The whole of this book is an argument against the continuity thesis (exemplified by Lindberg, The Beginnings of Western Science (1992)), but I want in this note to present some general arguments and to offer some crucial concessions.
The argument that there were no sciences before Tycho saw his nova in 1572 is open to some obvious (but mostly mistaken) objections. Kuhn thought Ptolemaic astronomy was a mature science (Kuhn, Structure (1970), 68–9): it certainly had functioning paradigms and a capacity for progress. Although some of its central arguments – that all movements in the heavens are circular, that there is no change in the heavens, that the earth is at the centre of the universe, that there can be no vacuum – derived from philosophy (Kuhn, The Copernican Revolution (1957) calls these ‘blinders’ (86) and ‘entanglements’ (90)), they corresponded rather well with experience. And it made possible, not only Copernicanism, but also Tycho’s research programme. Astronomy, though, was a peculiar discipline because it accepted unquestioningly the Aristotelian distinction between the sublunary and supralunary worlds. That distinction only began to break down in 1572, and with it went the notion that there might be different principles governing different parts of the universe, that there could be different sciences for different places. 1572 thus really is a crucial moment of change.
There are strong arguments for thinking that Aristotelian biology was a science (Leroi, The Lagoon (2014)). But Aristotle established no tradition of biological enquiry. In the seventeenth century William Harvey saw himself as an Aristotelian biologist, but he recognized only one person between himself and Aristotle who had understood how to conduct biological research, and that was his own teacher (and Galileo’s friend), Girolamo Fabrizi d’Acquapendente (Lennox, ‘The Disappearance of Aristotle’s Biology’ (2001); Lennox, ‘William Harvey’ (forthcoming)). Similarly, there are strong arguments for thinking that Archimedes was a scientist (Russo, The Forgotten Revolution (2004)), but his science had little influence in the Middle Ages except in so far as it could be integrated into Aristotelianism; it is only late in the sixteenth century that the mathematicians begin to imagine an Archimedean science which might supplant Aristotle (Clagett, ‘The Impact of Archimedes on Medieval Science’ (1959); Laird, ‘Archimedes among the Humanists’ (1991)). Thus the Scientific Revolution recuperated the lost sciences of Aristotelian biology and Archimedean mathematics; but very quickly it moved away from its sources: Harvey had no followers who claimed, as he did, to be true Aristotelians, and Galileo had no followers who claimed, as he did, to be disciples of Archimedes.
As far as Kuhn was concerned, Aristotelian dynamics was itself a mature science (Kuhn, Structure (1970), 10; see also Kuhn, The Copernican Revolution (1957), 77–98; Kuhn, The Essential Tension (1977), 24–35, 253–65; Kuhn, The Road since Structure (2000), 15–20). Although he refused to recognize that optics was a science before Newton, because there were always competing schools (and so no ‘normal’ science), he presented Aristotelian dynamics as a successful paradigm which was supplanted in the late Middle Ages by impetus theory, which in its turn led to Galileo’s new physics (Kuhn, Structure (1970), 118–25). The test here is that ‘the successive transition from one paradigm to another via revolution is the usual developmental pattern of mature sciences’ (Kuhn, Structure (1970), 12). But the medieval theory of impetus produced no such transition. Aristotle continued to be the textbook, and although the theory of impetus was used to patch and mend problems within Aristotle’s theory, there were no separate treatises devoted to impetus theory (Sarnowsky, ‘Concepts of Impetus’ (2008)). Impetus theory was used to handle some anomalies, not to bring about a revolution; indeed, medieval natural philosophers were incapable of imagining a revolution that would supplant Aristotle. Because they were not conducting normal science, they never finally resolved the problems that puzzled them. There are two characteristic forms that natural philosophy takes in the Middle Ages: one is the commentary on Aristotle; the other is the collection of quaestiones, of problems to which there is no agreed solution. Over time new problems were added; old ones were never eliminated.
Of course one reason why Aristotelian natural philosophy survived virtually unchallenged through the Middle Ages was that outside three very restricted areas (the magnet, the rainbow, alchemy) experiments were not conducted, and where appeals to experience were made these never involved measurement. Thus in the vast bulk of Clagett, The Science of Mechanics in the Middle Ages (1959), the first proper experiments are those conducted by Galileo. Turn to the even vaster bulk of Grant (ed.), A Source Book in Medieval Science (1974), and we find, for example, a section entitled by its editor ‘Experiments Demonstrating that Nature Abhors a Vacuum’ (327–8), translated from Marsilius of Inghen (1340–1396). But these are experientiae or experiences: Marsilius has collected examples of phenomena which seem best explained by the claim that nature abhors a vacuum (one can suck water up through a straw, for instance). He has not conducted any experiments. When we turn to William Gilbert (On the Magnet, 1600), on the other hand, we find not only specially designed experiments, but also (something we do not find in his predecessors, such as Garzoni) experiments that require measurements.
A very powerful intellectual tradition has been dedicated to showing that medieval philosophy was a precondition for modern science (e.g. Grant, The Foundations of Modern Science (1996); Hannam, God’s Philosophers (2009)). This work builds on the pathbreaking studies of Pierre Duhem (1861–1916), Annalise Maier (1905–1971), and Marshall Clagett (1916–2005). It is no part of my argument to dispute the claim that we only have the sciences we have because Aristotle and the medieval philosophers opened up certain lines of enquiry; the first scientists inherited a set of problems from their predecessors, but their procedures for resolving those problems were new, and the intellectual tools they constructed to facilitate those procedures were drawn not from philosophy but from astronomy and the law. No medieval natural philosopher had a view of natural science as making progress, and no medieval natural philosopher was engaged in research, if we understand that to mean the gathering of relevant new information. Tycho, on the other hand, had a research programme which he conducted systematically over many years, and which he believed would resolve fundamental problems in contemporary astronomy; and with the idea of a research programme came, necessarily, the idea of progress.