The second chapter studies the efforts of the Christian Ḥunayn ibn Isḥāq, whose workshop in ʿAbbāsid Baghdad translated the Galenic sources considered in this book, to enhance the respectability of the specialism of ophthalmology in his Ten Treatises on the Eye. I show that, even more so than medicine, ophthalmology was at a disadvantage in its pursuit for epistemic authority because Galen himself had attacked the sub-field as an exemplar of the worrying tendency among doctors in Rome and other cities towards specialization, which threatened the unity of the discipline and the health of patients. Concerned with his own intellectual status at court, Ḥunayn, I argue, subversively uses Galen's explanation of the Timaeus' description of the eyes' service to the rational soul to give ophthalmologists a stake in medico-philosophical controversies relating to sensation. I also expose how Ḥunayn modifies Galen’s interpretation of Plato’s teleological ocular anatomy and visual theory in order to privilege the eye over all other organs as a window to cosmic knowledge.

Chapter 5 is a direct continuation of the stylistic features discussed in Chapter 4. Rather than focusing on intra-textual aspects, though, this chapter looks at the extra-textual factors medium, hypokrisis (delivery) and audience, all of which further influence lexis on its third level. The chapter finishes with an examination of the purpose and function of lexis on its third level.

Galen attempts to define the Timaeus as a medical resource to justify medicine’s right to comment on issues regarding the soul and the nature of life, to which philosophers had long laid claim. I call attention to Galen’s commentary On the Medical Statements in Plato’s Timaeus and the Arabo-Latin prologue to the Synopsis of Plato’s Timaeus to illustrate how his assertions that the dialogue contains ‘medical’ information allow him to draw more expansive boundaries for medicine. My analyses of On the Doctrines of Hippocrates and Plato and The Faculties of the Soul Follow the Mixtures of the Body reveal that Galen advances more monopolistic claims on the soul for medicine by appealing to his anatomical expertise and the dialogue's link between bodily and psychic disease to show the pertinence of his medical expertise to psychological controversies and ethics. I conclude with a discussion of Galen's interpretation of the Timaeus' account of vegetative sensation, which posits a homology between plants and humans that he exploits to extend medicine's boundaries beyond the world of the body.

Chapter five concentrates on the Rabbi Moses Maimonides' reformist project to rid Galenism of its Timaean elements. As I establish, while Maimonides' affiliation with Aristotelianism put him in conflict with Galen, the Platonic lines in Galen's thought also generated problems for his own conception of Jewish belief. I show that Maimonides rejected Galen's reading of the Timaeus' cosmogony as heterodox in the Guide for the Perplexed and Medical Aphorisms because of its denial of creation ex nihilo and the omnipotence of God. Therefore, Maimonides had theological reasons for wishing to curtail Galen's philosophical reach. Giving special attention to the Medical Aphorisms, I uncover the various polemical tactics that Maimonides employs, which include giving more limited meanings to Galen's philosophically loaded terminology and mobilizing his own anatomical experience to dispute Galen's brain-centred theory of sensation, to dephilosophize Galenism and recentre it on the body.

Chapter 2 begins with an outline of the four passages in which Aristotle introduces the three pillars of lexis and then moves on to two sections in which the first, i.e. ἅπασα λέξις (the entirety of lexis), is discussed. This first level of lexis includes the linguistic elements treated under the notion of lexis and Aristotle’s theory of language. These not only present Aristotle’s thoughts on language as an abstract system, but they also form the most fundamental level upon which the remainder of Aristotle’s thoughts on the concept of lexis are based.

Thomas Reid's philosophy of common sense exercised a significant influence on Western thought and continues to be relevant today. It appeared on the world stage as a scientific philosophy amenable to Christian beliefs, the rise of a modern public sphere and democratic politics. Exercising its most profound impact in postrevolutionary France and America, it promised to combine progress and stability, establishing links between common-sense experience and philosophical and scientific thought in an era of rapid sociopolitical, religious, and scientific change. It had a significant impact on the development of higher education in both countries and was an important undercurrent in the broad expanse of nineteenth-century intellectual culture, a current which fed and mingled with other streams of thought.

