One of the main functions of law should be to provide relatively predictable rules that allow people to order their affairs with as much certainty as possible. The development of patent law in the field of software, however, has not provided the relative predictability that minimizes unnecessary patent prosecution and litigation costs. The courts have not given much guidance on what constitutes an “abstract idea”2 but have made “abstract idea” one of the key criteria for subject matter eligibility under 35 U.S.C. § 101, and this situation has produced real-world detriments. Innovators waste money and time either seeking patents they should not seek or defending themselves from patents that should be invalid. This article proposes a new rule for software patent eligibility that could help b1ing more clarity to the field.