John Stuart Mill’s On Liberty is the classic argument that all views should be freely expressed–by people who sincerely hold them–because unfettered debate contributes to public reasoning and learning. For Mill, controversy is good. However, he acknowledges a complication:

The cessation, on one question after another, of serious controversy, is one of the necessary incidents of the consolidation of opinion; a consolidation as salutary in the case of true opinions, as it is dangerous and noxious when the opinions are erroneous (Mill 1859/2011, 81)

In other words, as people reason together, they may discard or marginalize some views, leaving a narrower range to be considered. Whether such narrowing is desirable depends on whether the range of views that remains is (to quote Mill) “true.” His invocation of truth–as opposed to the procedural value of free speech–creates some complications for Mill’s philosophical position. But the challenge he poses is highly relevant to our current debates about speech in academia.

I think one influential view is that discussion is mostly the expression of beliefs or opinions, and more of that is better. When the range of opinions in a particular context becomes narrow, this can indicate a lack of freedom and diversity. For instance, the liberal/progressive tilt in some reaches of academia might represent a lack of viewpoint diversity.

A different prevalent view is that inquiry is meant to resolve issues, and therefore, the existence of multiple opinions about the same topic indicates a deficit. It means that an intellectual problem has not yet been resolved. To be sure, the pursuit of knowledge is permanent–disagreement is always to be expected–but we should generally celebrate when any given thesis achieves consensus.

Relatedly, some people see college as something like a debate club or editorial page, in which the main activity is expressing diverse opinions. Others see it as more like a laboratory, which is mainly a place for applying rigorous methods to get answers. (Of course, it could be a bit of both, or something entirely different.)

In 2015, we organized simultaneous student discussions of the same issue–the causes of health disparities–at Kansas State University and Tufts University. The results are here. At Kansas State, students discussed–and disagreed about–whether structural issues like race and class and/or personal behavioral choices explain health disparities. At Tufts, students quickly rejected the behavioral explanations and spent their time on the structural ones. Our graphic representation of the discussions shows a broader conversation at K-State and what Mill would call a “consolidated” one at Tufts.

A complication is that Tufts students happened to hear a professional lecture about the structural causes of health disparities before they discussed the issue, and we didn’t mirror that experience at K-State. Some Tufts students explicitly cited this lecture when rejecting individual/behavioral explanations of health disparities in their discussion.

Here are two competing reactions to this experiment.

First, Kansas State students demonstrated more ideological diversity and had a better conversation than the one at Tufts because it was broader. They also explicitly considered a claim that is prominently made in public–that individuals are responsible for their own poor health. Debating that thesis would prepare them for public engagement, regardless of where they stand on the issue. The Tufts conversation, on the other hand, was constrained, possibly due to the excessive influence of professors who hold contentious views of their own. The Tufts classroom was in a “bubble.”

Alternatively, the Tufts students happened to have a better opportunity to learn than their K-State peers because they heard an expert share the current state of research, and they chose to reject certain views as erroneous. It’s not that they were better citizens or that they know more (in general) than their counterparts at KSU, but simply that their discussion of this topic was better informed. Insofar as the lecture on public health found a receptive audience in the Tufts classroom, it was because these students had previously absorbed valid lessons about structural inequality from other sources.

I am not sure how to adjudicate these interpretations without independently evaluating the thesis that health disparities are caused by structural factors. If that thesis is true, then the narrowing reflected at Tufts is “salutary.” If it is false, then the narrowing is “dangerous and noxious.”

I don’t think it’s satisfactory to say that we can never tell, because then we can never believe that anything is true. But it can be hard to be sure …

See also: modeling a political discussion; “Analyzing Political Opinions and Discussions as Networks of Ideas“; right and left on campus today; academic freedom for individuals and for groups; marginalizing odious views: a strategy; vaccination, masking, political polarization, and the authority of science etc.