  We argue that four-dimensional black hole evaporation inevitably produces an
infinite number of soft particles in addition to the thermally distributed
`hard' Hawking quanta, and moreover that the soft and hard particles are highly
correlated. This raises the possibility that quantum purity is restored by
correlations between the hard and soft radiation, while inclusive measurements
which omit the soft radiation observe the thermal Hawking spectrum. In theories
whose only stable particle is the graviton, conservation laws are used to argue
that such correlations are in principle sufficient for the soft gravitons to
purify the hard thermal ones.
