Human minds reason very naturally in terms of
how believable (or `likely', or `probable')
are different hypotheses in the light of everything we know
about them (see e.g. [15]) and the
mathematical theory of how
beliefs are updated by new pieces of information
was basically developed in a monumental work of
Laplace exactly two hundreds years ago[16,17],
although nowadays this way of reasoning goes under the name
*Bayesian*. This approach considers valid sentences such as
``probability that the CDF bump is a fluke'',
``probability that the Higgs boson mass is
below 130 GeV,''^{9} and similar,
all expressions that refer to
``a problem in the probability of causes, [...]
the essential problem of the experimental method''[19]:
from the observed effects we try to rank in probability
the alternative causes that might have produced them.

Giulio D'Agostini
2012-01-02