parenthesis sentence

What is meaning of the bold clause? Is it a part of what Peirce labeled as a priori method? Is it supposed to say that the consensus is emerged through the a priori method? (Because the consensus can't be a method)Is 'developing' an adjective? Does it mean growing or improving? Can I eliminate it in translation? The American pragmatist philosopher Charles Peirce pointed out another difficulty with the use of reason and logic—it can be used to reach opposing conclusions, easily observed in political discussions. Peirce labeled the use of reason...Read more