Judge Richard Posner’s opinion in Indiana Harbor Belt Railroad Co. v. American Cyanamid Co. offers an economic interpretation of Restatement (Second) of Torts Section 520, which imposes strict liability on actors who conduct abnormally dangerous activities. This paper, which was prepared for a University of Chicago Law Review Symposium in honor of Judge Posner, provides a critique of the opinion and argues that Judge Posner’s analysis is at many points unpersuasive. The problem lies in substantial part with the questionable logic of the Restatement criteria for the assignment of strict liability.