Classical German Philosophy belongs to the heritage of the European philosophical tradition, in which philosophical knowledge is defined as an epistemological reflection. Philosophy reflects on scientific knowledge to demonstrate its possibility. Thus objective knowledge is defined as a system whose principle is subjectivity. Since the 19th century, this concept of knowledge has been questioned as has subjectivity as such. Since then, philosophy in Germany has departed from comprehensive reflection and turned towards matters of detail or issues of application. In this paper I argue that the trend of skepticism about knowledge in modern German philosophy is associated with the radical social upheavals of modernity, but without being accompanied by a critical understanding of these upheavals. The first task is to reconstruct the classical concept of knowledge as it appeared in German philosophy, including its crucial relation to scientific knowledge and to history. The second task is to engage with the observation that this tradition of thought is in danger of being lost today. I will point out the role which the linguistic turn in philosophy has played and the means of deconstructing it.