Answer Justification in Diagnostic Expert Systems - Part I: Abductive Inference and Its Justification

Answer justification refers to the ability of an expert system to explain how or why it arrived at certain conclusions (such as a patient\´s differential diagnosis or treatment recommendations). In this paper, we describe an "abductive" inference method suitable for use in medical expert systems. We then demonstrate how this method can support a clinically plausible form of answer justification in functioning expert systems. A companion paper (Part II) provides the technical details of how the answer justification method described in this paper is implemented, and compares it to previous answer justification methods developed during the last several years.