O universal construído: tipos naturais a partir de Locke

Abstract

The present dissertation explores the problem of universals from John Locke's conventionalism, which proposes an inflection in the debate by shifting the ontological focus to an epistemological approach, centered on his theory of abstract ideas. Locke, in contrast to the traditional natural kind essentialism (from Plato and Aristotle), introduces the distinction between real (inaccessible) and nominal (conventional) essences, the latter prevailing in the classification of species. His skepticism about the accessibility of real essences and adherence to the soritic problem inherent in the doctrine of the Great Chain of Being lead him to argue that the demarcation between species is arbitrary. The research will analyze the viability of Locke's moderate conventionalism in contemporary debate. The first chapter will present a historical overview of the problem of universals, from Antiquity to Locke, analyzing realist and nominalist theories, and detailing Locke's theory of abstract ideas and the objections of Hume and Leibniz. The second chapter will investigate the implications of Locke's proposal for the subsequent debate, addressing the reception of abstraction in the Kantian system, the problem of colors, and the influence of Kripke and Putnam's new theory of reference, as well as criticisms of these approaches. The third chapter will explore the realist/nominalist polarization in biological sciences, discussing the tension between essentialist and historical approaches, David Hull's species-as-individuals theory, Richard Boyd's Homeostatic Property Clusters (HPC), and John Dupré's promiscuous realism, in addition to addressing ontological vagueness and the notions of individuation and identity. The dissertation starts from the hypothesis that Locke's moderate conventionalism, reinterpreted in light of recent discussions, offers an adequate resource for understanding the problem of natural kinds and a promising path for metaphysics and epistemology. The analysis will demonstrate that very simple elements (such as elementary atoms and molecules) can be classified as natural kinds with fixed essences. However, in more complex beings, such as biological species, the theory of evolution and advances in biology demonstrate that natural kind essentialism is inadequate, making the arbitrariness in species delimitation inevitable and reinforcing the fundamental role of conventionalism.