Universal Moral Grammar: Theory, Evidence, and the Future
Georgetown University Law Center
Trends in Cognitive Sciences, April 2007
Georgetown Public Law Research Paper No. 954398
Scientists from various disciplines have begun to focus renewed attention on the psychology and biology of human morality. One research program which has gained attention and has been profiled in Science, Nature, The New York Times, and other publications is universal moral grammar (UMG). UMG seeks to describe the nature and origin of moral knowledge by using concepts and models similar to those used in Chomsky's program in linguistics. This approach is thought to provide a fruitful perspective from which to investigate human moral competence from computational, ontogenetic, behavioral, physiological, and phylogenetic perspectives.
In this forthcoming article in Trends in Cognitive Sciences, I outline a framework for UMG and describe some of the evidence supporting it, including recent findings in developmental psychology, legal anthropology, comparative criminal law, and cognitive neuroscience. I also propose a novel computational analysis of trolley problem intuitions, which draws on a diverse set of ideas and traditions, including lexical semantics, common law theory, the philosophy of action, and Marr's three-level approach to cognitive science. Finally, I distinguish UMG from the dual-process model of moral judgment advocated by researchers such as Joshua Greene, Jonathan Haidt, and Cass Sunstein. Unlike Greene, I argue that the critical issue in the theory of moral cognition is not whether moral intuitions are linked to emotions - clearly they are - but how to characterize the appraisal system those intuitions presuppose, and in particular whether that system incorporates elements of a sophisticated jurisprudence.
Chomsky transformed linguistics and cognitive science by showing that ordinary language is susceptible to precise formal analysis and by rooting principles of grammar in the human bioprogram. UMG holds out the prospect of doing the same for aspects of ordinary human moral cognition. Initial efforts to explain trolley problem intuitions within this framework suggest that individuals are intuitive lawyers capable of drawing intelligent distinctions between superficially similar cases, although their basis of doing so is often obscure. Future research on moral grammar should begin from this premise, moving beyond the limited example of trolley problems and other doctrinally marginal "dilemmas" to the core concepts of universal fields like torts, contracts, and criminal law, which investigate the rules and representations implicit in common moral intuitions with unparalleled care and sophistication. Chomsky emphasized that rigorous formulation in linguistics is not merely a pointless technical exercise but an important diagnostic and heuristic tool, because only by pushing a precise but inadequate formulation to an unacceptable conclusion can we gain a better understanding of the relevant data and of the inadequacy of our existing attempts to explain them. Likewise, Marr warned against making inferences about cognitive systems from neurophysiological findings without "a clear idea about what information needs to be represented and what processes need to be implemented." Cognitive scientists who take these ideas seriously and who seek to understand human moral cognition must devote more attention to developing computational theories of moral competence. Legal theory will play an important part in this process.
Number of Pages in PDF File: 10
Keywords: moral cognition, moral intuition, moral grammar, universal grammar, universal moral grammar, deontic logic, poverty of the stimulus, Socratic method, trolley problem, battery, double effect, descriptive adequacy, act tree, Chomsky, Marr, Greene, Haidt, Sunstein, legal theory, intuitive jurisprudence
JEL Classification: D63, D64, K00, K13, K14
Date posted: January 2, 2007