Deductive Inference

“We hope you will find these thoughts of ours both interesting and useful.” These are words spoken to express an intention, a bearing in the mind of a person toward an object which is yet to be achieved. The readiest moment of human life involves the interplay of signs, ideas, and objects — more explicitly, the interrelation of signifying expressions, states and dispositions of the mind or person, and objects or objectives either actual or potential. Our work designing instruments to enhance the play of inquiry has attuned us to the themes of interpretation and intentionality which every inquiry seems to involve. We hear what sounds like familiar strains reaching us from the hermeneutic quarter. The purpose of this essay is to trace to their sources a few of these potentially common themes, to draw out one line of their historical development, and to gather what consequences they inspire for educational practice and continued inquiry.

There is normativity to inference, i.e. some inferences are flawed, while others are fine (in the sense that rationality is incompatible with too many flawed inferences, while good inferences transmit epistemologically valued things like justification and knowledge) so that a good deduction (but not a good abduction or induction) must be (at least) deductively valid. The purpose of this paper is to put forward an asnwer to the questions: what is an inference and when is an inference deductive rather than inductive, abductive, etc. These are questions that have not been properly addressed in the literature. Yet, they are not idle, for it directly bears on the question of what normative standards to apply to which inferences. Good deductive inferences need to be valid; inductive inferences, not. Without a clear line dividing deductive inference from other sorts of inferences, we run the risk of misdiagnosing the rationality or logical status of our inferences.

E' stata la consapevolezza delle molteplici prospettive aperte dalla ricerca attuale sull'errore a ispirare questo numero di Networks, che riprende in parte un convegno tenuto a Imperia nel giugno del 2004 (L'errore nella razionalità individuale e collettiva). Il volume non si propone di dare una trattazione sistematica dell'argomento, bensì di raccogliere vari suggerimenti e contributi provenienti da punti di osservazione diversi.
Contributi di: Vittorio Girotto, Giorgio Rampa, Matteo Bonifacio e Diego Ponte, Luca Beltrametti, Valeria Ottonelli, Cristina Bicchieri, Massimo Egidi