Abstract
The author, a physicist as well as a philosopher, uses the thought of Werner Heisenberg as a focus for examining the epistemological foundations of quantum theory. Though Heisenberg's earliest original insights were stimulated by Plato's Timaeus he soon swung over to Bohr's empiricism in developing and supporting the Copenhagen interpretation of quantum mechanics. His later philosophical reflections are markedly Kantian with irreducible physical invariants playing the role of Kant's necessary and universal laws. As Heelan sees it, an examination of the intentionality-structure of the scientist supplies the critical basis for judging the reality of the objects known through science. Though Heisenberg rejected the naive "empirical objectivity" of pre-quantum interpretations of science, his reflective evaluation of his own achievements is inadequate in explaining the formal objectivity of the objects known. By distinguishing the criterion of reality, rational affirmation, from the meaning of "reality," whatever is defined by the object in its formal sense, Heelan is able to develop a critical realism that assigns an ontological status to fundamental particles. "Main-line" philosophers of science may feel ill at ease with Heelan's phenomenological terminology of "intentionality-structure," "noema," and "horizon" and may object to his treatment of "meaning" and "language." But if they "bracket" these reservations they will find this book an unusually well-informed and penetrating study of the philosophical implications of modern physics.—E. M. M.