It is a truism that the structure of a society is basically determined by its technology. Not in an absolute sense—there may be totally different cultures using identical tools—but the tools settle the possibilities: you can't have interstellar trade without spaceships. A race limited to one planet, possessing a high knowledge of mechanics but with all its basic machines of commerce and war requiring a large capital investment, will inevitably tend toward collectivism under one name or another. Free enterprise needs elbow room.
Automation made manufacturing cheap, and the cost of energy nose-dived when the proton converter was invented. Gravity control and the hyperdrive opened a galaxy to exploitation. They also provided a safety valve: a citizen who found his government oppressive could usually emigrate elsewhere, which strengthened the libertarian planets; their influence in turn loosened the bonds of the older world.
Interstellar distances being what they are, and intelligent races all having their own ideas of culture, there was no universal union. Neither was there much war: too destructive, with small chance for either side to escape ruin, and too little to fight about. A race doesn't get to be intelligent without an undue share of built-in ruthlessness, so all was not sweetness and brotherhood—but the balance of power remained fairly stable. And there was a brisk demand for trade goods. Not only did colonies want the luxuries of home, and the home planets want colonial produce, but the old worlds themselves had much to swap.
Under such conditions, an exuberant capitalism was bound to strike root. It was also bound to find mutual interests, to form alliances, and settle spheres of influence. The powerful companies joined together to squeeze out competition, jack up prices, and generally make the best of a good thing. Governments were limited to a few planetary systems each, at most; they could do little to control their cosmopolitan merchants. One by one, through bribery, coercion, or sheer despair, they gave up the attempt.
Selfishness is a potent force. Governments, officially dedicated to altruism, remained divided; the Polesotechnic League became a super-government, sprawling from Canopus to Polaris, drawing its membership from a thousand species. It was a horizontal society, cutting across all political and cultural boundaries. It set its own policies, made its own treaties, established its own bases, fought its own minor wars—and, in the course of milking the Milky Way, did more to spread a truly universal civilization and enforce a lasting Pax than all the diplomats in the galaxy.
But it had its troubles.
—"Margin of Profit"