One of the oldest debates in American jurisprudence concerns the concept of “proximate cause.” According to so-called formalists, the legal concept of proximate cause is the same as the ordinary concept of “cause.” The legal question of whether a cause is proximate for the purposes of establishing tort liability, therefore, is an objective matter about the external world determinable by familiar descriptive inquiry. By contrast, legal realists think that issues of proximate causation are disguised normative questions about responsibility. As the realists William Prosser and W. Page Keeton put it, proximate cause is better called “responsible cause.”
Recent work in cognitive science has afforded us new insights into the way people make causal judgments that were unavailable at the time of the original debate between formalists and realists. We now have access to the results of systematic experimental studies that examine the way people ordinarily think about causation and morality. This work opens up the possibility of a very different approach to understanding the role of causation in the law—one which combines the attractive features of both formalism and realism without accepting their implausible consequences.
In addition to providing a model for interpreting the case law of proximate cause, this Article also introduces a new way of doing legal theory—a method we call “experimental jurisprudence.” Experimental jurisprudence is the study of jurisprudential questions using empirical methods. Jurisprudential disputes about proximate cause are especially ripe for empirical analysis because the debate revolves around whether the legal concept of proximate cause is the same as the ordinary concept of causation. Interrogating the ordinary concept of causation, therefore, should shed light on this question.