Induction, Experiment, and the New Method

In Book II of the Novum Organum, Bacon sets out his positive alternative to Aristotelian syllogistic reasoning: a method of induction he presents as radically different from the loose, hasty generalization ("induction by simple enumeration") he associates with ordinary popular reasoning and with much prior natural philosophy. Bacon's induction proceeds instead by the systematic compilation of "tables and arrangements of instances" — a Table of Presence, listing cases where a given phenomenon (his central worked example is heat) occurs; a Table of Absence in Proximity, listing closely similar cases where the phenomenon is nonetheless absent; and a Table of Degrees, or Comparison, tracking cases where the phenomenon varies in intensity. By comparing these tables, the inquirer performs what Bacon calls the "exclusion" or elimination of circumstances that do not reliably accompany the phenomenon, gradually narrowing in on its "form" — for Bacon, not a Platonic or Aristotelian formal cause in the traditional metaphysical sense, but the underlying physical structure or law responsible for producing the observed nature. In his own example, Bacon concludes that the "form" of heat is a kind of expansive, restrained motion of the smaller particles of a body — a conclusion that anticipates, if only qualitatively, the later kinetic account of heat as molecular motion, though Bacon reaches it through orderly comparison of instances rather than any actual physical experiment of his own devising.