The "Reasonable Man" and other legal standards

In the common law of negligence, an individual breaches the duty of due care if she fails to act as would a "reasonable man" under the circumstances. A natural question, first posed by Rubinstein [8], is whether the "reasonable man" can be derived from the views of actual agents. Rubinstein introduced an axiomatic model and showed that there does not exist a non-dictatorial aggregation method which satisfies several normatively appealing properties. I introduce a new model based on a different understanding of the "reasonable man" and provide a characterization of the "union rule", the most inclusive view of reasonableness satisfying a basic Pareto criterion. The union rule requires that a jury must unanimously agree to find a defendant liable for negligence.