Rush Limbaugh fans have often heard the conservative talk radio host suggest that people who consider themselves politically moderate just can't make up their minds on important issues of the day.

A recent study about ideological differences which drive more liberals to seek Ph.D.'s than conservatives might offer some answers as to why that is.

Published by the American Enterprise Institute, "Left Pipeline: Why Conservatives Don't Get Doctorates" presented some pretty compelling ideas about what's causing the liberal bias problem at America's colleges and universities (emphasis added throughout):

Every year, self-identified liberals apply to Ph.D. programs in far greater numbers than do conservatives. However, the reasons for this ideological imbalance are far from clear. Those on the political right tend to regard academia's liberal slant as evidence of discrimination against conservatives. By contrast, those on the political left may conclude that their overrepresentation in the academy is due to superior intelligence and abilities.

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The ideological imbalance among college students is evident immediately in figure 1. The graph reveals that self-identified liberals outnumber conservatives by a substantial margin. Additionally, the figure shows that those on the political left are more likely to express an interest in pursuing a Ph.D.

Interestingly, the authors of the piece, Dr. Matthew Woessner and Dr. April Kelly-Woessner, are a married couple with disparate political views themselves. As the Chronicle of Higher Education wrote on Friday (emphasis added):

During a recent Thursday-morning get-together over scrambled eggs and toast, the conversation at Kuppy's [diner in Harrisburg, Pennsylvania] focused on the U.S. presidential election. As usual, Mr. Woessner's colleagues were taking shots at him. Why did he originally favor Rudy Giuliani? one [sic] of his colleagues wanted to know. "I really want to make sure I have a president who is going to bomb more countries," Mr. Woessner quipped.

It is the kind of over-the-top statement Mr. Woessner is famous for. The young professor relishes the role of conservative contrarian inside the liberal academy, a role that puts him in a distinct minority not only here but in higher education generally.

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In fact, Mr. Woessner gets along so well with Democrats that he married one. Ms. Kelly-Woessner teaches a course on women and politics, among others, at Elizabethtown College. She and Mr. Woessner didn't like each other at all when they first met at Ohio State. She even once told her future husband that she could never date a conservative. So when the couple announced their engagement, the director of their graduate program at Ohio State was stunned.

"They really were opposites," says Herbert F. Weisberg, chairman of the political-science department at Ohio State. "They were always debating each other."

Regardless of their political differences, the couple produced excellent work in this paper:

There is reason to assume that liberals and conservatives have different experiences in college. If critics of the academy are correct, the liberal enclave provides a chilly environment for conservatives. This may not even be the result of intentional discrimination. Rather, conservatives may simply find themselves to be in the minority and disconnected from the rest of the campus. This minority status may affect their assessments of the educational experience and their overall satisfaction with college. According to previous research, satisfaction with the college experience does help to predict whether a student will complete an advanced degree.

And here's the part Rush Limbaugh and his fans will love:

Variations in reported grades do not vary as a function of conservatism, but rather as a function of moderation. Moderates3 consistently report lower grades than do their liberal and conservative counterparts. Concerned that less intelligent students might have self-identified as moderates, simply because they did not comprehend the ideological classifications used in the survey question, we reclassified the respondents based on their answers to a battery of political questions included near the end of the student survey. We found that students who take objectively moderate positions on important political issues do earn lower grades than their ideological classmates do.

Interesting, wouldn't you agree? Maybe this suggests an errancy in the debate concerning intellect and ideology always centering on liberals and conservatives whilst typically ignoring moderates. As this election might be decided by folks not committed to one of the major political parties, maybe greater focus should be given to what makes a moderate tick rather than the inner-psychological workings of liberals and conservatives.

