Many historians of the calculus deny significant continuity between infinitesimal calculus of the seventeenth century and twentieth century developments such as Robinson’s theory. Robinson’s hyperreals, while providing a consistent theory of infinitesimals, require the resources of modern logic; thus many commentators are comfortable denying a historical continuity. A notable exception is Robinson himself, whose identification with the Leibnizian tradition inspired Lakatos, Laugwitz, and others to consider the history of the infinitesimal in a more favorable light. Inspite of his Leibnizian sympathies, (...) Robinson regards Berkeley’s criticisms of the infinitesimal calculus as aptly demonstrating the inconsistency of reasoning with historical infinitesimal magnitudes. We argue that Robinson, among others, overestimates the force of Berkeley’s criticisms, by underestimating the mathematical and philosophical resources available to Leibniz. Leibniz’s infinitesimals are fictions, not logical fictions, as Ishiguro proposed, but rather pure fictions, like imaginaries, which are not eliminable by some syncategorematic paraphrase. We argue that Leibniz’s defense of infinitesimals is more firmly grounded than Berkeley’s criticism thereof. We show, moreover, that Leibniz’s system for differential calculus was free of logical fallacies. Our argument strengthens the conception of modern infinitesimals as a development of Leibniz’s strategy of relating inassignable to assignable quantities by means of his transcendental law of homogeneity. (shrink)

I first met Ivor Grattan-Guinness and his wife Enid in the late summer of 1970. I was in England following an intensive course in German at the Goethe Institute in Prien am Chiemsee, and had arrang...

: Half a century of political Marxism and Soviet social science deflected Marxist thought from its canonical sources. Communism and Marxism were so intertwined by events of the twentieth century that it is difficult to see what remains of the latter after the demise of the former. Specifically, three foundational principles--"being determines consciousness," the Asiatic Mode of Production, and "the ideas of the ruling class are the ruling ideas"--have been corrupted by heartfelt ideological commitments. A review of those principles against (...) the background of Marxist writing on the history of science stakes out research frontiers that remain to be reconnoitered. (shrink)