Today, Western medical science typically conceives of a disease as falling into one of three categories. The first consists of diseases with a single identifiable cause, like smallpox or strep throat—what scientists call a “specific disease entity.” The second consists of diseases that are (as we might say colloquially) “all in your head”—the convictions of illness known as “conversion disorder,” or plain old hypochondria, embodied by Woody Allen’s character in Hannah and Her Sisters, who is convinced first that he has a malignant melanoma, then that he has a brain tumor. (“Do you hear a
...more