Of course, that wasn't the point of this paper:

Whatever the basis of ideological identification, however, the differences between liberals and conservatives translate into differences in policy attitudes, behaviors, and dispositions, not all of which have direct political implications. For example, liberals and conservatives tend to differ on measures of the widely-used NEO Personality Inventory.11 Liberals tend to score higher in creativity and excitement seeking, while conservatives outperform in orderliness and striving for achievement.12

It is reasonable to assume that these differences in personalities and values translate into differences in career goals. For example, if liberals and conservatives have different notions of authority, this would theoretically translate into liberals selecting careers that are less hierarchical and that allow greater personal autonomy. In fact, Lindholm argues that the need for autonomy, independence, and intellectual freedom is the most cited reason college professors give for choosing academic careers.13 These career goals would appear to be more commonly associated with liberal ideologies. Similarly, if liberals are more likely to value creativity, as Carney et al. suggests, they may be more likely to self-select into the arts and humanities, with the more practical conservatives opting for professional fields.14

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Only 9 percent of the far left and 18 percent of liberals major in professional fields, as compared to 33 percent of conservatives and 37 percent of the far right. Since liberals already outnumber conservatives among college students, this tendency for conservatives to congregate in professional degree programs means that liberals outnumber conservatives two to one in the humanities and social sciences - fields most associated with doctoral degrees.

The professors offered some suggestions for academia:

First, in light of our prior research, which shows that students react negatively to overt partisanship, professors within the social sciences and the humanities should make a special effort to depoliticize their classroom.18 This does not suggest that political science or history courses should be bland or noncontroversial. Rather, striving to present both ideological perspectives on contemporary issues and debates would likely reduce the conservatives' relative dissatisfaction with their social science and humanities classes. If conservatives enjoyed these courses more, we might see a rise in conservative majors and in Ph.D. candidates.

Second, since conservatives place an especially high priority on financial security and raising a family, the academy needs to make efforts to adopt more family-friendly policies.

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While a host of concrete indicators (overall satisfaction with college experience, grade point average, contact with faculty, etc.) do not tend to support the assertion that conservatives are frequently the victims of discrimination, academia may create an environment that appears hostile to young conservatives. Just as academic institutions have, in the pursuit of racial and ethnic diversity, taken great care to foster a climate of tolerance, so too, academic programs might consider how their doctoral programs might be made more inviting to ideological conservatives. Ultimately, the academy's relevance is dependent on its ability to recruit and retain scholars from every intellectual tradition.

Great points all. Unfortunately, not everybody agreed with the Woessner's conclusions. Ilya Somin over at the Volokh Conspiracy blog wrote Friday:

I am somewhat skeptical about the particular variables emphasized by the Woessners. If interest in making money were a crucial variable in steering conservatives away from academia, one would expect their representation to be much higher in high-paying academic disciplines such as law, where faculty members routinely make six figure salaries and often have extensive consulting opportunities. Yet the ideological imbalance in legal academia is very large and fairly similar to that in other academic fields.

In my view, a focus on raising a family should make academia more attractive to conservatives rather than less. Relative to other professional jobs, academic careers are actually quite family-friendly. Unlike most other professionals, professors have a high degree of control over their schedules. They can also do a much higher proportion of their work at home, which makes it easier to spend time with kids. Universities also tend to have extremely generous family leave policies for faculty. Moreover, universities often give substantial tuition discounts to children of their faculty - an important benefit for social conservatives with large families. Some schools even subsidize private secondary school tuition for faculty children.

Somin raised another issue that might be particularly relevant to libertarian readers:

Like other studies of academic ideology, the Woessner and Kelly-Woessner paper also suffers from the failure to consider libertarians separately from conservatives. As I discuss in this post, libertarians are about 10-15 percent of the general population and are likely to be disproportionately represented among non-liberals likely to be interested in pursuing academic careers. Relative to conservatives, libertarians are about 20% more likely to be college graduates (see Table 10 in the linked paper) and threfore more likely to be potential candidates for academic jobs.

Although I'm not aware of survey evidence on this point, I strongly suspect that libertarians are closer to liberals than to conservatives in their interests in doing research, developing a philosophy of life, and raising families. Yet libertarians are almost as underrepresented in academia as conservatives are. Certainly, they are nowhere close to constituting 10 percent of faculty in any field other than economics. It is possible that libertarians are more interested in making money than liberals are; the claim is often made, though I have yet to see any systematic study that proves or disproves it. But even if this stereotype is true, it doesn't explain why they aren't better represented in law and other high-paying academic fields.

Maybe after they read this piece the Woessner's will comment on how libertarians impact this equation. Stay tuned.

—Noel Sheppard is the Associate Editor of NewsBusters. Follow him at Facebook and Twitter.