Dr. Giulia Felappi, (University of Southampton): “There is no reason for the necessity of the ultimate principles of deduction.” Margaret MacDonald on Logical Necessity.

This talks aims at contributing to the recent enterprise of rediscovering Margaret MacDonald’s views, by focusing on her reflections on the necessity of logic, a theme that runs through many of her papers and reviews. As it has been noted, MacDonald was profoundly influenced by Peirce, the Vienna Circle’s positivists, Stebbing and Wittgenstein, in particular the one of the lectures he delivered in the mid 1930s in Cambridge. Those authors surely form the background against which she developed her own views on the necessity of logic. But in this paper we will not aim at discussing her claims to detect those influences. Rather, we will focus on MacDonald’s claims themselves, and the reasons she put forward to support them. We will see both MacDonald’s negative views about what the necessity of logic is not (§1), and her positive view about what it is and how it supports her claim that it is in fact irrational to ask for a reason for the necessity of logic (§2). We will conclude by considering what she would reply now to defenders of dialethism and paraconsistent logics, to better show how her view on the necessity of logic is different from others, such as David Lewis’s (§3).