The sheer quantitativeness of modern empirical science is what makes our civilization possible, without which it would be inconceivable. Things were not always so. The ancients, while perfectly capable of logically precise reasoning, weren’t very quantitative apart from their astronomy because they lacked a mentality for which measurement and quantification are key – they lived under the sway of what the American historian Alfred W. Crosby calls the ‘venerable model’ in the work presently under view, The Measure of Reality: Quantification and Western Society, 1250-1600 (Cambridge University Press, 1997). Mankind dwelt in a comfortable universe, as it were, whose spatial and chronological bounds, though capacious enough, were not astronomically beyond the ability of common sense to accommodate, the arts and sciences comprehended their subject matter in mostly qualitative terms and numbers, in so far as they registered themselves, fitted into a pattern of filtering one’s experience of the world through a symbolic lens, as forcefully suggested by the tendency to a typological exegesis of scripture. The Middle Ages in western Europe, however, mark the inception of a major transition, when one moved at an accelerating pace to a ‘new model’ founded upon a coldly quantitative approach to reality. What were its stages and enabling factors?
It is always best to circle around a large question such as this while wielding an acquaintance with a broad array of actual historical phenomena that can be brought to bear upon it. This aspect of the Fragestellung is where Crosby’s work proves most valuable, for in a few short but incisive chapters he reviews its status with respect to the fields of technology, music, painting and finance. Crosby pays close attention to the interaction between theory and practice. New methods in the arts and sciences were in the air at the time: Arabic numerals, algebraic notation, clocks, double-entry bookkeeping, polyphonic music, perspective in painting. But Crosby also wants to tell the story of the societal effects of an age of exploration, in which new worlds were opened to conquest and colonization, book printing took off and facilitated the Reformation, the rise of capitalism underwrote sustained economic growth, and ultimately (past Crosby’s time frame) a technically sophisticated applied science issued in the agricultural, medical and communications revolutions that have profoundly changed the face of the modern world.
Let us quote at length a fine example of how Crosby graphically illustrates his point about the significance of the quantitative turn, which this reviewer finds particularly striking (not ever having been an entrepreneur):
Consider, for instance, one short chapter in the career of Francesco di Marco Datini, the merchant of Prato who liked to begin his ledgers with ‘In the name of God and of profit’. On 15 November 1394 he transmitted an order for wool to a branch of his company in Mallorca in the Balearic Isles. In May of the following year his sheep were shorn. Storms ensued, and so it was not until midsummer that his agent dispatched twenty-nine sacks of wool to Datini, via Peniscola and Barcelona in Catalonia, and thence to Porto Pisa on the coast of Italy. From there the wool traveled to Pisa by boat. There the wool was divided into thirty-nine bales, of which twenty-one went to a customer in Florence and eighteen to Datini’s warehouse in Prato. The eighteen arrived on 14 January 1396. In the next half year his Mallorcan wool was beaten, picked, greased, washed, combed, carded, spun, then woven, dried, teaseled and shorn, dyed blue, napped and shorn again, and pressed and folded. These tasks were done by different groups of workers, the spinning, for instance, by ninety-six women in their homes. At the end of July 1396, two and a half years after Datini ordered his Mallorcan wool, it was six cloths of about thirty-six yards each and ready for sale. The cloths were dispatched via mule over the Apennines to Venice for shipping and sale back to Mallorca. The market there was dull, so they were sent on to Valencia and Barbary. Some sold there, and some were returned to Mallorca for final disposal in 1398, three and a half years after Francesco had ordered the wool. – We may wonder at his patience, but – think a moment – how more wondrous was his ability to keep track of his business affairs, of which this matter of the Mallorcan wool was but one small part. How did this man even know whether he was a success or bankrupt? Merchants like Datini were driven to invent bookkeeping just as physicists were later driven to take up calculus. It was their only hope of knowing what was going on. [pp. 201-202]
Double-entry bookkeeping was and is a means of soaking up and holding in suspension and then arranging and making sense out of masses of data that previously had been spilled and lost. It played an important role in enabling Renaissance Europeans and their successors in commerce, industry and government to launch and maintain control over their corporations and bureaucracies. Today computers compute faster than friar Pacioli would ever have dreamed possible, but they do so within the same framework (accounts payable, accounts receivable, and all) as he did. [p. 220]
As Pacioli wrote, bourgeois Italian students, attending not cathedral schools or universities, but abacco schools (you might call them trade schools for merchants and their aides), were honing their mathematical skills on such problems as this: Three men, Tomasso, Domenego and Nicolo, entered into partnership. Tomasso put in 760 ducats the first day of January, 1472, and on the first day of April took out 200 ducats. Domenego put in 616 ducats on the first day of February, 1472, and on the first day of June took out 96 ducats. Nicolo put in 892 ducats on the first day of February, 1472, and on the first day of March took out 252 ducats. And on the first day of January, 1475, they found they had gained 3168 ducats, 13 grossi and ½. Required is the share of each, so that no one shall be cheated. [pp. 221-222]
A rather non-trivial task, even for one like the present reviewer accustomed to complicated calculations in physics! If one has ever glanced at today’s examination for chartered financial analysts, by the way, its problems are no less challenging, if not more so (discounting cash flows for risk-adjusted interest rates and so forth).
