Because of the communicative function of propositions, Logic is a moral science about what ought to be said. The association with morality derives from the connection between Logic and Truth, and the social value of speaking the truth. Propositions are used rather than mentioned sentences, and so are not the platonically abstract objects they have often been taken to be. Instead they are social objects formed by a community's employment of language. So it is the public use of sentences that settles what they mean, and thereby their logic. The matter has a particular relevance to Graham Priest's non-classical views.
1 Haack, S., ‘The Justification of Deduction’, Mind 85 (1976), 112–119 CrossRefGoogle Scholar.
2 See, e.g. Haack, S., Deviant Logic, Fuzzy Logic: Beyond the Formalism, (Chicago University of Chicago Press, 1996)Google Scholar, Ch. 5.
3 Béziau, J-Y., ‘Paraconsistent Logic from a Modal Viewpoint’, Journal of Applied Logic 3 (2005), 7–14 CrossRefGoogle Scholar.
4 Priest, G.G., ‘The Logic of Paradox’, Journal of Philosophical Logic 8 (1979), 219–241 CrossRefGoogle Scholar.
5 Slater, B.H., ‘Paraconsistent Logics?’, Journal of Philosophical Logic 24 (1995), 451–454 CrossRefGoogle Scholar.
6 F. Berto, ‘A Modality Called “Negation”’, Mind (forthcoming).
7 Kaplan, D., ‘Demonstratives’ in. Almog, J., Perry, J., and Wettstein, H. (eds), Themes From Kaplan (Oxford: OUP, 1989)Google Scholar.
8 E.g. Bealer, G., Quality and Concept (Oxford: Clarendon, 1982)CrossRefGoogle Scholar.
9 Slater, B.H., ‘Non-Analytic Logic’, Philosophical Investigations 37 (2014), 195–207 CrossRefGoogle Scholar.
10 Op. cit. note 9.
11 Slater, B.H., ‘What Priest (amongst many others) has been missing’, Ratio 23 (2010), 184–198 CrossRefGoogle Scholar.
12 Slater, B.H., ‘Consistent Truth’, Ratio 27 (2014), 247–261 CrossRefGoogle Scholar.
13 Berto, F., ‘The Gödel Paradox and Wittgenstein's Reasons’, Philosophia Mathematica 17 (2009), 208–219 CrossRefGoogle Scholar.
14 Slater, B.H., ‘Natural Language Consistency’, Logique et Analyse 215 (2011), 409–420 Google Scholar.