A central figure in the early years of the French Revolution, Nicolas de Condorcet (1743–94) was active as a mathematician, philosopher, politician and economist. He argued for the values of the Enlightenment, from religious toleration to the abolition of slavery, believing that society could be improved by the application of rational thought. In this essay, first published in 1785, Condorcet analyses mathematically the process of making majority decisions, and seeks methods to improve the likelihood of their success. The work was largely forgotten in the nineteenth century, while those who did comment on it tended to find the arguments obscure. In the second half of the twentieth century, however, it was rediscovered as a foundational work in the theory of voting and societal preferences. Condorcet presents several significant results, among which Condorcet's paradox (the non-transitivity of majority preferences) is now seen as the direct ancestor of Arrow's paradox.

A Huguenot exile in England, the French mathematician Abraham de Moivre (1667–1754) formed friendships with such luminaries as Edmond Halley and Isaac Newton. Making his living from private tuition, he became a fellow of the Royal Society in 1697 and published papers on a range of topics. Probability theory had been pioneered by Pascal, Fermat and Huygens, with further development by the Bernoullis. Originally published in 1718, The Doctrine of Chances was the first English textbook on the new science and so influential that for a time the whole subject was known by the title of the work. Reissued here is the revised and expanded 1738 second edition which contains the remarkable discovery that when a coin is tossed many times, the binomial distribution may be approximated by the normal distribution. This version of the central limit theorem stands as one of de Moivre's most significant contributions to mathematics.