This chapter is a good example of the fluidity of Aristotle’s thought, and of some difficulties in his view of slavery. First he again distinguishes mastership from other forms of rule, and then suggests that the essence of being a master lies in being a certain sort of person (i.e. rational, wise, etc.), not in having knowledge of how to use slaves. This curious point seems to be made because, as he notices, some fairly humble knowledge, which we are tempted to call a ‘master’s’ knowledge, may be possessed and exercised by those who are not masters, e.g. overseers (who might be slaves themselves): how then can it be the essence of mastership? On the other hand it is difficult to see how one can be a master simply by being of a certain character, without having an active relationship, presumably of command, with one’s slaves. Aristotle could perhaps have distinguished between (a) the knowledge, characteristic of and peculiar to a master, of the ‘ends’ of a slave’s work, in some wide context, and (b) the technical knowledge, possessed by overseers also, of the work itself. But he does not do this, and seems to feel in something of a dilemma. In this chapter we hear him ‘thinking off the top of his head ’.
1255b16 From all this it is clear that there is a difference between the rule of master over slave and the rule of a statesman.1 All forms of rule are not the same though some say that they are.1 Rule over naturally free men is different from rule over natural slaves; rule in a household is monarchical, since every house has one ruler; the rule of a statesman is rule over free and equal persons.
1255b20 A man is not called master in virtue of what he knows but simply in virtue of the kind of person he is; similarly with slave and free. Still, there could be such a thing as a master’s knowledge or a slave’s knowledge. The latter kind may be illustrated by the lessons given by a certain man in Syracuse who, for a fee, trained house-boys in their ordinary duties; and this kind of instruction might well be extended to include cookery and other forms of domestic service. For the tasks of the various slaves differ, some being more essential, some more highly valued (as the proverb has it ‘slave before slave, master before master’).2
1255b30 All such fields of knowledge are the business of slaves, whereas a master’s knowledge consists in knowing how to put his slaves to use; for it is not in his acquiring of slaves but in his use of them that he is master. But the use of slaves is not a form of knowledge that has any great importance or dignity, since it consists in knowing how to direct slaves to do the tasks which they ought to know how to do. Hence those masters whose means are sufficient to exempt them from the bother employ an overseer to take on this duty,3 while they devote themselves to statecraft or philosophy. The knowledge of how to acquire slaves is different from both these,4 the just method of acquisition, for instance, being a kind of military or hunting skill.5
So much may suffice to define master and slave.