Astrology buff and Google Health chief David Feinberg tells The Wall Street Journal patients will soon have to receive personalized clinical horoscopes based on their medical histories and inferences drawn from a growing pool of patient records, so we should take a hard look at what today’s health-tech proponents are really selling. Algorithms and data can fail unexpectedly, such as in finance, insurance, law enforcement, and education, where they can be highly discriminatory and destructive.