Universidade de Lisboa
The Fitch-Church Argument, the Knower Paradox and Paraconsistency
21 July 2017, 16:00
Faculdade de Letras de Lisboa
Sala Mattos Romão (Departamento de Filosofia)
Abstract: We surely do not know everything, but some philosophers have thought that every truth can be known – by following the right method (be it the Cartesian method, or ‘the’ scientific method). An interesting argument first published by Frederic Fitch, but most likely due to Alonzo Church, purports to show that those philosophers are wrong, and that there are necessary limits to what can be known by non-omniscient beings like us. For many people of a more realist persuasion, that there are unknowable truths is good news, so they tend to look favorably to the Fitch-Church argument. But the argument looks suspicious, because it performs a kind of modal collapse, allegedly showing that if every truth is knowable, then every truth is known – so it invites looking for ways to resist it. In this talk, I will examine one way in which the Fitch-Church argument may be blocked, namely by adopting a paraconsistent logic and a dialetheic view of knowledge, independently motivated by another important problem, the Knower Paradox (due to Richard Montague). The dialetheic approach to both problems faces some objections, which I will discuss. I will argue that dialetheism proves better as a solution to the Knower than as a solution to the more general knowability problem.
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