In "Pseudorationalismus der Falsifikation", an article which appeared in Erkenntnis in 1935, Neurath turned the charge of "pseudorationalism" against Karl Popper's Logik der Forschung. This book, considered to be one of the major works of the philosophy of science of our time, had been published in the autumn of 1934 in the series Schriften zur wissenschaftlichen Weltauffassung edited by Schlick and Frank,¹ and had received sympathetic treatment from Carnap, who defended it in class="EmphasisTypeItalic ">Erkenntnis against the criticisms of Reichenbach.²