Experiment

Boyle was among the more eminent followers of the Baconian program. Many of the issues and difficulties faced by that program can be seen in his controversy with the philosopher Thomas Hobbes (1588–1679) over the character of knowledge in natural philosophy. For Boyle knowledge of nature should be descriptive and based on consensus. The aim of experimental inquiry had to be the establishment of matters of fact and not the discovery of their underlying causes. Hobbes, on the other hand, argued that knowledge should be demonstrative, causal, and necessary. Thus, the experimental production of artificial effects could not lead to true knowledge, because the inference from effect to cause is always hypothetical.

In the course of their controversy Hobbes and Boyle debated the implications of the latter's experiments with the air pump. By means of that instrument, Boyle had managed to create a vacuum. In defending his results, he claimed that his experiments were publicly performed and could be replicated at will. Hobbes disputed those claims and emphasized the artificiality of Boyle's results. Hobbes's critique was an instance of a more general skepticism toward scientific instruments, some of which created phenomena that did not exist in nature. For that reason, their legitimacy was contested. At issue was whether they revealed natural processes or produced artifacts and, thereby, distorted nature.

According to Steven Shapin and Simon Schaffer, the significance of the Boyle–Hobbes debate extended far beyond natural philosophy. Shapin and Schaffer made a fascinating case that the eventual establishment of the experimental "form of life" implicated wider social and religious issues. In particular, they argued that Boyle's experimental program was in tune with the need for order and consensus in Restoration England. The general validity of this thesis, however, is questionable. By the end of the seventeenth century the "experimental philosophy" had spread throughout continental Europe, where the social and religious conditions differed significantly from those in England.

The rise of experimental philosophy gradually undermined the identification of science with demonstratively certain knowledge. Experimental results came to be seen as only "morally" certain—that is, certain for all practical purposes. Explanatory hypotheses, on the other hand, came to be regarded as merely probable. The quest for certainty, though, was never entirely abandoned, as is testified to by Isaac Newton's work.