ownership of the Earth (Vereb, 2022), an idea expressed by Kant in the following terms: “the maxim of common interest, of beneficence toward those in need, is a universal duty of human beings, just because they are to be considered fellowmen (Mitmenschen), that is, rational beings with needs, united by nature in one dwelling place (Wohnplatz) so that they can help one another” (MS §30, AA 06: 453.12-15; see also ZeF, AA 08: 358.09-13). In other words, the inherent finitude and vulnerability of the human condition underscores the need to adopt a relationship with nature that transcends purely instrumental concerns, showing gratitude not only for the resources it provides but also for the beauty it allows us to experience:

In addition, if the benefit provided by the benefactor is no longer perceived as a gift but rather as a form of compensation for the unequal distribution of wealth and opportunities—stemming from historical injustice or moral misfortune—Kantian reflection on gratitude also provides conceptual tools to address global distributive justice.27This is especially relevant considering Kant’s view that inequalities of wealth are, “for the most part” (größtentheils), the outcome of political decisions:

In this context, the concept of “misplaced gratitude”— that is, expressing thanks for something to which we already had a right—becomes highly relevant (cf. Rushdy 2020, pp. 279-287), especially since the expression of gratitude cannot be used as an excuse or substitute in situations where institutional resources are lacking (cf. Schott 2016, p. 293).

For Kant, there is a duty of gratitude as a response to the benevolent intention of a benefactor. The benevolence of a moral subject involves a relationship of love toward other finite rational beings, insofar as the said subject adopts the ends of others as their own and refuses to treat them solely as a means to satisfy individual well-being. Gratitude, when understood as the duty of “honoring a person for a benefit they have bestowed upon us” (MS, AA 06: 454.31-32), does not reduce a benefactor to a mere instrument for advancing one’s private interests—whether past, present, or future. Instead, it is rooted in a genuine feeling of respect for the benefactor as such. Expressed in other terms: what is proper and characteristic of the benefactor- beneficiary relationship is that each one considers the other as an end in itself. And, since Kant asserts that the duty of gratitude also extends to ancestors (cf. MS §33, AA 06: 455.26-28), it is an obligation that can be extended to humanity as a whole, which allows us to think of the relationship of beneficence and the imperfect duty of gratitude as contributing elements in the realization of the Kingdom of Ends and hence to the moral progress of humanity.

On the other hand, the Kantian reflection on gratitude enables us to recognize finitude and vulnerability, along with mutual interdependence as inherent elements of human relationships. Likewise it reinforces a conception of human freedom where personal autonomy can only be understood in an intersubjective way— that is, always in relation to others. This dependence is based, among other factors, on the fact that we are embodied selves: “the body is the total condition of life, so that we have no other concept of our existence save that mediated by our body, and since the use of our freedom is possible only through the body, we see that the body constitutes a part of our self” (V-Mo/Collins, AA 27: 369.16-20), and we can dispose of one and just one body in a lifetime.

Finally, the recognition of the vulnerable condition of every finite rational being, and the interdependent relationships that arise from sharing one dwelling place, opens the door to considering our duties toward other members of our species—both present (global distributive justice) and future (intergenerational justice). It also enables us to envision a non-instrumental relationship with nature. For these reasons, the reflection on the imperfect duty of gratitude assumes crucial systematic importance in Kant’s practical philosophy.