PhD project

Decoding Descartes: The Making of Modernity

Doğukan Öztürkoğlu

In the doctoral project related to Decoding Descartes, Descartes’ contribution to the making of modernity will be studied in a manner to unearth his unremitting philosophical legacy. Descartes’ philosophy is often used as a trope for narrating the supposed animosity between rationalism and empiricism, and he is commonly portrayed as a philosopher who neglected sense-experience and focused solely on deductive reasoning. One of the principle reasons of this entrenched interpretation of Descartes can be found in the little attention that his correspondence with the savants of his time has received. Descartes, as was customary in early modern Europe, favoured correspondence with other natural philosophers for discussing his experiments and scientific theories. Besides this, some crucial works in which he expounded scientific theses remained unpublished during his lifetime. When his voluminous correspondence, along with his unpublished works, is taken into account, what emerges is a philosopher passionate about conducting experiments in order to prove the viability of his theories.

Rich in observations and dialogue on scientific developments, the correspondence is not only essential for comprehending Descartes’ scientific undertaking, but is also important for appreciating Descartes’ contribution to the modern worldview. By using experiments as a justificatory basis for scientific theories, Descartes’ scientific practice constitutes a radical break in the history of natural philosophy. In the Discourse on the Method, he remarkably claims that, regarding natural philosophy, suppositions (or hypotheses) may be proven by the effects that they explain (AT VI, p. 76). In this sense, any hypothesis about nature derives its power from its explanatory effectiveness. This particular view of natural philosophy’s aim is also the main reason why Descartes rejected the scholastic approach in physics. He confutes the scholastic theory of substantial forms by arguing its inadequacy for explaining the natural phenomena themselves; the forms not only fail to extend our knowledge about nature, they are also in need of explanation themselves (AT XI, pp. 25-26). Descartes claims that heat, cold, moistness, and dryness, which are the four main qualities of scholastic substance theory, along with all that exists in nature, can be explained without assuming anything in their matter but motion, size, shape, and the arrangement of their parts.

By advancing this mechanical understanding of nature, Descartes, along with some of his contemporaries, disenchanted the world by no loner accepting the idea of occult powers, such as substantial forms, being embedded in matter. He supplants the inherent principles that were taken to identify and animate natural phenomena with a physics that analyses matter through its quantifiable features. Descartes’ rejection of scholastic substance theory and his endeavour to explain natural processes without relying on a metaphysical scheme about the inner quality of things emancipated natural philosophy from the yoke of metaphysical disputes about real qualities. Accordingly, Descartes should not only be considered a forerunner of the scientific revolution on the basis of his own contributions to science, but also for laying the groundwork for modern science to develop independently of metaphysics.

Besides his significant contribution to the development of modern science, Descartes established a pivotal shift in philosophy proper that has shaped the modern worldview and philosophical discourse ever since. This shift results from a new understanding of metaphysics that outlines the limits of human knowledge and conditions of its reliability. Devising the philosophical framework within which science is possible and meaningful seems to be the goal of Descartes’ metaphysics. In this respect, even the mind-body dualism due to which Descartes is unduly depicted as a bizarre metaphysical speculator, functions as a safeguard against re-enchanting the world with supernatural entities such as substantial forms. A radical division between the mind and the body, coupled with the impossibility of interaction and causation between the two realms, ensures maintaining theories about natural processes and phenomena solely on physical grounds, independent from any metaphysical input. This equally clears the way for science to develop. Strikingly, Descartes, in the Treatise on Man, contends that even human physiology and behaviour could be understood without presupposing a soul; he announces that a fully mechanical account of how our body functions is explicated in this work (AT III, 667).

Reconstructing Descartes’ philosophy by bearing in mind his scientific ambitions paves the way for a better contextualisation of his metaphysics. It also enables us to unearth Descartes’ unremitting legacy. One place where this legacy has been positively effective is in transcendentalism. Placing the subject and an examination of its cognitive faculties at the heart of his philosophy, Descartes pioneered a new approach that was adopted even by his detractors. He inquired about our cognitive capacities and the way in which we understand the world in order to determine the scope and reliability of our knowledge. By investigating how we perceive the world, Descartes started a new train of thought that freed itself from speculating on how things are ‘in themselves’. From Malebranche to Kant, placing the knower in the centre of inquiry in order to determine its limits remained an crucial feature of modern philosophy. In this PhD project, it will be argued that, as a result of Descartes’ pursuit of knowledge, metaphysics takes a whole new meaning; as it is freed from an ambition to render natural processes intelligible by means of supernatural forces, it becomes a comprehensive study of the possibility of science and reliability of sense experience.