“Abduction and Metaphysical Realism”

Abduction or retroduction is the real novelty that Peirce brought in the history of logic. According to its creator abduction should provide a scheme of rationality for hypotheses, that is for the moment in which thought grasps or conceives a new ‘reality’. In this sense abduction is a richer or – as Peirce said – a more ‘uberous’ (EP2: 472) kind of argumentation¹. The existence of this kind of argumentation was questioned in the subsequent history of logic. The ratio of abduction – the passage from consequent to antecedent – is a fallacy from the point of view of deductive rationality and it cannot even rely on a generic approval from common sense as induction does. In contemporary logic abduction has been completely abandoned and the field of hypothesis has been transferred to ‘pre-theoretical intuitions’. The closest field of inquiry that we can find today is the theory of the ‘inference to the best explanation’, which tries to define the choice that researchers make between alternative hypotheses. Peirce knew that there were many problems connected with the defense of abductive rationality. He himself changed the description of this argumentation many times, trying to keep a distance from deductive rationality as much as he could. This article intends to show these changes and to bring to light that the defense of abductive rationality requires the acknowledgement of a certain form of metaphysical realism. It is going to show also that in his later manuscripts Peirce hinted at elements that may give birth to a kind of metaphysics different from both the synechism professed in the last decade of XIX century and the scotistic realism of his late writings. The late formulation of abductive rationality can be also an ante litteram critique of any kind of reductionism of human rationality to a logical mathematical deductive rationality. At the end I will suggest that Peirce’s logical and metaphysical theory reaches a surprising attunement with Kripke’s theory of immediate reference. In both authors the problem of metaphysics undergoes a revival that starts from the real heart of logic when the latter reaches its extreme limits or possibilities.