Structural Nonrealism and Quantum Information

Abstract

The article introduces a new concept of structure, defined, echoing J. A. Wheeler's concept of "law without law," as a "structure without law," and a new philosophical viewpoint, that of structural nnnrealism, and considers how this concept and this viewpoint work in quantum theory in general and quantum information theory in particular. It takes as its historical point of departure W. Heisenberg's discovery of quantum mechanics, which, the article argues, could, in retrospect, be considered in quantum-informational terms, while, conversely, quantum information theory could be seen in Heisenbergian terms. The article takes advantage of the circumstance that any instance of quantum information is a "structure"--an organization of elements, ultimately bits, of classical information, manifested in measuring instruments. While, however, this organization can, along with the observed behavior of measuring instruments, be described by means of classical physics, it cannot be predicted by means of classical physics, but only, probabilistically or statistically, by means of quantum mechanics, or in high-energy physics, by means of quantum field theory (or possibly some alternative theories within each scope). By contrast, the emergences of this information and of this structure cannot, in the present view, be described by either classical or quantum theory, or possibly by any other means, which leads to the concept of "structure without law" and the viewpoint of structural nnnrealism. The article also considers, from this perspective, some recent work in quantum information theory.