Experiments in the Making: Instruments and Forms of Quantification in Francis Bacon’s Historia Densi et Rari

The Historia densi et rari, published posthumously in 1658, is probably Francis Bacon’s most complex natural and experimental history. It contains observations and experimental reports, quantitative estimates and tables, and theoretical and methodological considerations, in a structure which has never been fully investigated. I provide here a fresh reading of this text from the perspective of scientific practices. I claim that Historia densi et rari represents a quantitative and instrumental investigation assembled with the help of Bacon’s philosophy of experiment as developed in the Novum organum. I first discuss the role played in the Historia densi et rari by the various instances of special power in delineating the object of research. I then analyze the ways in which a special class of instances of special power, the “mathematical instances,” are used in the Historia densi et rari to make the inquiry both more precise, and more abstract. Bacon used mathematical instances to transform traditional recipes of pneumatics into quantitative, more general investigations into universal motions and processes. Finally, I discuss two examples of scientific practice at work: the attempt to use instruments to gradually define and clarify “proper” (i.e., scientific) notions of “rarefaction” and “condensation,” and the redefinition of a metaphysical concept (plica materiae) in instrumental and operational terms.

Experiment

Experiment, as a specific category of scientific activity, did not emerge until the Scientific Revolution of the seventeenth century. Seen primarily as an arbiter in theory choice, there was little, if any, analysis of experimental techniques or, the ways in which data become transformed into established facts. Philosophical analysis of experiment was typically simplistic, focusing on the role of observation alone as the foundation for experimental facts. This was challenged by Thomas Kuhn who stressed the importance of background theory and beliefs in all perception, including (its role in) scientific experiment. This interconnection between theory and experiment severely undermined the idea that experiment could stand as an independent and objective criterion for judging the merits of one theory over another. In the 1980s new philosophical analyses of experiment began to emerge, emphasizing the ways in which experiment could be seen to have a life of its own embodying activities that could supposedly be understood without recourse to theory. Factors important in the evaluation of experimental results as well as the ways in which laboratory science differs from its theoretical counterpart became the focus for a new history and philosophy of experiment. Consequently, further debates arose regarding the relationship of experiment to theory, and whether it is possible to provide a methodological framework within which experimental practice can be evaluated.

Philosophy of Experiment in Early Modern England: The Case of Bacon, Boyle and Hooke

Serious philosophical reflection on the nature of experiment began in earnest in the seventeenth century. This paper expounds the most influential philosophy of experiment in seventeenth-century England, the Bacon-Boyle-Hooke view of experiment. It is argued that this can only be understood in the context of the new experimental philosophy practised according to the Baconian theory of natural history. The distinctive typology of experiments of this view is discussed, as well as its account of the relation between experiment and theory. This leads into an assessment of other recent discussions of early modern experiment, namely, those of David Gooding, Thomas Kuhn, J.E. Tiles and Peter Dear.