Aristotle argues in his book 'The Politics' that the city is a political partnership that exists only because it needs to be self sufficient, but also exists for the sake of living well (Aristotle, Politics, Book 1, page 1). He also believes that man is by nature a political animal since he has the ability to communicate ' the state is a creation of nature, and that man is by nature a political animal' (Aristotle, Politics, Book 1, page 3). As far as slavery, he argues that natural slaves are those who are able to perceive reason but do not have it and so he feels that such people should be ruled. He feels that mastery is rule over slaves, but political rule is rule over free and equal persons.
As far as citizenship is concerned, Aristotle views a citizen as one who shares in the decision-making process and holds office. Therefore citizenship is essentially democratic, but the notion of citizenship in practice must differ according to the nature of the regime. However, a citizen is usually considered to be anyone whose parents are citizens (Book III, page 5). He believes the citizens will be exclusively the ruling class, which will rule and be ruled in turn such that the young will be soldiers and the old will rule. Citizens in democracies rule and are ruled in turn.
Aristotle argues that the virtue of a good man and an excellent citizen may be different, because the virtue of a citizen is determined with a view to the preservation of the regime. As long as the actual regime is close enough to the best regime, the virtue of a good man and an excellent citizen can coincide 'If the state cannot be entirely composed of good men, and yet each citizen is expected to do his own business well, and must therefore have virtue, still inasmuch as all the citizens cannot be alike, the virtue of the citizen and of the good man cannot coincide'(Book III page 7). The best regime corresponds to the best way of life which is living...