This paper tries to answer the question of what is the place -if there is any- that the common sense of jurists occupies in the Alexyan theory of formal principles, particularly, regarding the presumption of constitutionality of the law. The answer is that (i) Alexy's theory captures the core aspects of that common sense, indeed, (ii) it contributes to refining some aspects of it, however, (iii) all of the above is obscured if the weight formula is included in the analysis, interpreting it as the exact reflection of the Alexyan theory.