Liberal philosophy emerged from enlightenment philosophy, which was adopted by the bourgeois during their ascension over hundreds of years to become the ruling class.

One of the primary tasks of the bourgeois, and the function of enlightenment philosophy to them, was to erode the power of the church, and eventually the monarchy, over the masses. This period, which developed at different times throughout Europe, is followed by "the ~~encirclement~~ enclosure" in which peasants who had lived self sufficiently for hundreds, maybe over a thousand years, were forced off the land and forced into the towns and cities on the outskirts, forcing people to travel extreme distances, most often on foot, to work the land for destitution wages they once worked and subsisted on for free and in peace.

Liberals are rationalists, which means that anything that exists in nature must be intellectually comprehensible. They believe that in order for a social institution to exist, it must be internally logically consistent.

Engels describes it this way in Anti-Duhring:

The great men, who in France prepared men’s minds for the coming revolution, were themselves extreme revolutionists. They recognized no external authority of any kind whatever. Religion, natural science, society, political institutions – everything was subjected to the most unsparing criticism: everything must justify its existence before the judgment-seat of reason or give up existence. Reason became the sole measure of everything. It was the time when, as Hegel says, the world stood upon its head.

Liberalism obscures class character, since liberalism espouses that all "men" are equal. This is, of course true in nature, but class rule introduces the fundamental contradiction that places some above another. This is the source of liberal blind idealism, and resolves by subordinating all social contradiction to individual responsibility/social contract theory. Most of the criticisms by leftists that blame individual liberals for their wrongheadedness and exclude criticisms of structural hegemony , also fall for this confusion.

From there its a function of hegemony. The intellectual/media class political attack dogs of the ruling class perform the "unsparing criticism" of their forebears, and the educated middle class is conditioned to perform the ideology.