This illustrates both the strengths and weaknesses of ethics of duty.
This approach to ethics effectively counters a specific kind of evil, which seeks to justify immoral actions by claiming they are consistent with duty. However, this ethical approach appears powerless against a second type of evil, which openly acknowledges that its immoral actions are contrary to duty but asserts that duty itself has no value, claiming instead that what is valuable is disregarding duty to pursue one's own interests.

The ethics of duty effectively demonstrates that the concept of duty is coherent and cannot be reduced to happiness or pleasure, preventing those who commit immoral acts from using duty as a justification. However, it is powerless against those who invoke an alternative concept, such as value, to judge and ultimately dismiss the notion of duty.

This criticism applies to all ethics of duty, meaning moral doctrines that view the foundation of morality as proving that duties exist or that commonly accepted moral rules are indeed duties.

The failure of ethics of duty does not necessarily indicate the failure of moral theory as a whole; perhaps a different approach that assigns an alternative meaning to morality could offer a clearer understanding of its foundation. Might we suggest that morality, rather than being about determining duty, is instead the search for what brings us happiness?

2/ It is not looking for what makes us happy

The question of the foundation of morality can take on a different meaning from merely investigating whether duties exist. Alternatively—and from an entirely different perspective—we might consider that founding morality means demonstrating that it enables us to achieve happiness.

We will refer to doctrines that advocate this perspective as 'ethics of happiness'—and once again, we will not attempt to determine whether utilitarianism, which naturally comes to mind, falls under this category.

Ethics of happiness effectively demonstrate that happiness is what people prefer and may even argue that the essence of duty is fundamentally tied to happiness or pleasure. However, evil can be viewed as the axiological position that asserts the true value lies in the disappearance of humanity and all human desires, including the fundamental desire for happiness. The fact that humans wish to be happy—or even that happiness is what they most desire—does not allow us to deduce that human existence itself has any inherent value.

Ethics of happiness, therefore, suffer from the same flaw as ethics of duty: they can only counter certain forms of evil. Ethics of happiness can counter egoism, effectively arguing that what benefits me most is for all people to be happy. Therefore, in pursuing my own happiness, I must also promote the general happiness of humanity.

However, while it may succeed in refuting egoism, it cannot counter a second kind of evil—one that acknowledges my happiness depends on the happiness of others but asserts that true value lies in the destruction of that happiness, and even of humanity itself.