  Recently, Brukner and Zeilinger (2001) have claimed that the Shannon
information is not well defined as a measure of information in quantum
mechanics, adducing arguments that seek to show that it is inextricably tied to
classical notions of measurement. It is shown here that these arguments do not
succeed: the Shannon information does not have problematic ties to classical
concepts. In a further argument, Brukner and Zeilinger compare the Shannon
information unfavourably to their preferred measure, I(p), with regard to the
definition of a notion of `total information content'. This argument is found
unconvincing and the relationship between individual measures of information
and notions of `total information content' investigated. We close by
considering the prospects of Zeilinger's Foundational Principle as a
foundational principle for quantum mechanics
