Women now account for at least 30 percent of all physicians, but men still account for less than 6 percent of the nursing profession. The percentage of women lawyers has almost doubled since 1985, but the percentage of women pilots has remained stuck at around 6 percent for the past half century. 

What accounts for the differences? 

Two sociologists highlighted in a recent article in The New York Times have a new theory about why some professions tend to become, and remain, populated mostly by people of one gender, type of personality, or political affiliation. In a working paper called "Why Are Professors Liberal?" Neil Gross and Ethan Fosse argue that the way we stereotype professions influences what kind of people want to pursue those lines of work--so that the stereotyping ends up becoming a self-fulfilling prophecy. 

Gross and Fosse's paper focuses mostly on a study they conducted to explore why university professors, as a group, contain a higher percentage of self-described liberals than the American population at large. After sifting through data from the General Social Survey of opinions and social behaviors from 1974-2008, they concluded that at least a significant part of the answer was that academia "has acquired such a strong reputation for liberalism and secularism over the past thirty-five years, few politically- or religiously-conservative students, but many liberal and secular ones, have formed the aspiration to become professors." Thus the gap remains unchanged. The paper also extends this theory as a possible explanation for gender imbalances in other professions, including nursing. 

It's an interesting theory. And it's entirely possible that social reputation and peer support or derision has something to do with the skewing of certain professions in terms of gender, race, or political affiliation. But if social stereotyping of professions were really such a powerful force, then the fields of medicine, law, business and all other once male-dominated professions should be still just as skewed as they ever were. After all, the social stereotyping of doctors, lawyers and executives as male was every bit as strong as any social stereotyping of professors as liberal. 

But all of those gender-skewed professions shifted dramatically despite those once-dominant stereotypes. Why? In large part, because women fought very hard to change that image. Women wanted to be doctors, lawyers, and business executives enough to fight against type. And slowly, our collective image of "type" began to change. 

So why hasn't that happened with nursing? Because, Gross and Fosse would undoubtedly say, men didn't aspire to that profession enough to force a change. Okay, but why? Because it's a typecast as a typically "female" job? Or could it be because the job of a nurse doesn't just suffer from an image problem, but is, in fact, a job with less status, pay, power or control than other options a man might have? 

My point is, people who don't fit the "norm" of a profession may be motivated to fight their way in if the profession in question offers something they want: power, prestige, control, pay, opportunity, freedom, or even fulfillment, however they define it. Fewer people may be motivated to fight their way into professions that reduce those options, or offer less of what they consider valuable. The once male-dominated professions into which women have made major inroads (medicine, law, business) offer more prestige, pay, and status than many of the fields women traditionally dominated (teaching, nursing, secretarial services, or social services). That's not an image problem. That's a very tangible difference. 

But what about the gap in pilot gender? It's a good question, because the job of a pilot offers far more status and pay than that of a flight attendant ... or many other professions in the world. I've pondered that one for years, without coming up with a good explanation. But a friend of mine recently offered a thought I hadn't considered before: being a pilot, like being a combat commander, involves physical challenge, effort, and risk. And while some women certainly welcome that kind of challenge, it may be that not enough women are drawn to it to appreciably change the demographics. Or that the physical risks cancel out the appeal of the status, pay, or other rewards the profession offers. But again, the physical challenges and risks of flying aren't an image problem. They're a very real part of the job. 

So how does that relate to the question of liberal-minded professors? It may be that conservatively-inclined young people are turned off by the idea of going into academia. But is it because of its stereotypical image? Or is it, perhaps, because of very real truths about the job: that it offers less pay, less status in our conspicuous-consumption world, and potentially less freedom (other than intellectual freedom) than other possible career paths? Or even because of other factors? Some people may, for example, unwittingly subscribe to the belief that  "real men" don't sit around contemplating ideas instead of accomplishing real things in the world--which would discourage young men, at least, from pursuing more academic careers. Is that stereotyping? Of course. But not about the liberalism of academia per se. 

Gross and Fosse note that although 80 percent of professors answer that a "meaningful career" is very important to them, 60 percent of the general public answers the same way. They dismiss the difference, but it seems noteworthy, at least, that four out of five professors rate a meaningful career that highly. It's not surprising--you certainly don't enter academia if you want to make a lot of money or climb some entrepreneurial ladder. Other things have to motivate you.

The two researchers acknowledge that other factors are undoubtedly part of the equation, as well. And the motivations, desires, influences and subconscious filters at work in both young people and educational and hiring institutions are nothing if not layered and complex. I also wouldn't argue that perceptions don't matter, in terms of young people's aspirations in the world. One of the strongest arguments for actively working to change the ethnic, gender, political or racial mix of a profession is to provide ample role models young people can identify with as they imagine their futures. 

But before concluding that political or gender stereotyping limits the ability of a profession's demographic to change, it's worth noting the examples that have already proven otherwise. It's like the light bulb joke I used to hear, back when I worked in the mental health field: How many psychiatrists does it take to change a light bulb? Answer: Only one. But the light bulb has to really want to change.