  The paper explains why an ontology of permanent point particles that are
individuated by their relative positions and that move on continuous
trajectories as given by a deterministic law of motion constitutes the best
solution to the measurement problem in both quantum mechanics and quantum field
theory. This case is made by comparing the Bohmian theory to collapse theories
such as the GRW matter density and the GRW flash theory. It is argued that the
Bohmian theory makes the minimal changes, concerning only the dynamics and
neither the ontology nor the account of probabilities, that are necessary to
get from classical mechanics to quantum physics. There is no cogent reason to
go beyond these minimal changes.
