A prominent woman publicly takes a position on a controversial issue such as teacher tenure. A prominent man disagrees with her and in doing so says the following: “She is a good media figure because of her looks, but she doesn’t seem to know or understand anything about teaching and why tenure matters. . . . I know it sounds sexist to say that she is pretty, but that makes her telegenic, even if what she has to say is total nonsense.”

In this hypothetical scenario how quickly would the man be denounced by major women’s groups, called upon to apologize, and possibly have his employer pressured to force him to resign? In an age in which Twitter often serves as judge and jury, one can presume the answer is fairly quickly. But the scenario referenced above is not entirely hypothetical. Those comments were made about a prominent woman, former CNN journalist Campbell Brown, by another prominent woman, educational historian and advocate Diane Ravitch.

Brown is now an education advocate and Ravitch, in an attempt to dismiss her criticism of teacher tenure, employed one of the oldest tricks in the book. She did not dismiss Brown’s argument on its merits. She dismissed Brown’s right to make an argument at all — on the basis of her looks. When men do this to women it’s labeled sexism, and rightly so, and is cause for widespread outrage. But when women do it to other women, such behavior is either met with silence or a shrug, even though such attacks are just as damaging as those from men, perhaps even more so. ( Ravitch responded to critics of her remarks on Twitter not by apologizing to Brown, but by reiterating that she thinks Brown’s position lacks “logic,” according to New York Magazine.)

In a widely read piece for The New York Times, Amy Wallace  wrote about how attacks on appearance have become a regular part of the life of female journalists in the Internet age. Twenty years ago if someone disagreed with a piece you’d written he might fire off an angry letter to the editor. Today he can Google you and comment on your attractiveness on Twitter. Wallace’s piece spoke truth to power for those of us who have ever been attacked or physically threatened online because of our work (including yours truly), but the one thing her piece failed to do was cast a wide enough net regarding who is to blame.

There is certainly a heavy dose of misogyny aimed at women in the public eye, but plenty of it comes from fellow women. For instance, men did not ridicule Olympian Gabrielle Douglas’s hair. Women did. Similarly early in my on-air career women were more likely to tweet about the state of my hair – particularly if they disagreed with something I said. (I say early in my career because I no longer read Twitter mentions.) Although it isn’t taken as seriously, women lobbing ad hominem attacks at other women can have serious consequences.

While “Seinfeld” devoted an entire episode to men’s obsession with seeing “cat fights” between women, the issue is no laughing matter. Ravitch’s remarks validate every man who has ever believed it’s acceptable to dismiss a woman’s intellect because of how she looks. But Ravitch also did something else. She validated the age-old “us-versus-them” divide that starts between girls in middle school and, unfortunately, can last a lifetime. The divide that says you can be smart or attractive, but not both, and if you fall into one camp you are unlikely to be welcome in the other. This division, and the suspicion of other women it breeds, could be at least partly to blame for the fact that women constitute the majority of the population in the United States but not the majority of the seats in Congress. We’re too busy critiquing each other’s hair and makeup, or second-guessing each other’s intelligence based on our hair and makeup, to work together. All the while, the men keep laughing all the way to the bank, as well as the halls of power.

In a previous interview, political pollster David Paleologos told me that during his years of conducting focus groups and polls he has found women to be “extremely tough” on each other. On top of this, studies have shown that the more a female candidate’s appearance is mentioned in media, the more likely she is to lose voters.

So instead of investing all of our energy in policing the misogynistic behavior of men, why don’t we invest some of it in policing the misogynistic behavior of women? Better yet, why don’t we start with every little girl we know by sending this message loud and clear: You don’t have to like every girl you meet or be her friend, but no matter how much you disagree with her, critiquing her appearance is off limits.