There are both historical reasons and reasons grounded in the subject itself to devote to the topic of physicalism a special section on Moritz Schlick's philosophical doctrines.¹ The term physicalism was proposed by Otto Neurath in his work Empirical Sociology² for a set of theses originating from the writings and discussions of the circle round Schlick and was intended to demonstrate the fundamental attitude of that circle towards problems considered to be of philosophico-scientific importance. Physicalism thus became, for some members of the circle, the briefest characterization of their theoretical position and it soon entered the polemical vocabulary of exchanges between supporters and opponents of that position. It served, and still serves, as a profession of faith on the one side and as a stumbling block on the other. Clearly, then, it will be of interest to know how the founder reacted to his school's being given this name.