 The core idea from which Brentano starts is very simple: traditional logic takes the A-form and the I-form to express positive judgements, and the E-form and the O-form to express negative ones. According to Brentano, that is a confusion. All universal propositions (both A and E) express negative judgements and therefore lack existential import, whereas all particular propositions (both I and O) express positive judgements with existential import. The reduction thesis fits in nicely with this idea, or so it seems. It helps us to correctly interpret the principles of traditional logic and to see which of them one should retain. In turn, the simplification of the square of opposition lends support to the reduction thesis. Everything seems to fit  nicely.[23]