Why does Aristotle regard Politics as the 'Master Science' ?

Why does Aristotle regard Politics as the 'Master Science' ?

Unlike Plato, for whom knowledge of philosophy, ethics, education, psychology and sociology all were parts of philosophy, Aristotle differentiated branches of knowledge, viz. physics, biology, meteorology, natural history, aesthetics, rhetoric, poetics, logic, metaphysics, ethics and politics and wrote separate treatises on these subjects.
Aristotle paved the way for their independent development.
Aristotle laid the foundations of the science of politics and produced his famous work 'Politics'.
Aristotle regards politics as the 'master science' or 'master art' for following reasons:-

Purpose (end) of the human life is to secure good and happy life, which is the prime goal of politics.
End of all branches of knowledge ends up in politics. Examples:-

Physical exercise gives us some enjoyment but ultimate goal is to improve our health, which promote good life which is the end of politics.
Eficient household management is designed to increase wealth. Wealth is a means to good life which comes within the purview of politics.
The art of bridle-making is meant to raise efficiency of horse-riding. Significance of horse-riding lies in showing chivalry in the battlefield and winning the war. Victory in war is meant to glorify the state which is the prime concern of politics.

The ends of all other sciences and arts like medicine, military science or economics are concerned with securing good life in different spheres of human life. Taken together they tend to evolve a comprehensive view of good life which represents the end of politics. Hence all other sciences and arts are subordinate to the science of politics.
Politics is not only concerned with the duties of all citizens (like Plato's), it also comprehends all social relations involving the use of authority. It involves husband's control over wife, father's control over children, master's control over slaves, methods of education, worship of gods, celebration of festivals, organization of sports, military training, etc. Husband's, father's or master's authority involved personal or despotic rule while a statesman's authority involved the rule according to the principles of politics.

What was the political scenario in Greek in the times of Aristotle ?

The number of people associated with politics during those days was very small.
Only 'freemen' had any political rights which entitled them to participate in public decision-making.
The number of freemen was not more than one-third of the total population.
Slaves or aliens had no role in politics.
Even among freemen, women had no role in the decision-making process.

Does Aristotle's notion of politics correspond to the modern view of politics?

Aristotle's notion of politics does not correspond to the modern view of politics.
Today under normal conditions political rights are extended to all the members of a political community, but politics is concerned with a specific aspect of social life; it cannot be regarded as an instrument of total control of social life as Aristotle had postulated.
Many aspects of social life, such as religion, education, art and literature, etc. are now deemed to be autonomous and sought to be segregated from politics.
Hence Aristotle's notion of political authority is not fit for application to the modern society.