Existentialism. The rejection of DESCARTES. "I am, therefore I think" - We exist. There is no need for proof. [Anti-POPPER].
KANT and "The Critique of Pure Reason" [1781] Existence has no purpose, it is just necessary; a pre-condition of consciousness. As we exist, we constantly change and mutate. Our consciousness is subjective (based on the moods of the moment) and aposteriori in nature.
HUSSERL and Phenomenology (consciousness without reference to external). "Psychology from an Empirical Standpoint" [1874] The metaphysical view that our essence is embodied. Abolition of mind and matter. Instead, mind over matter. Phenomena is presented to us through consciousness as a "thing in itself" (independent).
HEIDEGGER - "Being and Time" [1927] saw the end of the metaphysical outlook. He disagreed with HUSSERL - objects are not independent from mind, instead, they are a refection of consciousness. Objects exist only in the mind. Therefore, there can be no "absolute truth" DESCARTES - No difference between dream and reality.
DASEIN: "way of being"/"being there" (German) Reflective of the perceiver's mood. HEIDEGGERS PROJECT - to live subjectively; an 'authentic life'. Rejection of all philosophy since SOCRATES. ROUSSEAU - to break free from industrial chains.