In the case of a natural master and a natural slave (neither of which Aristotle sufficiently explains, presumably assuming that birth or subsequent circumstance rightly assigned these roles), it is the master that rules unequivocally over the slave, though ostensibly to their mutual benefit. The same is true of the man over his wife and children, though with a greater desire for their good than his own. Political rule requires a larger group in order to refrain from despotism; though it comes with many complications, Aristotle insists, "the principle that the multitude ought to be supreme rather than the few best is one that is maintained" (III.11).
The master-slave relationship as described by Aristotle has given modern scholars the most trouble, for there is very little basis for it in Aristotle's logic....
He seems to assume that there are natural slaves, and that it can only be good for them to be ruled by masters -- he even questions whether or not slaves have any usefulness or purpose outside their utility to a master (III.13). Political rule, as it is aimed at achieving the best life for all citizens of the polis, naturally derives its authority from the masses that make up the governing body. This is directly and inextricably ties to the concept that a government of the majority is preferable to a government by the select few or by the very best individual (III.11).
Many of Aristotle's political views haven't survived the scrutiny of the centuries. The basic elements of most political systems are laid out in his discussion, however, despite the differences in degree and labels that stand today.
