The history of modern metaphysics is essentially marked by its splitting up into a metaphysica generalis and a metaphysica specialis, a well-known distinction especially within Christian Wolff’s systematic conception of metaphysics. This study investigates the actual origins of this significant development, which can be already found at the beginning of the 14th century. On the basis of a fundamentally revised doctrine of transcendentals the Franciscan theologian Francis of Marchia (~1290-1344) introduces for the first time a dissociation of the primum cognitum of the human intellect from the subject of metaphysics, according to which metaphysics is no longer one science in the sense of a scientia transcendens, as most of his predecessors claimed in the 13th century, but rather twofold: ontology and theology.

Gary Hatfield examines theories of spatial perception from the seventeenth to the nineteenth century and provides a detailed analysis of the works of Kant and Helmholtz, who adopted opposing stances on whether central questions about spatial perception were amenable to natural-scientific treatment. At stake were the proper understanding of the relationships among sensation, perception, and experience, and the proper methodological framework for investigating the mental activities of judgment, understanding, and reason issues which remain at the core of philosophical psychology and cognitive science. Hatfield presents these important issues as living philosophies of science that shape and are shaped by actual research programs, creating a complex and fascinating picture of the entire nineteenth-century battle between nativism and empiricism. His examination of Helmholtz's work in physiological optics and epistemology is a tour de force. Gary Hatfield is Associate Professor of Philosophy at the University of Pennsylvania.