American universities pose a terrible threat to our prosperity and democracy.

All college graduates should be well equipped at critical thinking — the capacity to reach measured conclusions from available statements and data, independent of preconceived notions.

Although essential at every level of professional work, employers find that facility lacking in about four in 10 graduates.As alarming, the College Learning Assessment Plus found four years of college often adds little to students’ analytical abilities, even at many prestigious institutions like the University of Texas.

In the 1950s, freshman composition was an arduous rite of passage. Each week, students wrote themes, which were rigorously graded for grammar and logical structure. They learned not merely how to throw a subject against a verb but also how to think clearly and put aside personal biases.

Gradually, such rigor has been removed from required undergraduate curricula. These days, repeating faculties’ and administrators’ politically correct orthodoxy, and running off campus speakers whose views challenge their prejudicesare what passes for intellectual competence.

In a less technical era, a general education — with a major in anthropology or history — was enough to launch a career. These days something more practical like software engineering or finance is required for most students to succeed.

Too often faculty and administrators dupe students with nostrums like “you can accomplish just about anything with a humanities degree” and offer examples of alumni in their 40s and 50s with enviable careers.

They don’t tell students that those alumni graduated into a more robust, less technologically demanding job market, and were better equipped, by virtue of more rigorous curricula, for self-directed continuing education.

America can’t expect to compete internationally with such ill-prepared citizens.

As importantly, universities are undermining American civic values of tolerance and respect for due process.

Broadly understood norms requiring faculty to abstain from the most hideous hate speech have morphed into expansive campus codes and tribunals —essentially required by a 2011 Obama administration directive to universities — that investigate faculty for posing ideas students decide are homophobic, racially charged or otherwise discomforting.

The slightest and most innocent turn of phrase — or ideas that cause students to question any form of political correctness — can land faculty in the dean’s office and cost them their jobs or at the very least leave the wrongfully accused marginalized and ostracized.

All reminiscent of the Spanish Inquisition.

As a defensive mechanism, many instructors are removing material that challenges cultural norms, values and prejudices. A professor of film at CUNY has dropped “The Birth of a Nation” because it deals with racism and “Tootsie” because it brings up too many gender stereotypes.

Much is appropriately made of assaults on free speech, but those have morphed into broader attacks on the most essential element of academic freedom — the latitude to thoughtfully challenge — free from fear of retribution — widely accepted ideas about society and science.

In an op-ed, professors Amy Wax and Larry Alexander from the Universities of Pennsylvania and San Diego argued that the decline of a unifying culturethat valued hard work, self-discipline, child rearing in stable marriages, service to employers and community, and respect for authority greatly contributes to poor economic and social conditions among working-class whites and minorities. Colleagues responded with a firestorm of attacksand the usual invectives about racism.

Bowing to mob ruleand embracing vigilantism in lieu of due process, the law school dean removed professor Wax from a mandatory first-year course and asked her to take a leave of absence. Maybe it’s the dean and some of her colleagues who are in need of a timeout.

America is unique among nations, because it was founded on the idea of the fundamental sanctity of individual liberty and freedom of thought, and not as a place defined by a specific ethnic, language or religious identity. All that is needed to become an American is to embrace this basic creed and take up the shared responsibility to preserve it.

It is difficult to see how a civilization that puts so much stock in those values and equal treatment under the law can long survive when its young people are required to embrace such intolerance and are taught by example those accused of transgressions are entitled to no more due process than the mob rule of a fascist state.