We have seen that, for Plato, Hobbes and Locke in their different ways, any authority that morality may have for us, and so any authority which “rights” may have for us, consists in its unchanging and independent status and in its essentially rational or consistent nature, foundation or content, however that may be known. In addition, whichever of the detailed conclusions of these philosophers we accept, reason has a capacity to motivate us. It is now time to question the presupposed “independence” of morality or reason that these philosophers use in their various approaches.

Plato's theory of human motivation essentially involves motivation on the basis of the degree of knowledge of what is good. A weakness in this for present-day philosophers is that it seems appropriate to respond in the following way: knowing what is truly good does not ensure that one will act or govern in terms of that knowledge, for one may not desire to do what is good. Rational self-mastery is not just a matter of reason ensuring that we have knowledge of the good; it is also a matter of reason ensuring that we have the will to do what is good.

Hobbes presents an alternative: it is not Platonic abstract ideas that are real and that motivate us, but material things. As human beings we are made of material objects, the motions of which cause changes in us, and these form our own mental experiences, which include our desires.