Van Heijenoort's main contribution to history and philosophy of modern logic was his distinction between two basic views of logic, first, the absolutist, or universalist, view of the founding fathers, Frege, Peano, and Russell, which dominated the first, classical period of history of modern logic, and, second, the relativist, or model-theoretic, view, inherited from Boole, Schröder, and Löwenheim, which has dominated the second, contemporary period of that history. In my paper, I present the man Jean van Heijenoort (Sect. 1); then (...) I describe his way of arguing for the second view (Sect. 2); and finally I come down in favor of the first view (Sect. 3). There, I specify the version of universalism for which I am prepared to argue (Sect. 3, introduction). Choosing ZFC to play the part of universal, logical (in a nowadays forgotten sense) system, I show, through an example, how the usual model theory can be naturally given its proper place, from the universalist point of view, in the logical framework of ZFC; I outline another, not rival but complementary, semantics for admissible extensions of ZFC in the very same logical framework; I propose a way to get universalism out of the predicaments in which universalists themselves believed it to be (Sect. 3.1). Thus, if universalists of the classical period did not, in fact, construct these semantics, it was not that their universalism forbade them, in principle, to do so. The historical defeat of universalism was not technical in character. Neither was it philosophical. Indeed, it was hardly more than the victory of technicism over the very possibility of a philosophical dispute (Sect. 3.2). (shrink)

What Frege’s paradox on concept and object (FP) consists in and the manner in which Frege coped with it (the ladder strategy) are briefly reviewed (§ 1). An idea for solving FP inspired by Husserl’s semantics is presented; it results in failure, for it leads to a version of Russell’s paradox, the usual solution of which implies something like a resurgence of FP (§ 2). A generalized version of Frege’s paradox (GFP) and an idea for solving it inspired by Davidson’s (...) semantics are presented; three theorems about recursive definability of truth are put forward and used to determine whether this idea can be successfully applied to certain putative forms of the Language of Science (§ 3). Proofs of these three theorems, in particular of the third, which answers a question that does not seem to have drawn logicians’ attention, are then given (§ 4). Finally, it turns out that there is a tension between the proposed solution of GFP and the idea of Language of Science assumed so far in this paper, and a way of solving it is proposed (§ 5). (shrink)

The standard version of the story of Russell's theory of types gives legitimately precedence to the vicious circle principle, but it fails to appreciate the significance of the doctrine of incomplete symbols and of the ultimate universalist perspective of Russell's logic. It is what the Author tries to do. This enables him to resolve the apparent contradiction which exists in "Principles" between the ontological commitment of the theory itself with respect to individuals, propositions, and functions, and the inventory of the (...) world, according to which there are only individuals and elementary facts. (shrink)