 So now the two-dimensionality of perceptual space, for instance, is no longer obtainable from phenomenological discernment, but becomes as much a logical construction as everything else ( Aufbau: §§89, 117, 124). And in a talk Carnap gave about the Aufbau project in Vienna in January 1925, we find a new guiding principle: “Overcoming subjectivity” (Carnap 1925a, 1925b, as quoted in Carus 2007a: 168; 2016).