Abduction versus closure in causal theories

摘要

There are two distinct formalizations for reasoning from observations to explanations, as in diagnostic tasks. The consistency based approach treats the task as a deductive one, in which the explanation is deduced from a background theory and a minimal set of abnormalities. The abductive method, on the other hand, treats explanations as sentences that, when added to the background theory, derive the observations. We show that there is a close connection between these two formalizations in the context of simple causal theories: domain theories in which a set of sentences are singled out as the explanatorily relevant causes of observations. There are two main results, which show that (with certain caveats) the consistency based approach can emulate abductive reasoning by adding closure axioms to a causal theory; and that abductive techniques can be used in place of the consistency based method in the domain of logic based diagnosis. It is especially interesting that in the latter case, the abductive techniques generate only relevant explanations, while diagnoses may have irrelevant elements.