Text written in collaboration with Renata Biana da Silva
Ethics is one of the oldest fields of philosophy, involving questions about what is morally right or wrong, how we should live, and what constitutes a good life. Throughout history, different ethical systems have emerged to try to answer these questions, with Aristotle and Immanuel Kant being two major representatives of this philosophical tradition. At first glance, their ethics seem divergent: Aristotle’s ethics, teleological, focuses on the pursuit of eudaimonia (happiness) through the development of virtues; while Kant’s ethics, deontological, is based on the fulfillment of moral duty.
However, this essay proposes that, despite the obvious differences, Kantian ethics can be understood as a reformulation or resumption of fundamental Aristotelian principles. Through a comparative analysis of themes such as the role of reason, the concept of ultimate end, the relationship between virtue and duty, and the connection between happiness and morality, it is possible to conclude that Kant’s ethics, at its core, preserves and develops central aspects of Aristotle’s ethics.
I. Aristotelian Ethics: Virtue and Eudaimonia
Aristotle, in his Nicomachean Ethics, proposes that all human actions aim at some good. He begins with the famous statement that “every craft and every inquiry, as well as every action and choice, seems to tend to some good” (Aristotle, 1998). The supreme good, the one that everyone seeks for its own sake, is eudaimonia, often translated as “happiness” or “human flourishing.” Eudaimonia, for Aristotle, is the ultimate end of human life, and the way to achieve it is through the practice of virtues.
For Aristotle, virtues are dispositions of character that allow us to act in accordance with reason. He describes virtues as a “middle ground” between two extremes: deficiency and excess. For example, courage is the virtue that lies between cowardice (deficiency) and rashness (excess). This idea of virtue as a balance or moderation is central to Aristotelian ethics.
Another important aspect of Aristotelian ethics is the role of reason. Aristotle argues that humans are by nature rational beings, and that the good life for humans is one lived in accordance with reason. He states that “the proper function of man consists in an activity of the soul that is in accordance with reason” (Aristotle, 1998). Therefore, virtue is the excellence of reason, and the virtuous life is one in which reason governs the actions and passions of the individual.
In this way, Aristotle sees morality as an integral part of what it means to be human and to live well. Happiness (eudaimonia) is achieved through the continued practice of virtues, and these virtues, in turn, are determined by reason.
II. Kantian Ethics: Duty and Categorical Imperative
Immanuel Kant, in turn, developed an ethics that is often described as deontological – based on the fulfillment of moral duty. For Kant, the moral value of an action does not reside in its results, but in the intention behind it. He claims that the only thing that is unconditionally good is “good will,” defined as the disposition to act in accordance with moral duty. Kant’s famous phrase in his Groundwork of the Metaphysics of Morals expresses this clearly: “There is nothing, anywhere in the world or outside it, that can be considered as good without limitation, except a good will” (Kant, 2003, p. 16).
The fundamental principle of Kantian ethics is the categorical imperative, which he formulates in several ways. The best-known formulation is: “Act only according to a maxim such that you can at the same time will that it should become a universal law” (Kant, 2003, p. 30). The categorical imperative can be understood as a universal moral law that applies to all rational beings, regardless of their personal inclinations or desires. For Kant, to act morally is to act in accordance with duty, and duty is determined by reason.
Like Aristotle, Kant gives a central role to reason in his ethical theory. For Kant, reason transcends a mere means to achieve happiness, becoming the source of moral obligations. Moral action, for Kant, must be guided by pure reason, which tells us what we ought to do, regardless of the consequences. Kant rejects any form of consequentialist ethics, insisting that moral duty is absolute and unconditional.
III. The Role of Reason: Convergences and Differences
When comparing the two ethical systems, an important point of connection is the role of reason. For both Aristotle and Kant, reason is the central faculty that guides moral action. In Aristotle, practical reason helps us discern the “just mean” in each situation and act in accordance with the virtues. For Kant, practical reason allows us to formulate and follow the categorical imperative, ensuring that our actions are morally correct. Although their conceptions of reason seem different — in Aristotle, it is more oriented toward particularity and context, while in Kant, it is oriented toward universality and formality — both philosophers agree that morality is deeply connected to the human rational capacity. Moral action, for both, is that which is in accordance with reason. While for Aristotle, reason guides us toward eudaimonia—through the practice of virtues—for Kant, reason guides us toward the fulfillment of moral duty through the categorical imperative.
IV. Virtue and Duty: A Dialectical Relationship
Another point of connection is the relationship between virtue and duty. For Aristotle, virtue is a disposition of character that leads us to act in accordance with reason and thus achieve happiness. The practice of virtues is an end in itself, since it leads to eudaimonia. For Kant, virtue is the moral strength of a person to fulfill his or her duty. He describes virtue as a “moral determination” that allows us to follow the moral law despite temptations and difficulties.
Thus, we can argue that Kantian good will fulfills a function similar to that of Aristotelian virtue. Both concepts refer to the disposition to act in accordance with reason and to seek the moral good. For Aristotle, virtue is the means by which we achieve happiness, and for Kant, good will is what makes an action morally good.
Furthermore, both philosophers agree that moral action should not be motivated by selfish interests or sensible desires. Aristotle, in his theory of virtue, argues that virtuous action is one that is performed for its own sake, and not because of external rewards. Kant, in turn, argues that morality requires that actions be performed out of duty, and not out of personal inclinations.
