  The quantum theory of decoherence plays an important role in a pragmatist
interpretation of quantum theory. It governs the descriptive content of claims
about values of physical magnitudes and offers advice on when to use quantum
probabilities as a guide to their truth. The content of a claim is to be
understood in terms of its role in inferences. This promises a better treatment
of meaning than that of Bohr. Quantum theory models physical systems with no
mention of measurement: it is decoherence, not measurement, that licenses
application of Born's probability rule. So quantum theory also offers advice on
its own application. I show how this works in a simple model of decoherence,
and then in applications to both laboratory experiments and natural systems.
Applications to quantum field theory and the measurement problem will be
discussed elsewhere.

Quantum Physics;History and Philosophy of Physics