Causality in Medicine

In the words of the great astronomer John Frederick William Herschel [son of Friedrich Wilhelm, the scientist of great renown who, with his sister Caroline Lucretia, discovered the planet Uranus (1781), author of the fundamental text of philosophy of science Preliminary Discourse on the Study of Natural Philosophy (1830)], when a “mind” studies any phenomenon that gives rise to a sensation of wonder or even fear, then the next step must be to find a way to discover what produced that sensation. This, of course, is a hallowed tradition: the famous motto of Vergil comes to mind, “felix qui potuit rerum cognoscere causas” (Georgics, II, 490), that motto which paraphrases the well-known passage penned by Lucretius in his De rerum natura (III, 1072). This statement, however, must be revised when taken in a typically empirical context: the clearest indication that the “true cause” has been identified is when it not only provides an answer to the original question, but also offers an explanation of many other facts, sometimes exceeding even the wildest hopes of the original researchers. (It may even be that on re-examination what was originally thought to be evidence against a certain hypothesis may turn out to be quite the opposite).