  We introduce a formal distinction between contradictions and disagreements in
natural language texts, motivated by the need to formally reason about
contradictory medical guidelines. This is a novel and potentially very useful
distinction, and has not been discussed so far in NLP and logic. We also
describe a NLP system capable of automated finding contradictory medical
guidelines; the system uses a combination of text analysis and information
retrieval modules. We also report positive evaluation results on a small corpus
of contradictory medical recommendations.
