Why did Georg Wilhelm Friedrich Hegel challenge the separation of logical form from substance?

Georg Wilhelm Friedrich Hegel challenged the separation of logical form from substance because he viewed this division as a fundamental error that prevented philosophy from grasping the true nature of reality.12

For Hegel, the speculative point of view must transcend separate perspectives to understand the "Absolute"—the all-embracing totality of reality—as a conscious agent or Spirit, rather than merely as a static, underlying substance. He famously declared that "substance must become subject," meaning that the rational structure of the world is not an abstract, external method, but the actual, living development of the Absolute Spirit.12

By treating logical form as something extraneous to content, modern philosophers—particularly those following Immanuel Kant—failed to account for the intrinsic nature of objective reality, leading to "subjectivism". Hegel argued that his logic was not a formal, empty structure, but the essential process through which reality realizes itself. Consequently, he sought to reconcile ontology and epistemology, asserting that the rational is the real and that truth is found in the "Whole".2314