The term transcendental philosophy includes philosophies, systems, and approaches that describe the fundamental structures of being, not as an ontology (Theory of Being), but as the framework of emergence and validation of knowledge of being.
Overview
"Transcendental" is a word derived from the scholastic, designating there the extra-categorical attributes of beings, and for Immanuel Kant it is the investigation on the conditions of possibility of something, e.g., of knowledge, that is the form of knowledge. By examining the transcendental approaches of the conditions of knowledge previous (a priori) to any experience of the subject, metaphysics, as a fundamental and universal theory, turn out to be an epistemology. Transcendental philosophy, consequently, is not considered a traditional ontological form of metaphysics.
Immanuel Kant, the first to coin the term, laid the groundwork in the Critique of Pure Reason to the edification of a transcendental philosophy. He defines the general problem of this philosophy by the question "how synthetic a priori judgments are possible?". While the Critique of Pure Reason provides an analysis only of the "fundamental concepts", a full transcendental philosophy would require "an exhaustive analysis of all of human cognition a priori".
Contemporary transcendental philosophy is developed by German philosopher Harald Holz with a holistic approach. Holz liberated transcendental philosophy from the convergence of neo-Kantianism, he critically discussed transcendental pragmatism and the relation between transcendental philosophy, neo-empiricism and the so-called postmodernism.