Postmodern liberals still believe Schleiermacher’s dictum. Situational ethics, moral relativism, and the cultural relativism of truth claims are based on the idea that the truth must be discovered subjectively.
The relativism of truth claims made it possible for idealist philosopher Georg Hegel (1770-1834) to invent his own cosmos. He argued that the truth changes over time in accordance with his theory of historicism. However, historicism is logically impossible.
No cosmos can exist in which every individual invents his own truth claims. Historicists believe that each generation must subjectively discover its own truth. However, a generation seeking truth subjectively could never agree on its own truth claims because the subjective search for truth requires each person to invent his own truth. Hegel could not invent his own cosmos without implicitly inviting everyone to invent their own cosmos. Any society that invites its people to do this will shatter into fragments and collapse.