According to Ian Hacking’s Entity Realism, unobservable entities that scientists carefully manipulate to study other phenomena are real. Although Hacking presents his case in an intuitive, attractive, and persuasive way, his argument remains elusive. I present five possible readings of Hacking’s argument: a no-miracle argument, an indispensability argument, a transcendental argument, a Vichian argument, and a non-argument. I elucidate Hacking’s argument according to each reading, and review their strengths, their weaknesses, and their compatibility with each other.

The idea that nature is governed by laws and that the goal of science is to discover and formulate these laws, rose to prominence during the Scientific Revolution of the seventeenth century. It was manifestly held by the most significant actors of that revolution such as Galileo, Descartes, Kepler, Boyle, and Newton. But this idea was not new. In fact, it made an appearance in the Middle Ages, and it is likely to have emerged already in Antiquity.1In this paper we (...) pay close attention to the concept of law of nature in the writings of Roger Bacon, the outspoken Franciscan who promoted experimental science. We will be using Bacon as a test case to show that long before the... (shrink)