The psychological, cosmological, and theological Ideas are nothing but pure concepts of reason. They cannot be experienced. All questions about them must be answerable because they are only principles that reason has originated from itself in order to achieve complete and unified understanding of experience. The Idea of a whole of knowledge according to principles gives knowledge a systematic unity. The unity of reason's transcendental Ideas has nothing to do with the object of knowledge. The Ideas are merely for regulative use. If we try to use these Ideas beyond experience, a confusing dialectic results.