Master–slave morality is a central theme of Friedrich Nietzsche's works, in particular the first essay of On the Genealogy of Morality. Nietzsche argued that there were two fundamental types of morality: 'Master morality' and 'Slave morality'. Slave morality values things like kindness, humility, and sympathy, while master morality values pride, strength, and nobility. Master morality weighs actions on a scale of good or bad consequences (i.e. classical virtues and vices, consequentialism), unlike slave morality which weighs actions on a scale of good or evil intentions (e.g. Christian virtues and vices, Kantian deontology). Master–slave morality does not take into account human emotions.
For Nietzsche, a particular morality is inseparable from the formation of a particular culture, meaning that a culture's language, codes and practices, narratives, and institutions are informed by the struggle between these two moral structures (see valuation).
Nietzsche defined master morality as the morality of the strong-willed. Nietzsche criticizes the view, which he identifies with contemporary British ideology, that good is everything that is helpful, and bad is everything that is harmful. He argues proponents of this view have forgotten the origins of its values, and is based merely on a non-critical acceptance of habit: what is useful has always been defined as good, therefore usefulness is goodness as a value. He continues explaining, that in the prehistoric state, "the value or non-value of an action was derived from its consequences," but ultimately, "There are no moral phenomena at all, only moral interpretations of phenomena." For strong-willed men, the 'good' is the noble, strong, and powerful, while the 'bad' is the weak, cowardly, timid, and petty.
The essence of master morality is nobility. Other qualities that are often valued in master morality are open-mindedness, courage, truthfulness, trust, and an accurate sense of one's self-worth. Master morality begins in the 'noble man' with a spontaneous idea of the good, then the idea of bad develops as what is not good. "The noble type of man experiences itself as determining values; it does not need approval; it judges, 'what is harmful to me is harmful in itself'; it knows itself to be that which first accords honour to things; it is value-creating." In this sense, the master morality is the full recognition that oneself is the measure of all moral truths. Insofar as something is helpful to the strong-willed man, it is like what he values in himself; therefore, the strong-willed man values such things as good, because they aid him in a lifelong process of self-actualization through the will to power.