The Measure of Multitude: Population in Medieval Thought (review)

Biller has discovered a new subject, medieval demographic thought, and written the first book to explore medieval ideas about population. This is not a study of medieval demography, for which sources are poor,but a series of close readings of contemporary theologians to uncover possible reactions to issues concerning nuptiality and population levels. Confined to the period from 1100 to the 1340s, Biller has deniedhimelf the chance to study the main demographic event of theMiddle Ages, the plague of 1348 and its sequels. Nonetheless, no onewho studies the plague, famines, and numerous other topics in medieval history willbe able to ignore this ingenious and comprehensive study.

Biller has read widely in the works of medieval theologians and canon lawyers in order to explore how the rise of academic scholasticism in the twelfth century led to a greater interest in what we would call demographic thought. Always careful to avoid anachronisms, Biller knows that the concept of demography (indeed the very word) did not exist in this period. Just as we can explore medieval economic or scientific thought before the abstractions "the economy" or "science" became prevalent, some medieval thinkers became increasingly aware of how issues concerning levels of population affected subjects as diverse as marriage and the crusades.

Biller's sources are almost exclusively from the most educated levels of society. An occasional look at sermons does allow a faint reflection of how the majority of medieval people may have thought about issues like population density and fertility.

The book contains many original, striking findings and fresh perspectives. One new development in this period was the increasing historicization of marriage. Theologians thought hard about polygamy in Hebrew scripture and the much-proclaimed duty of all to marry and multiply. No longer playing by these rules, medieval thinkers began to see marriage as a fluid institution that changed over time and location. William of Auvergne in the thirteenth century was one of the first to make the connection between Muslim teachings about marriage and procreation and the populousness of their lands. St. Bonaventure looked closely at what we call the sex ratio and whether equal numbers of women and men were born into the world. Around 1300, more than one writer seemed aware of the high levels of population across Western Europe, except in Iberia. By then, many theologians had looked more closely at the propriety of avoiding offspring, the contemporary parlance for birth control.

Biller also pays attention to the translations of Aristotle's works and how his ideas entered medieval thinking about life spans and the ideal ages for first marriage. Aristotle concluded that women should marry at eighteen and men at thirty-seven or a little younger. This model partially applies to areas of southern Europe, but even some contemporary thinkers knew that women elsewhere married later, and that the age of marriage affected the eventual number of children in the family. Aristotle's marriage model forced commentators to look more closely at generations and life cycles as determining population levels, and his favorable views on infanticide found no medieval support.

Biller concludes with a close look at Florence in the early fourteenth century. Giovanni Villani's amazing statistical data about Florentine births, sex ratios, and population levels have engaged and perplexed scholars for decades. Thanks to Biller, we have an explanation and an intellectual context for Villani's interests. Biller's book has deepened by centuries the background to Thomas Malthus and the nineteenth- century rise of demography as a topic of study.