Aristotle and Niccolo Machiavelli agree that human nature predisposes men to serve their own interests, and that we need government to control our innate desires, and yet the two disagree on the origin of government and its purpose. Aristotle argues that man is political by nature due to speech. Through speech, men develop a common moral determination for what is just and unjust, and naturally form political societies in the acquisition of virtue. Although Aristotle's government operates in the pursuit of human excellence, it is based on an optimistic notion, that men will choose and continue to seek moral advancement. Machiavelli adopts a more practical perspective not on the moral capability of men, but on the role morality will actually play in daily life. Machiavelli argues that extraordinary men founded political societies, and that any government's primary purpose should be to preserve itself. .
In his book "Politics," Aristotle begins his work by outlining his ideas concerning human nature and the formation of what he calls political associations. In his pursuit to validate political societies, Aristotle argues that these associations originate out of natural necessity. The unity between a man and woman is Aristotle's evidence that associations form in a state of nature. This natural association of a family unity provides Aristotle support in his claim that, "the state is the creation of nature, and man is by nature a political animal" (Politics Book I.ii.). Through the creation of political associations men become political animals in part, however this social tendency is not what essentially classifies man as a political animal according to Aristotle. Man is not simply another gregarious species, because man is endowed with the power of speech. .
This distinction between man and other animals is vital to Aristotle's argument that man is different, that he is political.