Although an identifiable school of “common-sense philosophy” began to wane around the middle of the nineteenth century, Reid's philosophy proved to be a multivalent and fertile influence on subsequent philosophical developments in Britain, France, and America. Reid's impact in Germanspeaking lands was slight but worth considering. And today his thinking remains pertinent not only to philosophers but also to psychologists, cognitive scientists, and philosophers of science. In what follows, I first provide an analytical overview of Reid's historical influence and impact in Britain, France, Germany, and America, before concluding with some observations on the relevance of his thought to the findings of contemporary research into the nature and structure of the human mind and to the ongoing scholarly discussion about the relationship between common sense and scientific inquiry.

Reid's thought gained an immediate following upon publication of his Inquiry in 1764. James Oswald (1703–1793) was a Scottish minister who published An Appeal to Common Sense in Behalf of Religion in two volumes (1766/ 1772). Although he cited Reid sparingly, Oswald seized upon Reid's ideas to defend the faith from “the assertions of sceptics and infidels,”1 opposing the common-sense principles that ordinary people take for granted to the labored and drawn-out reasonings of the learned, the latter threatening to confound the instinctive moral and religious impulses possessed by all human beings.

The French Jesuit scholar Claude Buffier (1661–1737) was the first modern thinker to develop a fully fledged philosophical doctrine of common sense (sens comun). In his philosophical writings, Buffier sought to shore up connections between the human mind and the external world that had been left tenuous by Descartes and Locke. The inherent skepticism and idealism of modern philosophy did not square with the rough and ready perceptions of the average person, and Buffier sought to ground higher thought in common-sense experience.

Like most common-sense philosophers who followed after him, Buffier was an educator, and consequently he was very responsive to the growth in literacy and the rise of a modern public sphere of enlightened discourse that was in principle open to everyone. As a young man he taught courses in the humanities, and after joining the Jesuit order in 1695 he became a full-time man of letters who published popular works of history, philosophy, religion, geography, ethics, grammar, and logic, culminating in his 1732 Cours de sciences, a complete course of studies for youth. He was a sociable figure who moved in aristocratic circles and attended fashionable salons, yet he remained at heart a popularizer who aimed to make higher learning accessible to the average person. Buffier spearheaded the trend in Jesuit education toward studying history and geography as independent subjects, and his widely adopted textbook on French grammar helped to focus more attention on the vernacular. Buffier, who frequented the salon of the feminist Marquise de Lambert, was also a supporter of female education, arguing that women are as intelligent as men. He has thus been seen as “a radical and reforming element within the structure of Jesuit education.”

Buffier was a scriptor (scholar/ writer) at the intellectually vibrant Collége Louis-le-Grand in Paris from 1701 until his death in 1737, and he was a founding editor of the Mémoires de Trévoux, a cosmopolitan journal that featured articles and reviews on a variety of learned topics, written mainly by Jesuits but also by other members of the European Republic of Letters, including Leibniz.

The thought of Thomas Reid (1710–1796) presents a fitting climax and culmination of the story we have been following about the relationship between common sense and science dating back to the ancient Greeks. As we have seen, by the turn of the eighteenth century the New Science had challenged the intellectual primacy of common-sense experience in favor of recondite, expert, and even counterintuitive knowledge increasingly mediated by specialized instruments. Meanwhile modern philosophical thinking that emerged in tandem with the New Science, including skeptical and materialist currents of thought, had problematized the perceptions of everyday sense experience and accepted understandings of the self, morality, religion, and society. Everything was “up for grabs,” intellectually, and thinkers from across the intellectual spectrum and throughout Europe felt compelled to revisit the grounds of our most basic beliefs and forms of knowledge.

In the case of Reid's contemporary David Hume (1711–1776), reexamination of the fundamental bases of human knowledge led to skeptical scrutiny of, among other things, our perception of causal relations in nature, a fundamental precondition of scientific endeavor. In this chapter I argue that in responding to this “problem of induction” as advanced by Hume, Reid completed the long-term philosophical process, outlined in previous chapters, of reconnecting everyday understanding and experience with the findings and methods of modern natural science. An educator and mathematician selfconsciously working within the framework of the New Science, Reid articulated a philosophical foundation for natural knowledge anchored in the human constitution and in processes of adjudication in an emerging modern public sphere of enlightened discourse. Reid thereby completed the ongoing intellectual transformation of one of the bases of Aristotelian science—common experience—into a philosophically and socially justified notion of “common sense.” This fact, along with the fact that his perspective—and that of the common-sense/ moral sense philosophical tradition generally—was supportive of orthodox Christian theology and moral precepts, helps to explain why Reid's thought was so influential in nineteenth-century Europe and America (discussed at length in the Epilogue).

