  The problem of interpreting quantum theory on a large (e.g. cosmological)
scale has been commonly conceived as a search for objective reality in a
framework that is fundamentally probabilistic. The Everett programme attempts
to evade the issue by the reintroduction of determinism at the global level of
a ``state vector of the universe''. The present approach is based on the
recognition that, like determinism, objective reality is an unrealistic
objective. It is shown how an objective theory of an essentially subjective
reality can be set up using an appropriately weighted probability measure on
the relevant set of Hilbert subspaces. It is suggested that an entropy
principle (superseding the weak anthropic principle) should be used to provide
the weighting that is needed.
