Abstract
A probabilistic interpretation of the wave function of the Universe is proposed in which ‘‘probability’’ and ‘‘unitarity’’ are inherently approximate concepts. Their validity is limited by the accuracy of the semiclassical approximation for the entire Universe. This approach (which is a logical extension of DeWitt’s) defines a positive-semidefinite probability distribution and satisfies the correspondence principle with classical cosmology and with quantum mechanics. In particular, one recovers the standard probabilistic interpretation of the wave function for a small subsystem of the Universe.