A New Conception of Science

Most scientists hold that theories are accepted and rejected on the basis of evidence, no metaphysical thesis being accepted permanently independently of evidence. But in physics only those theories are considered which are sufficiently simple, unified or explanatory, even though disunified rivals, potentially even more empirically successful, could always be formulated. This persistent preference for simple, unified theories means, it is argued, that physics makes a substantial, problematic metaphysical assumption about the universe, namely that it has a more or less unified dynamic structure. Physics would be more rigorous if this problematic, implicit assumption were made explicit, so that it can be criticized and, we may hope, improved.