If one reflects a bit on the quoted passages, he may gain an impression of the sheer economic efficacy thereby liberated for one who possesses the sagacity to orchestrate his business affairs and to keep tabs on his momentary position by means of assiduous accounting. No wonder economic growth took off during the period of early capitalism in question!
A brief assessment of Crosby the historian’s performance here: solid, not overly technical or heavy on philosophy, well illustrated (literally and figuratively), succinct and therefore provocative. Any reasonably educated layman will be confronted with much food for thought, as he ponders the possible connections among the historical trends here discussed and relates them with what can be perceived unfolding all around us in our era. For us, the topic of greatest interest would be to interrogate what implications medieval civilization’s turn to the quantitative might have for the kinds of knowledge over which we dispose today – what have we gained, or lost, and where will it all lead? A subsidiary theme that seems to have figured in Crosby’s motivation for writing this piece in the first place is this: competence in quantitative matters in fact unleashes hitherto unsuspected power, both over nature and over other men, and contributes a key enabling factor to European civilization’s rise to world dominance during the early modern period.
The colonial enterprise and its attendant imperialism are by now accomplished facts, but what can we foresee going forward? Two things suggest themselves. First, the economic advantage conferred by quantitative knowledge is far from having been exhausted. On the contrary, the business world has been revolutionized in recent decades by the advent of big data. Those who are adept at exploiting it, such as the providers of social media platforms, have risen to a prominence similar to that enjoyed by the successful industrialists of the Gilded Age around the turn of the twentieth century, in a development known as the emergence of late capitalism. As we know, the pathologies associated with monopolistic business practices occasioned the reforms of the progressive movement. Many internet activists suppose something analogous to be in order in the current environment. But to be in a position to envision what steps to take so as to implement effective regulations requires that one first reflect upon the technical capacities set free by contemporary data science. The financial crisis of 2008, caused by a regulatory environment that permitted investment schemes based upon inept quantitative financial analysis to flourish and, in the event, to undermine the health of the entire economy, raises a warning flag. Crosby’s exploration of the first quantitative revolution that unfolded during the late Middle Ages to early modern period offers an excellent reference point for those who would understand better today’s complicated world and its possibilities, for good and for bad.
Second, one wonders whether the hypertrophy of quantitative methods accompanied by the ongoing demise of more qualitative expertise augurs well for the future. Certainly, the climate crisis may in large measure be attributed to the unintended side effects of the application of new technologies and the economic ventures they underwrite, supplanting established modes of doing things that, while perhaps less efficient in utilitarian theory, at least possessed the virtue of sustainability over the long term. Can humanity learn to take the measure, so to speak, of the quantitative and hold its adverse consequences in check by a parallel increase in sophistication of qualitative methods of knowing?
A concluding reflection, in which we adumbrate a few thoughts suggested by the present work but ranging well beyond what Crosby himself covers. What is clear from the history is that the invention of novel theoretical ideas together with a locus in praxis constitutes the precondition for fundamental advances. Crosby mentions some precedents: the late medieval computists, the seventeenth-century calculus. What about now, in the early twenty-first century? On the purely scientific front, the big developments seem to be in the areas of quantum computing and the omics revolution in biology. In practice, we have yet to experience the full ramifications of machine learning and big data science – in medicine, say (both of which are eminently practical and so receiving major support).
Therefore, conditions are ripe for exciting developments but where to turn for the new ideas? Taking the long view, we may look to the revolutionary concepts of number in modern mathematics, still characterized by the prevalence of a logical formalism seeking to found quantity in logic (the domain of intellect rather than of intuition) whose potential, one may judge, is far from having played itself out – for once one adopts a logical formalist perspective, one naturally arrives at Cantor’s transfinitum in which infinite quantities are just as conceivable and valid as finite – yet physics to date never makes use of infinity despite the fact that good functional analytic tools for going beyond metrizability exist (as in the theory of topological vector spaces, which are encountered in operator and spectral analysis, partial differential equations, probability and stochastic processes and mathematical economics). The reluctance to leave Hilbert space may perhaps explain why the program of constructive quantum field theory remains stalled at four dimensions, where no good existence proofs have been found out to date. After all, one can get only so far with the rough-and-ready heuristic tools of renormalization and the path integral, in the absence of fundamental understanding. Key breakthroughs in theoretical physics have always followed upon a deepening grasp of the pertinent pure mathematics, as with Leibniz and Newton’s differential and integral calculus with respect to classical mechanics, Gibbs and Heaviside’s vector analysis with respect to electrodynamics, Hilbert’s spectral theory with respect to atomic physics etc. Could then an analytically effective control over infinite quantity represent an organizing task for pure mathematics of the future?