What Is Political Philosophy? And Other Studies, The Free Press, 1959.  Reprint: University of Chicago Press, 1988.

Excerpt:

The meaning off political philosophy and its meaningful character are as evident today as they have been since the time when political philosophy first made its appearance in Athens. All political action aims at either preservation or change. When desiring to preserve, we wish to prevent a change to the worse; when desiring to change, we wish to bring about something better. All political action is, then, guided by some thought of better or worse. But thought of better or worse implies thought of the good. The awareness of the good which guides all our actions, has the character of opinion: it is no longer questioned but, on reflection, it proves to be questionable. The very fact that we can question it, directs us towards such a thought of the good as is no longer questionable— towards a thought which is no longer opinion but knowledge. All political action has then in itself a directedness towards knowledge of the good: of the good life, or the good society. For the good society is the complete political good.

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