  The quantum-mechanical description of the world, including human observers,
makes substantial use of entanglement. In order to understand this, we need to
adopt concepts of truth, probability and time which are unfamiliar in modern
scientific thought. There are two kinds of statements about the world: those
made from inside the world, and those from outside. The conflict between
contradictory statements which both appear to be true can be resolved by
recognising that they are made in different perspectives. Probability, in an
objective sense, belongs in the internal perspective, and to statements in the
future tense. Such statements obey a many-valued logic, in which the truth
values are identified as probabilities.
