Extending the technology
John quickly realized that the simple expert system technology used in X1Plus neither adequately represented decision-taking as practised by clinicians, nor managed the risks implicit in advising on safety-critical decisions. Critical clinical decisions often have to be taken despite incomplete or uncertain knowledge.
During the 80s, in a series of studies using medical students he adopted and refined a decision model based on qualitative reasoning and argumentation, which better reflected the approach many human clinicians take, and provided sound, defensible, decision advice.
His team implemented a range of applications using logic programming, including a major demonstration activating part of a published medical text book, The Oxford System of Medicine.
Crucially, the argumentation approach proved acceptable to practising doctors.