Galileo's Instruments of Credit: Telescopes, Images, Secrecy (review)

Mario Biagioli's follow-up to his celebrated book Galileo, Courtier comprises four substantial chapters, three of which have been published in earlier forms. Perhaps as a result of this genesis, the book is considerably less coherent thematically than its predecessor, which focused on Galileo in his guise as a client of powerful patrons, whether the Grand Duke of Tuscany or the pope, and used that persona as a powerful explanatory resource in accounting for aspects of Galileo's famous career as a promoter of Copernicanism. Where the previous book did not notably engage with Galileo's Sidereus nuncius of 1610, this one does so closely, as well as considering the work on sunspots and Galileo's strategies in agitating in favor of Copernicanism prior to its censure by the Catholic Church in 1616.

The theoretical or interpretive stances in each chapter are quite diverse, despite occasional remarks intended to relate them to one another. In his first chapter, Biagioli focuses on distance as a functional element in the establishment of credit for Galileo and his new discoveries in 1610. He contrasts the resultant imperfect or partial knowledge available to the Medici court or Kepler who were separated from Galileo in Padua—and hence relied on time-delayed and anticipated information—with the widespread practices of modern science as understood by sociologists, who stress the importance of established relationships of trust among scientists and the importance of successful replication in the establishment of truth-claims and the attendant credit for the original claimant. He argues that Galileo was positively reluctant to enable other astronomers to "replicate" his discoveries for fear that providing them with the technical wherewithal to do so (either by sending them one of his own telescopes or by providing detailed information on how to make them) would risk enabling them to preempt his own making of further such discoveries. Galileo wanted to maintain a virtual monopoly on telescopic astronomy for as long as he could, but without jeopardizing the credibility of his discoveries or his credit with the Medici, his patrons-in-waiting. Biagioli argues that Galileo in effect bootstrapped Medici provisional acceptance of his new discoveries into a more widespread preparedness to believe them, which in turn solidified his relationship to the Medici. Thus, Kepler endorsed Galileo's discoveries before he had been able to verify them, and, in general, the new discoveries met with surprisingly rapid acceptance despite their potential threat to orthodox cosmology.

The conflation in Biagioli's argument between "instrument" and "experiment"—needed to establish the contrast with Harry Collins's "experimenter's regress" associated with credibility in modern experimental science—perhaps renders the intended stark contrast between Galileo's world and that of modern science less sharp than it need be. Still, Biagioli presents an interesting emphasis on the functional role of distance and "partial perspectives" (a perhaps inexact terminological borrowing from Donna Haraway) in creating breathing spaces for the establishment of credibility. He also illustrates this with a quite separate examination of the reputation of the early Royal Society. The notion of "deferral" implicit here is made explicit in the book's final chapter, which uses Derridean notions of "deferral" and "supplements" to explain Galileo's brittle use of the trope of "the book of nature" in his controversies with theologians over issues of scripture versus astronomy.

The book's second and third chapters concern Galileo's techniques in the Sidereus nuncius (1610) and the exchanges with Christoph Scheiner over sunspots, published in 1613. In each case, Biagioli is concerned with showing how Galileo's use of images must be understood in terms of the issues and stakes implied in the controversial issues that he used them to address. The "inaccuracy" of Galileo's pictures of the moon are a function of the point that he wanted to establish with them, that the moon's surface was rough and in that sense non-Aristotelian. The high degree of realistic representation apparently found in Galileo...