Previous chapters have shown how a variety of European thinkers—including Herbert of Cherbury, René Descartes, Henry Lee, G. W. Leibniz, and Henry More, among others—were beginning to explore and develop the idea that human beings intuitively perceive certain notions, ideas, truths, or principles that condition our experience and make moral, scientific, and religious knowledge possible. We have seen how Claude Buffier was developing a philosophy of sens comun in eighteenth-century France and how the seeds of a philosophy of common sense were being planted in the British Isles by moral philosophers like Francis Hutcheson in Ireland and Scotland, and the Third Earl of Shaftesbury and Bishop Butler in England, where the figure of “common sense” as a term of popular culture was emerging in its own right.

Now we turn our attention to Enlightenment Scotland, where a fullyfledged philosophy of common sense, with strong links to modern science and the scientific method, began to emerge: first in the works of George Turnbull and Henry Home, Lord Kames, before coming to full fruition in the work of Thomas Reid. Although previous European thinkers had been making similar arguments and observations, it was in Scotland that a coherent and developed “school” of common-sense philosophy grew and matured, extending deep into the nineteenth century and far beyond the shores of Scotland.

Hutcheson, Turnbull, Kames, and Reid were a subset of thinkers within the larger Scottish Enlightenment, which has come to assume a place in modern intellectual history that rivals the French Enlightenment. According to Donald Withrington, “The really distinctive mark of the Enlightenment in Scotland is that its ideas and ideals were very widely diffused, in all areas and among a very wide span of social groups, in what was for the time a remarkably well-educated and highly-literate population.” Alexander Broadie argues that the Scottish Enlightenment had roots stretching back to the fifteenth century and notes that its proponents were highly literate, sociable, and engaged in various intellectual clubs and societies, and as such “lived in each other's intellectual pockets.”

Modern science was founded in part on a distrust of ordinary sense experience and “appearances” in favor of corpuscular, idealized, and mathematical truths. The world of everyday experience needed to be reexamined, tested, transcended, put on the rack, and reduced (at least in theory) to invisible forces and minute particles in order to be understood. The writings of early-modern philosophers like Descartes, Hobbes, Locke, and Hume, who were deeply influenced by the discoveries and methodologies of modern science, exhibited this perspective, and the long-term effect was to place into doubt much that seemed to be self-evidently true and spontaneously known.

The first major event in this story was the advent of Copernicanism. There was no more significant and far-reaching challenge to the common-sense underpinnings of scientific thought and practice than the idea that the earth moves in a double motion around the sun—an idea which labored under the burden of contradicting Scripture as well. The challenge to Scripture, and with it the medieval Christian worldview and power structure, often receives the most attention in discussions of the travails of Copernicanism. But as both Calvin and Galileo recognized, if there was a discrepancy between science and Scripture on astronomical questions, that was because the Scriptural writers had been addressing the common folk, on their own terms, about salvation and were not trying to teach them astronomy. Thus although religious concerns and controversies were clearly central to the way in which Copernicanism and the new physics that went with it were received, there can be little doubt that Copernicanism exemplified the challenges posed by modern science to common-sense experience, even as sense experience itself began to assume an authority that it had not held since Aristotle.

Copernicus himself realized the absurdity of his proposal, noting that it was “in opposition to the general opinion of mathematicians and almost in opposition to common sense [communem sensum] [that] I should dare to imagine some movement of the earth.” Here, Copernicus employs the term “common sense” to signify basic sense perceptions shared by everyone, as opposed to more abstruse mathematical knowledge. Copernicus's early Polish defender Barholomew Keckermann (d. 1609) argued that “ ‘Everything indicates that the movement of the Earth as assumed by the greatly famed Copernicus must not be regarded as a realistic term but as an astronomical working term.’ “