It has been suggested, on the one hand, that quantum states are just states
of knowledge; and, on the other, that quantum theory is merely a theory of
correlations. These suggestions are confronted with problems about the nature
of psycho-physical parallelism and about how we could define probabilities for
our individual future observations given our individual present and previous
observations. The complexity of the problems is underlined by arguments that
unpredictability in ordinary everyday neural functioning, ultimately stemming
from small-scale uncertainties in molecular motions, may overwhelm, by many
orders of magnitude, many conventionally recognized sources of observed
``quantum'' uncertainty. Some possible ways of avoiding the problems are
considered but found wanting. It is proposed that a complete understanding of
the relationship between subjective experience and its physical correlates
requires the introduction of mathematical definitions and indeed of new
physical laws.Comment: 27 pages, plain TeX, v2: missing reference inserted, related papers
from http://www.poco.phy.cam.ac.uk/~mjd101
