The Reasoning Process, Deduction, Induction and Pattern Recognition

Mark walks through a model of the reasoning process. Information comes from referrals, other health professionals, medical records, investigations and above all the subjective and physical examination. The clinician must first perceive what is relevant, then interpret each answer and test, form hypotheses, synthesize the information and test hypotheses with further questions and tests, building an evolving understanding of the person and their problem. He then introduces two types of inference. Deduction applies accepted criteria, such as confirming a neuropathic problem through specific testing, and represents slow reasoning. Induction generalizes from limited information without further testing, as when watching a stranger limp, and represents fast reasoning and pattern recognition. Experts use fast reasoning with familiar problems, such as recognizing an anterior talofibular ligament sprain from the mechanism. It is efficient but depends on a strong knowledge base and carries a greater risk of error, so slow reasoning is needed as a backup.