ABSTRACT :: In recent decades, the Patent and Trademark Office and the federal courts have dramatically expanded the scope of patentable subject matter-the set of inventions eligible for patent protection. Existing scholarship has taken a narrow view of this expansion. Scholars argue on efficiency grounds that without more meaningful limits on the scope of patentable subject matter, future invention will be impeded rather than encouraged. This Article takes a broader view of the subject matter inquiry, tracing its historical development and its changing theories of technology, from the patent system’s inception to the present. This Article demonstrates that through these theories of technology the subject matter inquiry has shaped the patent system’s vision of the social role and meaning of technology, and defined the social good that the patent law serves. While the early inquiry placed the patent system in the service of a broad array of social values, the current inquiry places it in the exclusive service of economic value. This change, in turn, has facilitated the expansion of patent rights into all aspects of human life. Recognizing the discontent that this expansion has caused, this Article proposes that we consider legislative reform of the subject matter inquiry to better align its theory of technology with that of contemporary society.