Transendental Turn And Existential Turn Of Epistemology--Re-understanding Of Epistemology In Existential Dimension

With Descartes"I think ,therefore I am " for the beginning , the epistemology turn has taken place in modern philosophy, namely before providing the ultimate truth of the world , investigate first the legitimacy of people's cognition that is regarded as the subject of reason . Only first question how people's cognition is possible, then human can use reason know world legally . Therefore, epistemology is to look for the foundation for science, that is critical investigating of cognitive ability which science must use .Because pre-Kant's epistemology's one-sided understanding of sensibility and reason as the two key elements of knowledge, the result causes empiricism moving towards Hume's scepticism and rationalism moving towards Leibniz-Wolff's dogmatism metaphysics system. Hume think sensal experience and rational reasoning cannot offer basis of legitimacy for cognition, so objectivity and general necessity of knowledge are not known where to begin.Kant starts with criticizing human's reason and investigates for the first time the possibility of cognition. Kant transforms empirical ego with transendental ego, empirical logic with transendental logic, establishes the key function of transendental apperception in forming knowledge. Meanwhile, it is possible for the creativity of transendental imagination for transendental schema to connect sense-data and understanding concepts. In this way, categories unify the intuition sensa-data through transandental schema, thus form knowledge. But because Kant insist "understanding cannot intuition and sensibility cannot think ", therefore his transendental subject seperates from transendental object .Being the thing-in-itself, transendental object go beyond the cognitive ability of transendental subject .Husserl setting up his own transendental intentionality structure through phenomenon reduction, he transendentalities Kant's transendental subject completely and finishes transendental turn of epistemology. Transendental epistemology guarantees general necessity of cognition through transendenal structure of consciousness, it set up the prerequisite of cognition possibility on transendenal logic function of thinking. But because of objectivity uncompleted, transendenal logic experience remained, transendenal ego in a difficult theory position, transendental epistemology is unable to reach that supreme idea and essence existence. And due to the cognitive mode of thinking based on "I think ", its feature must set dyadic contrast between thinking and existing, subject and object , therefore it can not solve the problem of unifying thinking and being of epistemology.Heidegger starts the existential turn of epistemology in criticizing dogmatism of transendental philosophy and substantial essence of traditional metaphysics. He reveals the existential prerequisite of epistemology and understands epistemology again in the existence mode, regards the cognition as the real course of dasein "in the world". Heidegger thinks the traditional philosophy has confused being and entity which leads to forgetting the real meaning of being. The reason to cause this kind of situation is that subject regulate being as substance, but subjectivity as internalizion is opposite to object out of consciousness. All these cause existential covering of epistemology. To recover the real meaning of being ,we must start from dasein, namely personal existence. Only can dasein ruin internalizion,overcome subjectivity, that the meaning of being can be clarity and appear. Dasein is already not personal subjective cognition, but a being mode of "in the world", an existential understanding. Cognition is a mode of "in the world". Heidegger maintains investigating the meaning of being by regarding the person as entity, we should not set out from reality or "I think" like traditional epistemology. As dasein, person is a temporality being whose essence is time. In the horizone of temporality, dasein reaches being and holds the meaning of being during priori understanding of "being to...