Version: v1, Published online: 1998
Retrieved July 15, 2020, from https://www.rep.routledge.com/articles/thematic/free-logics/v-1
We often need to reason about things that do not – or may not – exist. We might, for example, want to prove that there is no highest prime number by assuming its existence and deriving a contradiction. Our ordinary formal logic, however (that is, anything including standard quantification theory), automatically assumes that every singular term used has a denotation: if you can use the term ‘God’ – if that term is part of your language – automatically there is a denotation for it, that is, God exists. Some logicians have thought that this assumption prejudges too many important issues, and that it is best to get rid of it. So they have constructed logics free of this assumption, called ‘free logics’.
Bencivenga, Ermanno. Free logics, 1998, doi:10.4324/9780415249126-Y048-1. Routledge Encyclopedia of Philosophy, Taylor and Francis, https://www.rep.routledge.com/articles/thematic/free-logics/v-1.
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