The phrase “rule of thumb” doesn’t have the origins you think it has:

Update from a reader:

As a professional researcher in the legal field, I enjoyed that video greatly. However, I am terrified of sharing it with my friends for fear of being pilloried as a misogynist. When I tried to suggest, while in no way condoning his vicious rants, that Elliot Rodger’s actions were more those of a mentally ill person than a “natural result” of widespread hatred of women, my suggestion was so quickly and roundly dismissed in light of his “obvious” motives that I decided to politely bow out of further discussion. It seems that much of twenty-first century feminism has taken on many elements of religious fundamentalism, in this case using patriarchy and misogyny as its original sin. And like Islamic and Christian fundamentalists, the most faithful interpret the world through their central ideology and will not engage in any discussion that might hold it as less than absolute truth.