Portrait of Aristotle

Aristotle insists that man is either a political animal (the natural state) or an outcast like a “bird which flies alone” (4thC BC)

Found in: The Politics vol. 1

In his Politics, Aristotle believed man was a "political animal" because he is a social creature with the power of speech and moral reasoning:

Philosophy

Hence it is evident that the state is a creation of nature, and that man is by nature a political animal. And he who by nature and not by mere accident is without a state, is either above humanity, or below it; he is the ‘Tribeless, lawless, hearthless one,’ whom Homera denounces—the outcast who is a lover of war; he may be compared to a bird which flies alone.