Judging Actions on the Basis of Prima Facie Duties. The case of self-driving cars

Piotr Kulicki, Robert Trypuz

DOI: http://dx.doi.org/10.12775/LLP.2019.006


The need for a logic that allows us to reason about conflicting and non-conflicting norms has recently emerged in the domain of self-driving cars. In this paper we propose a formal model that supports moral decisions making by autonomous agents such as for example autonomous vehicles. Such a model – which we call a “Deontic Machine” – helps resolve both typical and atypical moral and legal situations that agents may encounter. The Deontic Machine has two sources of inspiration. The first one is W.D. Ross’s theory of prima facie norms and the other one is a deontic multi-valued logic. The main contribution of this paper is bringing together conceptual and technical tools of deontic logic to show how they can be used to control or assess the behaviour of a self-driving car.


autonomous agents; self-driving cars; conflict of norms; multi-valued deontic logic; practical reasoning; prima facie norms; Prolog

Full Text:



Belnap, Nuel, “A useful four-valued logic”, pages 8–37 in J.M. Dunn and G. Epstein (eds.), Modern Uses of Multiple-Valued Logic, Springer, 1977.

Boella, Guido, and Leendert W.N. van der Torre, “A game-theoretic approach to normative multi-agent systems”, in Normative Multi-agent Systems, 2007. URL http://icr.uni.lu/leonvandertorre/papers/normas07a.pdf

Contissa, Giuseppe , Francesca Lagioia and Giovanni Sartor, “The ethical knob: Ethically-customisable automated vehicles and the law”, Artif.Intell. Law 25, 3 (2017): 365–378. DOI: http://dx.doi.org/10.1007/s10506-017-9211-z

Craven, Robert, “Policies, norms and actions: Groundwork for a framework”, Technical report, Imperial College, Department of Computing, 3 2011.

De Haan, Jurriaan, “The definition of moral dilemmas: A logical problem”, Ethical Theory and Moral Practice 4, 3 (2001): 267–284. DOI: http://dx.doi.org/10.1007/10.1023/A:1011895415846

Goble, Lou, “A logic for deontic dilemmas”, Journal of Applied Logic 3, 3–4 (2005): 461–483. DOI: http://dx.doi.org/10.1007/10.1023/10.1016/j.jal.2005.04.004

Hansen, Jörg, “Deontic logics for prioritized imperatives”, Artif. Intell. Law 14, 1–2 (2006): 1–34. DOI: http://dx.doi.org/10.1007/s10506-005-5081-x

Hars, Alexander, “Top misconceptions of autonomous cars and self-driving vehicles”, 2016. URL www.inventivio.com/innovationbriefs/2016-09

Holbo, John, “Moral dilemmas and the logic of obligation”, Americal Philosophical Quarterly 39, 3 (2002): 259–274.

Horty, John F., “Moral dilemmas and nonmonotonic logic”, Journal of Philosophical Logic 23, 1 (1994): 35–65. DOI: http://dx.doi.org/10.1007/BF01417957

Horty, John F., Agency and Deontic Logic, Oxford University Press, Oxford, 2001.

Kulicki, Piotr, and Robert Trypuz, “Multivalued logics for conflicting norms”, pages 123–138 in O. Roy, A. Tamminga and M. Willer (eds.), Deontic Logic and Normative Systems, 13th International Conference, DEON 2016, 2016.

Sartor, Giovanni, “Normative conflicts in legal reasoning”, Artif. Intell. Law 1, 2 (1992): 209–235. DOI: http://dx.doi.org/10.1007/BF00114921

Taylor, Michael, “Self-driving mercedes-benzes will prioritize occupant safety over pedestrians”, October 2016. URL http://blog.caranddriver.com/self-driving-mercedes-will-prioritize-occupant-safety-over-pedestrians/

U.S. Department of Transportation, National Highway Traffic Safety Administration, Federal Automated Vehicle Policy Accelerating the Next Revolution in Road Safety, 2016. US Federal policy concerning AV.

van Benthem, Johan, Davide Grossi and Fenrong Liu, “Priority structures in deontic logic”, Theoria 80, 2 (2013): 116–152. DOI: http://dx.doi.org/10.1111/theo.12028

Ross, W.D., The Right and the Good, Oxford University Press, Oxford, 1930.

ISSN: 1425-3305 (print version)

ISSN: 2300-9802 (electronic version)

Partnerzy platformy czasopism