 Early in his intellectual life, at the turn of the twentieth century, Neurath was acquainted with at least four recent images and projects of unification of the sciences: (1) The scholastic (Llull) and rationalist (Leibniz) tradition of an ideal universal language and calculus of reasoning; (2) the Neo-Kantians’distinction between the Naturwissenschaften and the Geisteswissenschaften; (3) Wundt’s comprehensive logical viewpoints associated with different sciences, or perspectival monism; and (4) the Monist movement more generally, with figures such as Ernst Haeckel and Wilhelm Ostwald that included the project of energetics, with Mach’s related bio-economic, neutral monism of elementary sensations. Subsequently, throughout the 1910s, Neurath engaged four connected debates: (1) The debate over the Neo-Kantian divide between natural and human, or cultural, sciences; (2) the debate over the distinctive role of value judgment in the social sciences; (3) the debate over the scope and validity of concepts and laws in economics; and (4) the debate over the possibility of history as a positive science.