V. The Ultimate End: Eudaimonia and the Highest Good
Both Aristotle and Kant recognize the existence of an ultimate end or supreme good. For Aristotle, the ultimate end is eudaimonia, which he defines as the exercise of reason in accordance with virtue. Eudaimonia, as a state of living well, is achieved through the practice of virtues throughout life. This concept, it is reiterated, is central to Aristotelian ethics, since all moral action is oriented towards the achievement of this supreme good.
Kant also postulates the existence of a supreme good, developing the concept in a more complex way. For him, the supreme good is the combination of virtue and happiness. In his Critique of Practical Reason, Kant argues that the supreme good can only be achieved if virtue is rewarded with happiness. Even giving primacy to virtue over happiness by stating that morality requires us to seek virtue, and happiness should be seen as a fair but not guaranteed consequence of virtue; Kant takes up Aristotle’s idea of exercising reason in accordance with virtue, in the pursuit of happiness.
In his work, Kant recognizes that there is no guarantee that virtue will lead to happiness in the empirical world. Therefore, he postulates the need for the immortality of the soul and the existence of God to ensure that virtue is rewarded with happiness. In this sense, Kant’s supreme good can be seen as an evolution of the Aristotelian concept of eudaimonia, inserted into a distinct metaphysical framework, in which the complete realization of happiness is not guaranteed in this life, but in a transcendental context.
Both philosophers agree that reason and virtue are fundamental to the moral life, and that morality is directly connected to the idea of an ultimate end.
VI. Happiness and Morality: A Complex Connection
The relationship between happiness and morality is one of the most fascinating topics in the comparison between Aristotle and Kant. For Aristotle, happiness (eudaimonia) is the supreme end of human life and can only be achieved through virtue. The practice of virtue is not just a means to achieve happiness; the virtuous life itself is the happy life. Happiness, therefore, is intrinsically linked to morality, and the morally virtuous life is the truly happy life.
Kant, in turn, reinterprets this relationship in a significant way. In his theory, happiness cannot be the foundation of morality. For him, to act morally is to fulfill one’s duty out of respect for the moral law, and not with the aim of achieving happiness. Kant believes that the pursuit of happiness, as an empirical desire, is subject to contingency and cannot serve as a solid basis for morality. He states: “Morality is not the doctrine of how we are to make ourselves happy, but of how we are to make ourselves worthy of happiness” (Kant, 2003, p. 98).
However, Kant acknowledges that there is a connection between virtue and happiness, albeit an indirect one. He argues that if we follow moral duty, we should expect virtue to be rewarded with happiness, even if that reward is not guaranteed in this life. The idea that virtue deserves happiness is present in Kant’s notion of the “highest good,” in which happiness must be proportionate to virtue, but this proportionality can only be guaranteed by divine intervention. Thus, while happiness cannot be the direct goal of morality, it still plays an important role in the Kantian framework.
We can see a continuity between the ethics of Aristotle and Kant on this issue, as both agree that virtue is essential to the moral life and that there is a relationship between virtue and happiness. However, Kant modifies this relationship, arguing that happiness is not a goal to be directly pursued, but a just reward for virtue. Aristotle sees happiness as inseparable from virtue and the moral life. For him, to be virtuous is, by definition, to be happy. For Kant, in short, being virtuous makes the individual worthy of happiness, even if the achievement of happiness requires transcending mere empirical experience.
VII. Kant as a Revival of Aristotelian Ethics
Based on the previous discussions, we can conclude that Kantian ethics can be seen as a dialectical resumption of Aristotelian ethics. Although Kant rejects the idea that happiness can be the foundation of morality, he preserves many of the central elements of Aristotle’s ethics, such as the role of reason, the importance of virtue, and the connection between morality and an ultimate end. Kant reformulates these concepts to adapt them to his own philosophical project, focusing on moral duty and pure reason as the central guides of moral action.
By reorienting ethics around the concept of duty and the categorical imperative, Kant offers a solution to the problem of the contingency and subjectivity of notions of happiness. However, he still maintains an implicit teleological vision, by proposing the highest good as the ultimate goal of morality, in which virtue and happiness are reconciled.
Thus, despite subtle differences, we can see Kant as someone who revisits and expands Aristotle’s ethics, adjusting it to the philosophical demands of his time. Kant incorporates Aristotle’s emphasis on reason and virtue, but gives these concepts a new orientation, placing moral duty and universal law as the central elements of his ethics. In this way, it is argued that Kantian ethics should not be seen as a rejection of Aristotelian ethics, but as a dialectical continuity, in which the same principles are reinterpreted in light of new philosophical questions.
REFERENCES
ARISTÓTELES. Ética a Nicômaco. Tradução de Antonio de Castro Caeiro. Lisboa: Imprensa Nacional-Casa da Moeda, 1998.
KANT, Immanuel. Fundamentação da Metafísica dos Costumes. Tradução de Paulo Quintela. Lisboa: Edições 70, 2003.
KANT, Immanuel. Crítica da Razão Prática. Tradução de Valério Rohden e Guido Antônio de Almeida. São Paulo: Martin Claret, 2002.
