Medical natural language statements uttered by physicians are usually
graded, i.e., are associated with a degree of uncertainty about
the validity of a medical assessment.
This uncertainty is often expressed through specific verbs, adverbs, or
adjectives in natural language.
In this paper, we look into a representation of such graded statements
by presenting a simple non-standard modal logic which comes with a
set of modal operators, directly associated with the words indicating
the uncertainty and interpreted through confidence intervals in the model
Our interest in such a formalization is related to the use of OWL as the
de facto standard in (medical) ontologies today and its weakness
to represent and reason about assertional knowledge that is uncertain or
that changes over time.
The approach is not restricted to medical statements, but is applicable
to other graded statements as well.