On the Genealogy of Morals, sometimes translated as On the Genealogy of Morality, consists of three essays, each of which questions the value of our moral concepts and examines their evolution.

The first essay, “‘Good and Evil,’ ‘Good and Bad,’” examines the evolution of two distinctive moral codes. The first, “knightly-aristocratic” or “master” morality, comes from the early rulers and conquerors, who judged their own power, wealth, and success to be “good” and the poverty and wretchedness of those they ruled over to be “bad.” Nietzsche associates the second, “priestly” or “slave” morality, primarily with the Jews. This morality originates with priests, who despise the warrior caste and condemn their lustful power as evil, while calling their own state of poverty and self-denial good. This slave morality turns master morality on its head. Driven by a feeling of ressentiment, or resentment, slave morality is much deeper and more refined than master morality. Its crowning achievement is Christianity: Christian love is born from hatred. While slave morality is deeper and more interesting than the casual self-confidence of the masters, Nietzsche worries that it has rendered us all mediocre. Modern humans, who have inherited the mantle of slave morality, prefer safety and comfort to conquest and risk. The slave morality of the priestly caste focuses the attention on the evil of others and on the afterlife, distracting people from enjoying the present and improving themselves.

Nietzsche illustrates the contrast between the two kinds of morality by reference to a bird of prey and a lamb. Nietzsche imagines that the lambs may judge the birds of prey to be evil for killing and consider themselves good for not killing. These judgments are meaningless, since lambs do not refrain from killing out of some kind of moral loftiness but simply because they are unable to kill. Similarly, we can only condemn birds of prey for killing if we assume that the “doer,” the bird of prey, is somehow detachable from the “deed,” the killing. Nietzsche argues that there is no doer behind the deed, taking as an example the sentence, “lightning flashes.” There is no such thing as lightning separate from the flash. Our assumption that there are doers who are somehow distinct from deeds is simply a prejudice inspired by the subject–predicate form of grammar. Slave morality detaches subject from predicate, doer from deed, and identifies the subject with a “soul,” which is then liable to judgment. While slave morality is definitely dominant in the modern world, Nietzsche hopes that master morality will have a resurgence.

In the second essay, “‘Guilt,’ ‘Bad Conscience,’ and the Like,” Nietzsche suggests that our concept of guilt originally had no moral overtones, identifying a similarity in the German words for guilt and debt. A person in debt was “guilty” and the creditor could make good on the debt by punishing the debtor. Punishment was not intended to make the debtor feel badly but simply to bring pleasure to the creditor. Punishment was cruel but cheerful: there were no hard feelings afterward. A society with laws is like a creditor: when someone breaks the law, they have harmed society and society can exact punishment. The concept of justice in effect takes punishment out of the hands of individuals by claiming that, in a society, it is not individuals but laws that are transgressed, and so it is the laws, not individuals, that must exact punishment. Reflecting on the many different purposes punishment has served over the ages, Nietzsche observes that all concepts have a long and fluid history where they have had many different meanings. The meanings of concepts are dictated by a will to power, where concepts are given meanings or uses by the different wills that appropriate them.

Nietzsche identifies the origin of bad conscience in the transition from hunter–gatherer to agrarian societies. Our violent animal instincts ceased to be useful in a cooperative society, and we suppressed them by turning them inward. By struggling within ourselves, we carved out an inner life, bad conscience, a sense of beauty, and a sense of indebtedness to our ancestors, which is the origin of religion. At present, we direct our bad conscience primarily toward our animal instincts, but Nietzsche urges us instead to direct our bad conscience against the life-denying forces that suppress our instincts.

The title of the third essay poses the question, “What Is the Meaning of Ascetic Ideals?” Why have people from various cultures pursued an ascetic life of self-denial? Nietzsche suggests that asceticism enhances the feeling of power by giving a person complete control over him- or herself. In many cases, then, asceticism is ultimately life affirming rather than life denying. Ascetic ideals manifest themselves differently among different kinds of people. A sort of philosophical asceticism leads philosophers to claim that the world around them is illusory. This is one way of looking at things, and Nietzsche applauds looking at matters from as many perspectives as possible. There is no single right way to look at the truth, so it’s best to be flexible in our viewpoints.