How the more extreme forms of domination and submission oriented dynamics acquired the terminology “Master/slave” is an odd question at first glance, and one related to another form of terminology, that of “Owner/property”.
A slave, defined by being-owned, would by definition have an owner. One who owned a human being would by definition have a slave, owning simple “property” would not distinguish one from any other in our current society. Masters in various areas of endeavour might have servants, novices, acolytes, initiates, apprentices, etc. But in the specific area of consensual slavery the slave’s owner appropriates the designation “Master”. Seemingly in reaction to the ability and responsibility mastery requires, some in domination/submission dynamics opt out of the issue of what mastery entails, preferring to return to simple ownership, but the simulaneous reduction of human property (“slave”) to just “property” signals a felt lack, as if owning a human being without mastery is somehow inappropriate.
Consensual slavery has multiple defining features, but one of the principle features is a vow of obedience that overrules further need for consent, in most cases perpetual, at least in intention. Perpetual vows of obedience are found in a number of other areas of human endeavour, but are most associated with the religious life. Within many religious orders a vow of obedience to the order is prescribed. While it is unusual today, vows of obedience to a particular person were at one time also common within Christianity as in other religions.
The justification for vows of obedience within specifically Christian theology stemmed from the limited perspective available to any given individual, together with the notion that community ameliorated that limitation and provided a brake on unconstrained and potentially mistaken willing by the individual.
Will as Will to Power, in the consummation of metaphysics and therefore Christianity itself, however, is the term for the essence of being itself, rather than a specific faculty of a specific being. As the essence of being itself the slave’s being is as fully Will to Power as the Owner’s. Rather than ameliorating the expression of Will to Power, the being of the community, religious or otherwise, is also Will to Power. A vow of obedience could not in post Nietzschean terms accomplish any constraining of the Will to Power but would simply make the perspective panoramic, and as panoramic all the more perspectival.
A vow of obedience, as central to the slave’s being-a-slave, and hence the slave’s expression of Will to Power, serves two other purposes. First the vow is a shield against the tempting, in particular the most tempting itself. Second it is the focus for the more understanding and creative expression of that will demanded by its continuing alignment with the will of the Master.
It is in the radicality of the demand of obedience that it functions as a shield against the tempting. “The most tempting itself” is an odd phrase at first – temptation is often conflated with desire, yet in a sense it opposes and frustrates the pursuit of that which is most desired itself. Temptation diverts from the pursuit of desire as much as from the pursuit of perfection, or any other particular pursuit. As the “most” tempting fundamental temptation is something we always find ourselves in in advance. Radical obedience, in either expectation or fulfillment, opposes the most tempting in an essential way because it is an extraordinary expectation, and an extraordinary thing to attempt. “The most tempting”, the founding temptation in which we always find ourselves immersed is essentially the temptation of the mediocre, the averageness of everyday understanding and levelling off any distinctions that might threaten that tranquillizing mediocrity of everydayness itself.
Expecting this kind of vow implictly requires a sense of one’s own unique abilities, a sense that develops with mastery of those abilities itself, a sense that breaks and continually re-breaks the temptation towards a tranquilizing common mediocrity. Consenting to such a vow requires an honouring of the uniqueness of the Master’s abilities that accomplishes the same severing from the temptation to mediocrity.