I discussed already in several previous posts a project on the application of deontic logic to the understanding of the Mīmāṃsā exegesis of the Vedas. Now, the project leader, Agata Ciabattoni, made me ponder about a question I should have considered long ago, namely whether someone else has been applying deontic logic to other Sacred Texts.

At first sight, I would have thought that this would have certainly been the case, given that Sacred Texts are, at least in part, prescriptive texts. Further, I have already mentioned the work of Dov Gabbay in formalizing the deontic logic of the Talmud. Nonetheless, I found less than I would have expected (thus, even more than usual, I would be happy to receive further suggestions from readers).

1. Philosophy of Dionysius the Areopagite: Modal Ontology, by Basil Lourié. In: Logic in Orthodox Christian Thinking, ed. by Andrew Schulman, Ontos, Frankfurt a. M. 2012, pp. 230–257.

   The article elaborates on the concept of necessity and possibility in Dyonisius Aeropagita and discusses whether his should be termed an alethic or a deontic logic. The main point is that according to Lourié’s interpretation, Dyonisius’ deontic logic states that only what is necessary is possible, so that necessity and possibility are co-extensive.

2. Simo Knuuttila has analysed in several articles (see the list below) the emergence of deontic logic in Middle Age and Pre-Renaissance thinkers, such Abelard, Thomas the Aquinas, Roger Roseth, Ockham, Duns Scotus and so on. He discussed in particular the definition of categories such as possibility and necessity and the conflict among obligations.

   The Emergence of Deontic Logic in the Fourteenth Century. In: New Studies in Deontic Logic: Norms, Actions and the Foundations of Ethics, edited by Risto Hilpinen, Synthese Library 152, Reidel 1981, pp. 225–250.
   with O. Hallamaa, Roger Roseth and Medieval Deontic Logic. In: Logique et analyse 149, 1995, pp. 75–87.
   with Tania Holopainen, Conditional Will and Conditional Norms in Medieval Thought. In: Synthese 96 (1993), pp. 115–132.

3. James William Forrester has published at least two books (see below) which are much less technical and confront, among other things, the conflicts which occur when Standard Deontic Logic is applied to Christian Theology (for instance, the idea that it is not the case that one ought to do something impossible contrasts, according to Forrester, to Augustine’s and Calvin’s ethics).
   Being Good & Being Logical: Philosophical Groundwork for a New Deontic Logic, Sharpe, Armonk 1996.
   Why You Should: The Pragmatics of Deontic Speech, University Press of New England, Hanover 1989.
4. Whatever Happened to Deontic Logic by Peter Geach. In: Logic and Ethics, edited by Peter Geach and Jacek Holówka, Kluwer, Dordrecht 1991, pp. 33–48

   This article discusses, among other things, paradoxes derived from Anselm of Canterbury and the so-called “Good Samaritan Paradox”. In case you don’t know it, the paradox is solved through the distinction between “Ought to do” and “Ought to be”, since it is certainly the case that one Ought to save someone who has been beaten by thieves, but it is not the case that one Ought to be beaten by thieves.

5. Deontological Square, Hexagon, and Decagon: A Deontic Framework for Supererogation by Jan Joerden. In: Logica Universalis 6.1–2 (2012), pp. 201–216.

   This article (which is too technical for me, thus please take the following with some caution) deals with the application of a deontic theory to Islamic law, with special regard to supererogation and to the ascriptions of praise and blame. The author is conversant with deontic logic, also ante litteram (the Aquinas, Leibniz, Moore, Meinong).

6. Defeasible Logic in Contemporary Bioethics. On the Relevance of Both Casuistry and Islamic Itjihad, by Norman K. Swazo. In: Co-Existing in a Globalised World: Key Themes in Inter-Professional Ethics, edited by Hassan Bashir, Philipp W. Gray and Eyad Masad, Lexington Books, Plymouth 2013, pp. 1–27.

   This article discusses two corpora somehow akin to the Talmud (see my comments below) and their relevance for a case-by-case analysis, which is probably unavoidable in the case of bioethics. It contains also a short depiction of Islamic deontic logic, with its five categories (compulsory, recommended, permissible, unadvised, forbidden).

You might have noticed that seemingly no one but Gabbay and his colleagues tried to apply deontic logic to the concrete analysis of specific statements as found in a given Sacred Text. Why so?

I have no precise answer and it might be only due to the fact that the topic was not deemed to be interesting enough. Should one, however, insist, I could only dare a tentative explanation, namely that deontic logic as we know it originated and developed in a Lutheran environment (namely in Georg von Wright’s Scandinavia). Thus, its main authors were not aware of anything comparable to the Talmud Gabbay could analyse, namely a text in which the prescriptions of a given Sacred Text are carefully analysed, discussed, contrasted and so on. Perhaps the Jesuits’ tradition of Casuistry could have been seen as somehow paralleling the Talmud, but it was only accepted within Catholicism (and violently scolded by Lutheran theologians, if I remember correctly). It is no surprise that Islamic law (and Casuistry, as in the last item cited) build, by contrast, a good example for deontic investigations. The Buddhist Vinaya would have also been an interesting topic of investigation, but to it applies the general lack of team work among Western scholars and experts of Sanskrit, Pāli, Chinese, Tibetan and so on.

What did I miss?

On authors working on Mīmāṃsā deontics, see this post. On our project in general, see this one.
In case you wrote an article on deontic logic as applied to the Quran, or the Pāli Canon, or Matthew’s Gospel and so on, and I did not mention you: I am sorry. Please send me the details and I will be happy to read it and update the post.