It's a given that the number of conservative professors on campus is very small. What few there are probably exist solely in the economics department or in a few cases the law school. 

Lately, the idea of viewpoint diversity (sometimes called ideological diversity) has caught on among people on the right, especially as more woke politics is being exported by universities. This debate may have peaked last year when university presidents were called before congress to defend their handling of pro-Palestinian protests, but the basic idea that universities discriminate against conservatives has been around for a long time. Now there are efforts to do something about it in some states.

Calls for viewpoint diversity have been written into education laws proposed or passed in at least seven states, including Florida and Texas. In March, Indiana passed a law that curtailed diversity, equity and inclusion programs, while mandating that professors be regularly evaluated on whether their courses promote “intellectual diversity.” Failure to do so can be a firing offense, even for tenured faculty...

“There are plenty of people in and around academia — people in the center and even many on the left — who do think you need to broaden the range of political discourse on campus,” said Neil Gross, a sociologist at Colby College and the author of the book “Why are Professors Liberal and Why Do Conservatives Care?” “And that is combining with the efforts of folks on the right who have been going after higher education for a long time.”...

Academia has been seen as a liberal profession since the early 20th century, Gross writes in his book. Today, he says, it employs a higher percentage of liberals than nearly any other profession. While results vary by discipline and type of institution, most surveys suggest that only about 10 to 15 percent of faculty across the country are conservative.

The problem with having entire faculty departments made up entirely of far left people goes beyond the issue of fairness. College professors are supposed to produce knowledge, but how can they do that if their departments become an exclusive club shut off from contradictory ideas.

In his influential 1994 paper “Political Psychology or Politicized Psychology: Is the Road to Scientific Hell Paved With Good Moral Intentions?,” Philip E. Tetlock argued that the field was in danger of simply reproducing (or being seen as reproducing) favored political talking points. Too many researchers, he argued, were blind to the ways their biases were baked into their methodologies and premises, and the ways dissent was discouraged...

Tetlock is among the scholars who have questioned the validity of the Implicit Association Test, a widely used measure of unconscious prejudice. More recently, new research has challenged a widely cited earlier finding: that conservatives have a higher “negativity bias” — that is, they are more reactive than others to perceived threats and other negative stimuli.

That idea may give liberals the warm and fuzzies. But as Tetlock warns, “Be skeptical of all empirical claims but especially skeptical of those that make your community of co-believers feel good about themselves.”

Any group of like-minded academics is going to be more likely to pursue research that confirms their own views and less likely to find holes in their own arguments and theories. It takes work to counter and sift through counter-arguments and people are less likely to do that work if they fundamentally agree with what the research is claiming. Thus viewpoint diversity should produced better research while a lack of it leads to the kind of absurdist nonsense that was exposed by the grievance studies papers back in 2018.

There are some good comments on this one. Here's one of the best:

The problem on college campuses today isn't a dearth of conservative-leaning students and faculty.  The problem is the idea-smothering, discussion-terminating culture that puts enormous social pressure on students to conform, if only by remaining silent, to increasingly reductionistic ideology that seeks to explain history, economics, sociology, politics, and psychology through a polarizing lens that perceives human endeavor as essentially little more than a struggle between a numerically-smaller class of oppressors -- largely identified as Caucasian, European-derived, male, and heterosexual -- versus a numerically-larger class of the oppressed, being everyone else.

In so many words, woke culture is the problem. Here's another one.

As a recent older graduate from a supposedly elite university, this article largely reflects my experiences with the student community as well as faculty. Anyone with even a mildly centrist viewpoint, let alone an actual conservative viewpoint, was openly mocked, shouted down, or even kicked out of online discussion spaces. Professors and administrative staff too, sometimes subtly, sometimes not-so-subtly, displayed a clear bias towards certain viewpoints.

Lots of progressives sounding off with comments like this one suggesting conservatives are too dumb to work at universities.

Perhaps there are relatively few conservative professors at schools not because they are being discriminated against (the conservative culture of grievance and obsession with being oppressed never ceases to amaze), but because conservatism is necessarily a backwards-looking and data-denying ideology, which highly educated individuals like professors are often able to see through.

But back in the real world, this is how far-left dominance is maintained, not through intellect but bullying and implied threats.

I know a professor who is conservative working at a highly respected university who, out of fear for his job, takes lunch off campus on those occasions when he and his fellow conservative  colleagues intend to discuss politics. Can anyone reasonably believe that conservative viewpoints are shared openly in class in an environment such as this? There is no quantitative measure that’s going to capture this reality of intolerance on college campuses.

One more:

The issue more than needing conservatives is that entire areas of academia are dominated by the far left who see their role fundamentally as acitivists not scholars. This describes basically the entire fields of anthropology, English etc. it’s not that we need republican anthropology professors, it’s that there should ideally be people in these departments who are able to meaningfully question each others assertions rather than create an echo chamber of far left talking points.

As the woke ideology continues to spread on campus, we'll see more and more traditional liberals realize that it's not just conservative ideas being ruled off limits, it's anything that isn't part of the narrow (and ever-shrinking) far-left ideology.