How do we know that objects continue to exist when we aren't perceiving them? I've always liked Lady Mary's way of putting the matter:
Essays on the Perception of an External Universe And Other Subjects Connected with the Doctrine of Causation. By Lady Mary Shepherd,. By Mary Shepherd
Of course, this requires an account of causation that allows us to go beyond experience, which some empiricist approaches would reject. But there are reasons for rejecting such approaches, anyway.