Georg Hegel (1770-1831)
Perhaps the greatest of all the German idealists, Hegel, like Kant, thought that reality consisted of a fundamental unity that was rational in nature but unknowable in practice. But Hegel thought that if reality is rational then its ultimate structure can be revealed in the structure of our thought.
The fundamental structure of thought and logic, to Hegel, is dialectical in nature. That is, the human mind invariably moves from the thesis (i.e., current understanding of reality), to antithesis (i.e., an observed anomaly or aspect of reality that is not known), to synthesis (i.e., a different, and better, understanding of reality that is gained through reconciling the unknown with the known). From Hegel's viewpoint, each synthesis offers transcendence to a higher, improved level of knowledge about reality.
Consider, for example, the thesis Idea, whose natural antithesis is Nature (i.e., mind and body). The grand synthesis of the two is Spirit, the self-awareness of the "absolute" itself. The Spirit, then, which can be observed through consciousness of thought, and the Objective, which can be observed as empirical events, can be synthesized to gain an ever improved knowledge of reality.
Hegel viewed the world as determinedly historical. He believed that history itself was the movement to greater self-consciousness of the Absolute. Because history inevitably follows the pattern of the dialectic, the present age must be the highest stage of development, with room for improvement. The task of the philosopher, indeed of all persons, is to pursue even greater understanding of the Absolute through synthesis of current knowledge and observations that provide new knowledge of the Absolute.
Hegel's assertion that one could eventually know the Absolute and that human progress was determined by history was criticized during his time and since. His advocating of the dialectic as a means of reconciling reason and empiricism, however, has been highly influential in western philosophy. It is said, for example, that Karl Marx "turned Hegel on his head" in his use of the dialectic to better understand the material rather than spiritual conditions of human existence.