 Many of these issues were openly discussed at the Paris congress in 1935. Already in 1932 Carnap had sought to sharpen his previous criterion by stipulating that those statements were meaningful that were syntactically well-formed and whose non-logical terms were reducible to terms occurring in the basic observational evidence statements of science. While Carnap’s focus on the reduction of descriptive terms allows for the conclusive verification of some statements, it must be noted that his criterion also allowed universally quantified statements to be meaningful in general, provided they were syntactically and terminologically correct (1932a, §2). It was not until one of his Paris addresses, however, that Carnap officially declared the criterion of cognitive significance to be mere confirmability. Carnap’s new criterion required neither verification nor falsification but only partial testability so as now to include not only universal statements but also the disposition statements of science (see Carnap 1936–37; the English translation of the original Paris address (1936a [1949]) combines it with extraneous material). These disposition terms were thought to be linked to observation statements by a variety of reduction postulates or longer reduction chains, all of which provided only partial definitions (despite their name they provided no eliminative reductions). Though plausible initially, the device of introducing non-observational terms in this way gave rise to a number of difficulties which impugned the supposedly clear distinctions between logical and empirical matters and analytic and synthetic statements (Hempel 1951, 1963). Independently, Carnap himself (1939) soon gave up the hope that all theoretical terms of science could be related to an observational base by such reduction chains. This admission raised a serious problem for the formulation of a criterion of cognitive significance: how was one to rule out unwanted metaphysical claims while admitting as significant highly abstract scientific claims?