Of Habit and Abduction Preserving Ignorance or Attaining Knowledge? Lorenzo Magnani, Selene Arfini, Tommaso Bertolotti Abstract “Habit” is not an easy term in Peirce’s epistemology: on the one hand it often signifies the rule of action that is attained with the fixation of belief [Peirce, 1998a]; on the another hand, it is also described as an almost instinctual process that determines further reasonings, the element “by virtue of which an idea gives rise to another” [Peirce, 1958b, Vol. VII, Book II, p. 215]. Stressing the apparently wide separation between these two traits of habit in the epistemic continuum be- tween doubt and belief, we will be able to illustrate a) a knowledge-based kind of habit, for the analisis of which we will also exploit Gibson’s concept of “affordance” [Gibson, 1950], which also plays a pivotal role in the justification of the agent’s own beliefs; and b) an ignorance-based kind of habit, which will be proved as necessary for the beginning of thought, and which is at the base of the ampliative reasoning, condensed in another Peircean key topic (often qualified as “instinctual” in his writ- ings): abduction. 1 Introduction: The Double Meaning of “Habit” Among the terms composing Peirce’s theoretical lexicon, the “habit” is endowed with an undoubtedly strong logical, epistemological, and cognitive value which jus- tifies its various applications. Usually it expresses the idea of “some general prin- Lorenzo Magnani Department of Philosophy and Computational Philosophy Laboratory, University of Pavia, Pavia, Italy, e-mail: lmagnani@unipv.it, Selene Arfini, Department of Philosophy, Education and Economical-Quantitative Sciences, University of Chieti and Pescara, Chieti-Pescara, Italy e-mail: selene.arfini@gmail.com, Tommaso Bertolotti Department of Philosophy and Computational Philosophy Laboratory, University of Pavia, Pavia, Italy, e-mail: bertolotti@unipv.it 1