In defense of classical logic
LE3 .A278 2018
Bachelor of Arts
Conundrums such as the liar paradox have driven some philosophers to conclude that classical logic is faulty. In this thesis, I aim to defend classical logic against some of its most notable opponents: paraconsistent logics (including relevance logic) and intuitionistic logic. Examining the general strategies of nonclassical logicians’ critiques of classical logic, I respond to their normative arguments by challenging the idea that logic is normative. I then proceed to examine paraconsistent logic, showing that it relies on classically valid rules of inference, such as disjunctive syllogism, which it explicitly rejects. Suspecting that challenges to classical logic are ill-motivated, I argue that both dialetheism and intuitionism rest on misdiagnoses of nonlogical issues as matters of logic. Lastly I address the curious problem of 'unsupposables’, propositions that allegedly cannot be supposed for the sake of inferring. While the problem presents an interesting challenge to the classical conception of logical implication as necessary truth-preservation, it ultimately rests on the same error as dialetheism and intuitionism: it, too, seems to be motivated by nonlogical worries. I show with this thesis that some of the most frequently raised concerns about the supposedly paradoxical features of classical logic in fact arise from nonlogical considerations which do not warrant modifications to logic.
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