Abstract

Rudolph Carnap’s Aufbau was one of the more ambitious philosophical programs of the twentieth century. His proposal was to begin with elementarerlebnisse —cross sections of one total stream of experience temporally limited by the least perceivable segment of time—and an undefined primitive relation, recollection of similarity, holding between the elementary experiences. Without any further non-logical terms, the goal was to utilize a logic, such as that of Principia Mathematica, and actually to construct logically, or to define formally, all the kinds of entities, phenomenal, physical, psychological and cultural, which we usually take to make up our world. Unfortunately, the program is not completed. Only what Carnap refers to as the lower levels is actually formally constructed—that is, what might be called the phenomenal level. The remainder of the constructional program is only suggested in outline.