Hans Morgenthau on International relations

“We must distinguish between military and political power. Political power is a psychological relation between those who exercise it and those over whom it is exercised. It gives the former control over certain actions of the latter through the influence which the former exert over the latter's minds. That influence may be exerted through orders, threats, persuasion, or a combination of any of these.”

“Political realism is aware of the moral significance of political action. It is also aware of the ineluctable tension between the moral command and the requirements of successful political action. And it is unwilling to gloss over and obliterate that tension and thus to obfuscate both the moral and the political issue by making it appear as though the stark facts of politics were morally more satisfying than they actually are, and the moral law less exacting than it actually is.”

“The struggle for power is universal in time and space and is an undeniable fact of experience. It cannot be denied that throughout historic time, regardless of social, economic and political conditions, states have met each other in contests for power. Even though anthropologists have shown that certain primitive peoples seem to be free from the desire for power, nobody has yet shown how their state of mind can be re-created on a worldwide scale so as to eliminate the struggle for power from the international scene. … International politics, like all politics, is a struggle for power. Whatever the ultimate aims of international politics, power is always the immediate aim.”

“Political realism believes that politics, like society in general, is governed by objective laws that have their roots in human nature. In order to improve society it is first necessary to understand the laws by which society lives. The operation of these laws being impervious to our preferences, men will challenge them only at the risk of failure. V`Realism, believing as it does in the objectivity of the laws of politics, must also believe in the possibility of developing a rational theory that reflects, however imperfectly and one-sidedly, these objective laws. It believes also, then, in the possibility of distinguishing in politics between truth and opinion — between what is true objectively and rationally, supported by evidence and illuminated by reason, and what is only a subjective judgment, divorced from the facts as they are and informed by prejudice and wishful thinking.”