  A scientific reasoning system makes decisions using objective evidence in the
form of independent experimental trials, propositional axioms, and constraints
on the probabilities of events. As a first step towards this goal, we propose a
system that derives probability intervals from objective evidence in those
forms. Our reasoning system can manage uncertainty about data and rules in a
rule based expert system. We expect that our system will be particularly
applicable to diagnosis and analysis in domains with a wealth of experimental
evidence such as medicine. We discuss limitations of this solution and propose
future directions for this research. This work can be considered a
generalization of Nilsson's "probabilistic logic" [Nil86] to intervals and
experimental observations.
