How did Neo-Kantianism and positivism challenge Hegelianism?

In the second half of the 19th century, the influence of Hegelianism declined significantly in Germany, a shift driven largely by the rise of Neo-Kantianism and positivism.1

Neo-Kantianism

Neo-Kantianism emerged as a revival of Immanuel Kant’s philosophy, explicitly aiming to divert German thought away from the speculative idealism that characterized the Hegelian tradition. Thinkers like Otto Liebmann popularized the imperative "Back to Kant!" to move beyond what they viewed as a "positivistic morass" and the metaphysical excesses of Hegel’s system. By emphasizing Kant’s limitation of scientific knowledge to the sphere of phenomena, Neo-Kantians rejected the Hegelian claim that reason could attain "absolute knowledge" of essences or things-in-themselves.234

Positivism

Positivism challenged Hegelianism by rejecting metaphysics entirely, viewing it as incompatible with a scientific approach to knowledge. While Hegelianism sought to provide a unitary, dialectical explanation for all of reality, positivism focused on empirical observation. This rejection of speculative philosophy forced a re-evaluation of the Hegelian heritage, contributing to its decline as the intellectual climate shifted toward empirical and political realism.215