How Theology, Imagination, and the Spirit of Inquiry Shaped Natural Philosophy in the Late Middle Ages

Abstract

Historians of science have long debated historiographical issues and have even come to regard some of them as rather passe. The issues I shall consider will be applied to late Middle Ages and, where necessary, extended to early modern period, or, as I shall refer to it, Scientific Revolution. In broad range of medieval science and philosophy, I shall focus almost exclusively on philosophy, because, as we shall see, philosophers posed questions that probed all aspects of world: nature, supernatural, and an imaginary world of hypothetical and possible.1 It included bits and pieces of virtually all of contemporary sciences, as well as thoughts and ideas that would be appropriate to that only came into being in modern era. It was not until of astronomy, optics, and mechanics - exact sciences, known as middle sciences to Aristotle and his followers in late Middle Ages - became fully integrated with philosophy in seventeenth century that early modern science emerged. Although process of integration began in Middle Ages, it accelerated rapidly in seventeenth century. The importance of union between exact and philosophy was truly significant. Other societies that at one time had well-developed mathematics and astronomy, but failed to generate, and maintain, a well-developed philosophy, eventually saw their mathematical fade away. A prime example is civilization of Islam.2 In what follows, I shall focus on two basic issues that are most relevant to philosophy and should be of great interest to historians of science. I shall first consider influence of theology and religion on philosophy and exact sciences; and then investigate a topic that, although connected to first theme, emphasizes role of reason, imagination, and counterfactuals, which taken together produced a spirit of inquiry that encouraged investigation of nature and development of science. Because philosophy is focus of my essay, I shall now present a brief summary of highlights of medieval philosophy.NATURAL PHILOSOPHY IN THE LATE MIDDLE AGESDuring Middle Ages, philosophy was solidly based upon Aristotle's natural books [libri naturales], which included Physics, On heavens, On generation and corruption, Meteorology, On soul, and The short physical treatises (Parva naturalia). Since these works treated different aspects of physical cosmos, philosophy ranged over all aspects of physical world that involved change. For most scholastic philosophers, subject matter of philosophy was 'mobile being [ens mobile]', a term that Thomas Aquinas used. 'Mobile being' rather than 'mobile body' was used because it embraced motion of both material and immaterial substances. Natural philosophy was concerned with change as manifested by things in some kind of motion. As an anonymous fourteenth-century author expressed it, the whole of movable being is proper subject of philosophy.3 Most of subjects discussed were drawn from broad range of Aristotle's philosophy.Medieval philosophy was presented in three quite different literary formats. The first, commonly in use through most of thirteenth century, was commentary. In this format, whichever of Aristotle's books was subject of commentary, author would present a few lines of Aristotle's text and then explain them while also commenting on them. He would then do same for text immediately following, and move through entire treatise in same fashion, paragraph after paragraph until commentary was completed. The second, and most popular, way of proceeding was by way of a series of questions, each of which usually began with word 'whether [utrum] In Physics, we could readily meet a question such as Whether existence of a vacuum is possible; in On heavens, we might confront question Whether whole earth is habitable; from Meteorology, a question on visual rays would be fairly common, such as Whether every visual ray is refracted in meeting a denser or rarer medium; and in questions on On generation and corruption, it would be frequently asked Whether elements remain [or persist] formally in a compound [or mixed] body. …