With Kant, we called synthetic those judgments that attribute to an object something not contained in the concept of that object. The relation between subject and predicate in a synthetic judgment is not given by a definition; it is established by knowledge. The question of the validity of such judgments can be resolved only on the basis of insight into the nature of the cognitive act. We must accordingly turn back to the results of the first part of our inquiry. Not only do we find there the elements required to solve our problem; we also find the problem itself, which had already made its appearance on several occasions. At the time we were obliged to postpone an answer, even though the question troubled us very much. We were disturbed because there seemed to be no road that could lead us to indubitable, exact knowledge of reality. Now it is time to examine systematically the various possible paths. Perhaps there is some way to the earnestly sought goal of absolutely valid truths about reality, but the approach may not have been visible from the course taken thus far by our inquiry.