Medical Epistemology

Abstract

Deductive approaches in medical decision-making have an air of certainty borrowed from philosophical deduction, as for example, in the hypothetico-deductive approach. However, deduction, although certain, is limited because it cannot contribute to new knowledge other than proving some claims to knowledge as false (using modus tollens). Syllogistic deduction requires modification to gain utility, such as the partial and practical syllogisms. However, these forms are logically invalid in that they do not ensure certainty in the conclusions. The partial syllogism can be rendered more certain by the use of probability. However, the necessity of a medical decision requires dichotomization of the continuous probability variable. A cutoff threshold applied to the probability is necessary to enable a dichotomous decision, such as whether to treat or not treat a patient. The practical syllogism introduces the notion of cause and effect, which also may influence medical decisions, although often in a counterproductive manner.