Revisiting whether conservative and libertarian law professors are more productive than their peers

|The Volokh Conspiracy |

In a prior post I highlighted a new paper by James Phillips, forthcoming in the Harvard Journal of Law and Public Policy, exploring some of the potential explanations for the apparent lack of law professors with conservative and libertarian views. Among other things, Phillips's paper found that conservative and libertarian law professors are, on average, more productive or more frequently cited than their peers.

Phillips's paper prompted substantial discussion about his findings and their potential implications. Below is Phillips's response:

The dearth of conservative/libertarian law professors is often attributed to one of four main explanations, what I call the Greed, Interest, Brainpower, and Discrimination Hypotheses. One is always worried that a study of this nature will result in some form of motivated reasoning or confirmation bias on the part of readers, with conservatives/libertarians overstating its findings and ignoring its weaknesses, and liberals ignoring its findings and overstating its weaknesses. But that may be unavoidable.

The data I examine-individual-level professor qualifications, and annual publication and citation rates-allow for a better investigation of the last two hypotheses (Brainpower and Discrimination) compared to the first two hypotheses. The first two-Greed and Interest-are self-selection hypotheses. Conservatives and libertarians do not enter legal academia by their own choice, choosing to pursue more financially lucrative or personally rewarding career paths. The other two hypotheses are ones of barriers to entry, one legitimate (Brainpower) and one arguably not (Discrimination).

Comments have centered around three main points. First, the data are also consistent with one of the self-selection hypotheses. Second, conservatives/libertarians are more likely to get clerkships, undermining the findings some. Third, annual publication and citation rates aren't good measures of law professor ability or success, and if they were, wouldn't the market correct any discrimination? Let me address each in turn.

If the Greed Hypothesis is the sole explanation, then we could expect conservatives/libertarians to pursue careers where they could make the most money. Thus, the more capable would not enter legal academia since they could make more money as lawyers in private practice or business. But less capable conservatives/libertarians, particularly those on the low end of the distribution of ability, would be attracted to legal academia because they could make more money there than as a practicing lawyer. And assuming conservative/libertarian ability and the ability of others were identical, overlapping distributions, the few conservatives/libertarians who made it into legal academia would, on average, not be as successful or as well-qualified as their non-conservative/libertarian peers. But that's not what we find, at least among professors at the top 16 schools I collected data on-conservative/libertarian law professors publish more and are cited more at statistically significant levels.

The Interest Hypothesis is harder to get at with this data, but I think something can be said. If fewer conservatives/libertarians are interested in being a professor (not because of hostility, real or perceived, due to discrimination, but less academically inclined), and the Brainpower Hypothesis is not implicated, then the ability of conservatives/libertarians and others should have overlapping distributions, and the distributions of Interest and Brainpower should be uncorrelated. Thus, only conservatives/libertarians at the high end of the Interest distribution would go into academia. But they should not be distinguishable from non-conservatives/libertarians on ability or performance since that is uncorrelated from Interest. One could argue that interest and ability are highly correlated among conservatives/libertarians, but not among others, but then one needs some kind of plausible theoretical explanation for why the groups are different. I'm certainly open to such, but haven't seen it yet.

Alternatively, one could imagine that getting a law professor job and being successful at it is a function of both Interest and Brainpower (which makes sense since we tend to do better that which we are interested in). For Interest the distribution of conservatives/libertarians would be shifted to the left of Liberals (the irony!). And there would be some cut-off point, below which it is impossible to get to a law teaching job, which is marked on the graph below with an X.

Phillips Curve

X

Thus, while conservatives/libertarians may be able to match their peers on Brainpower, they're generally just squeaking in the door with Interest, and since law professor success is a combined function of both, they will be on the lower end of the distribution of measured success.

But that is not the case-on average they publish more and are cited more than their peers at statistically significant levels. One could posit that the distribution of Interest among conservatives/libertarians is bimodal, with the high-interest group shifted to the right of non-conservatives/libertarians, resulting in them outperforming their peers. But such a distribution seems unlikely and there's no empirical or theoretical explanation for (a) bimodal distribution of Interest; and (b) one group to have a bimodal distribution and the other to have a normal one.

Another critique is that conservatives/libertarians are more likely to get clerkships than their peers. For space reasons, let me just direct readers to footnote 122 in the paper where I deal with this, and note that when I drop the clerkship variables from the full regression model, the coefficient on publications for conservative/libertarian professors goes up slightly, from .52 to .56.

Finally, annual publication and citation rates are not perfect measures of ability. For example, one could publish a lot of junk: quantity is not quality. I did not measure journal rankings for two reasons. One, there are over 27,000 articles in my dataset, and I don't have RA funding. Two, it's unclear how accurate of a proxy a journal's ranking is for quality (and then see reason one). But I don't think a lack of a quality measure makes quantity meaningless. And given these are professors at the top 16 schools, they are unlikely to have gotten to and stayed at the top of the legal academy by publishing garbage.

As to citations, people could just cite each other, could be cited as an example of a bad argument, or could primarily publish in areas that are more likely to be cited. I didn't explore that, again due to time and money limitations. But conservatives/libertarians are less likely to go into Public Law, where citation rates are higher; my experience is that poor papers tend to be ignored rather than singled out; and the law is sufficiently niche that people do tend to be citing each other in any sub-field. Conservatives/libertarians probably due get somewhat of a bump in citation rates, though, because they are more likely to be a dissenting voice, and one often notes minority or opposing viewpoints.

As to the claim that the market should correct itself if conservatives/libertarians are so outperforming their peers, the question is, what's the market? The reality seems to be that current law faculties, when they go to make a purchase on the market, can indulge their tastes. As the paper discusses, the law school market is currently not directly rewarded for publication and citation rates. Maybe that's a good thing, but law schools will respond to what they're rewarded for, and currently there is little outside of indulging in one's "preference" for fellow faculty that law schools have to consider. Not that there aren't other considerations-certainly scholarly potential is a huge factor in making an offer to an applicant, but all things being relatively equal, one can then consider other factors in one's decision, such as political identity. After all, most of us do not get to pick our co-workers. If we did we would probably succumb to the human tendency of homophily-the love of like-and pick people more like us.

The study, as are all, is not without its limitations or weaknesses. And with this paper I cannot not claim to have proven or disproven any one of the four hypotheses. Social science and statistical analysis deals with probabilities, not absolutes. And one can draw a lot of explanatory lines through a single point. For instance, one could interpret the data to mean conservatives/libertarians are, on average, smarter or more able than their peers. But one should reject such an interpretation when one finds no empirical evidence of such in other contexts, and there exists no theoretical reason to so conclude. Hence the danger of acontextual and atheoretical interpretations of a single study.

Still, that doesn't mean that the findings do not make some explanations more likely and others less. At the end of the day what one can do is adduction-pick the most likely explanation based on the data. One can come up with different explanations of various degrees of likelihood for each of the phenomena I find. But there is one explanation that connects all of the data-the qualification, publication, and citation gaps-and is therefore the most likely explanation: some form of discrimination occurring, unconscious or otherwise.

But more studies are needed. Empirically investigating any phenomena requires triangulation-using multiple methodologies and datasets to see if one hypothesis is consistently supported. There are other ways to get at this, better ones than this dataset, which is a bit of backdoor method to explore the issue. The point is that while we don't sufficiently know yet why conservative/libertarian law professors are fewer in number, this study, the first to examine this issue, nudges us in a particular direction because the data are more consistent with a story of discrimination and less consistent with inability or self-selection. But it's still too early to tell definitively. And maybe more than one explanation is occurring. We need more data.