The instrumental character of Francis Bacon’s natural and experimental histories was often noted, but never fully investigated. In this paper I aim to reconstruct the theoretical and methodological background which supports this feature. I claim that we can read large parts of the second book of Bacon’s Novum organum as a guide to laboratory practices; and that it was read in this manner by some of Bacon’s seventeenth century followers. Key to this guide is Bacon’s theory of prerogative instances which, (...) in turn, provides the grounding for a whole theory of instruments of detection and instruments of measurement. I show, in particular, how Bacon suggested that such instruments can be used for ‘charting’ virtues and powers; a process in which instruments of detection can be transformed into instruments of measurement. I also show that Bacon’s views on instruments entail an elaborated conception of measurement which departs from the ethos of artisanal perfection. Instead of pursuing the ‘best results’, Bacon’s instrumental natural and experimental histories aim to offer a large enough corpus of correlations, estimates and calculations which, taken together, can represent more or less accurately changes and variations of natural virtues and powers. (shrink)

This essay explores seventeenth- and early eighteenth-century programs of natural inquiry where conjecture—an uncertain category of knowledge—played a vital role in the advancement of the sciences. It shows how early modern investigators used conjectures as a bridge between knowledge and ignorance and the process of conjecturing as a way to expand the mental state of inquiry. In publishing their conjectures, they were heeding Francis Bacon’s call to inspire hope and urge fellow experimenters to continue researching complex natural phenomena. Fellow investigators (...) could help to test, verify, revise, invalidate, or propose new inferences in a dialectical, collaborative process. The author argues that, by the eighteenth century, public conjecturing marked a particular kind of broad-minded experimental philosopher. This essay situates conjectures within agnotology—the study of culturally produced ignorance—and Baconian communication of knowledge and ignorance. It explores the philosophical and moral tensions investigators navigated when specifying nature’s unknowns. (shrink)