Liberal thought had existed in the Milky Way Galaxy for a long time, and its roots lay in the Galactic Republic's more than 25,000 years of rule.
Yet of those 25,000 years, 24,000 had merely established the Galactic Republic's legitimacy and reasonableness in the eyes of the people. In other words, people naturally assumed that the Milky Way Galaxy ought to be ruled by the Galactic Republic.
Liberalism truly began to flourish after the Rusan Reforms more than a thousand years ago. In those reforms, the Galactic Republic abandoned nearly all its military power and proclaimed that it had brought freedom, equality, and prosperity to the Milky Way Galaxy.
Equality and prosperity were naturally nonexistent, but freedom, on closer consideration, really did exist. Most of the time, the Galactic Republic's weak central government had neither the interest nor the time to govern the planets of the Outer Rim and Mid Rim.
Moreover, the Milky Way Galaxy had no particularly powerful external enemies at the time. At most, there were interstellar pirates and criminal organizations. Though evil, they were incapable of shaking the foundations of the Galactic Republic. Thus, aside from being exploited by the Galactic Republic's Mega-corporations, most Mid Rim and Outer Rim planets truly remained in a state of autonomy where no one bothered with them.
Furthermore, the Galactic Republic's parliamentary system gave those numerous backward planets a stage on which they could bicker loudly in the Republic Senate and make their voices heard. And so long as core interests were not involved, the true elites of the Core Worlds were quite willing to play this game of democracy with them.
Thus, although those planets suffered terribly under the exploitation of Mega-corporations, their people often blamed the Mega-corporations themselves. They instead identified strongly with the Galactic Republic. Or rather