Peirce did not achieve a final systematization of his work. Beyond the difficulties in explaining so many philosophical tools that he introduced—suffice it to mention semiotic, abductive logic, a heuristic based on continuity, scholastic realism—, there is a theoretical reason for this incompletion. All those new philosophical tools indicated a conception of synthesis very different from the one he received from Kant. Peirce did not realize the profound direction of his enquiry so that he did not directly question neither Kant’s legacy on this issue nor the idea of necessity that presides over it. Starting from Peirce’s conception of continuity and change, this paper will give a new definition of synthetic and analytic judgments and reasoning, completing the picture with a third “vague” judgment and reasonin g. In this new definition a synthetic judgment is a judgment that recognizes identity through changes. An analytical judgment is a judgment that loses identity through changes. A vague judgment is a judgment that it is blind to identity through changes. How do we perform synthetic reasoning? Following Peirce’s semiotic study of elements of Gamma Graphs as the sheet of assertion and the line of identity, the paper will first individuate the semiotic characteristics necessary for the recognition of identity. These characteristics lead us to discover “complete gesture” as the tool that we use in our every-day reasoning in order to acquire new knowledge synthetically. “Complete gestures” are actions through which we carry and recognize significant meanings. This new paradigm should provide an improved account of common-sense knowledge as well as of particular creative and hypothetic stages of conception in both scientific and humanistic thought.