康德以先验论(人为自然立法的现象学)论证知识的客观性和现象世界的实在性。海德格尔则认识到认识论意义的认识不具自存性,它还有更为深层的根基,即生存存在论,存在论层次的认识先于并高于认识论意义的认识。康德区分现象与本体主要为道德形而上学奠基,作为现象根基的本体理念乃不在之"在",此说耐人寻味。海德格尔则批评康德的本体论只关乎在者而非"在"。海德格尔终生追问"在",指出思对"在"的归属与谐响,从康德之"问"回归于"答",同时也强调"在"与表象之同一,克服康德超验形而上学。康德的问题是"先天综合如何可能",海德格尔的问题是"在是怎么一回事"。前者讲思对"在"的综合,后者讲思对"在"的应合,二者都是伟大心灵传达"在"之词语的杰作,其不同意味着时代之不同,其不同也标出不同之时代。

Kant establishes knowledge and phenomenal world with transcendentalism,while Heidegger holds that the epistemological cognition presupposes the ontological,and the letter is prior. Kant distinguishes phenomena from noumena for moral metaphysics,but in Heidegger's opinion,Kant's noumena are beings instead of being. Heidegger quests for being all his life and insits that thinking belong to being and stresses that representation is identified with being. For Kant the question is how possible synthetical judgments are prior,but for Heidegger the question is how it stands with being. Kant proclaims synthesis while Heidegger suggests answer. Their difference reflects that of time.