After Oct. 7, the public was shocked at what they saw and heard on America’s campuses.

Americans knew previously they were intolerant, leftwing, and increasingly non-meritocratic.

But immediately after Oct. 7 — and even before the response of the Israel Defense Forces — the sheer student delight on news of the mass murdering of Israeli victims seemed akin more to 1930s Germany than contemporary America.

Indeed, not a day goes by when a university professor or student group has not spouted antisemitic hatred. Often, they threaten and attack Jewish students, or engage in mass demonstrations calling for the extinction of Israel.

Why and how did purportedly enlightened universities become incubators of such primordial hatred?

After the George Floyd riots in 2020, reparatory admissions — the effort to admit diverse students beyond their numbers in the general population — increased.

Elite universities like Stanford and Yale boasted that their so-called “white” incoming student numbers had plunged to between 20 and 40 percent, despite whites making up 68-70 percent of the general population.

The abolition of the SAT requirement, and often the comparative ranking of high school grade point averages, have ended the ancient and time-proven idea of meritocracy. Brilliant high school transcripts and test scores no longer warrant admissions to so-called elite schools.

One result was that the number of Jews has nosedived from 20-30 percent of Ivy League student bodies during the 1970s and 1980s to 10-15 percent.

Jewish students are also currently stereotyped as “white” and “privileged” — and thus considered as fair game on campus.

At the same time, the number of foreign students, especially from the oil-rich Middle East, has soared on campuses. Most are subsidized by their homeland governments. They pay the full, non-discounted tuition rates to cash-hungry universities.

Huge numbers of students have entered universities, who would not have been admitted by the very standards universities until recently claimed were vital to ensure their own competitiveness and prestige.

Consequently, they are no longer the guarantors of topflight undergraduates and professionals from their graduate programs.

Faculty are faced with new lose/lose/lose choices of either diminishing their course requirements, or inflating their grades, or facing charges by Diversity/Equity/Inclusion commissars of systematic bias in their grading — or all three combined.

The net result is that there are now thousands of students from abroad, especially from the Middle East, far fewer Jewish students, and student bodies who demand radical changes in faculty standards and course work to accommodate their unease with past standards of expected student achievement.

And, presto, an epidemic of antisemitism naturally followed.

In such a vacuum, advocacy “-studies” classes proliferated, along with faculty to teach them.

“Gender, Black, Latino, feminist, Asian, Queer, trans, peace, environmental, and green”-studies courses demand far less from students, and arbitrarily select some as “oppressed” and others as “oppressors.” The former “victims” are then given a blank check to engage in racist and antisemitic behavior without consequences.

Proving to be politically correct in these deductive gut-courses rather than pressed to express oneself coherently, inductively, and analytically from a repertoire of fact-based knowledge explains why the public witnesses faculty and students who are simultaneously both arrogant and ignorant.

At some universities “blacklists” circulate warning “marginalized” students which professors they should avoid who still cling to supposedly outdated standards regarding exam-taking, deadlines, and absences.

All these radical changes explain the current spectacle of angry students citing grievances, and poorly educated graduates who have had little course work in traditional history, literature, philosophy, logic, or the traditional sciences.

Universities and students have plenty of money to continue the weaponization of the university, given their enormous tax-free endowment income. Nearly $2 trillion in government-subsidized student loans are issued without accountability or reasonable demands that they be repaid in timely fashion.

Exceptions and exemptions are the bible of terrified and careerist administrators.

Faced with an epidemic of antisemitism, university administrators now claim they can do little to curb the hatred. But privately they know should the targets of similar hatred be instead Blacks, gays, Latinos, or women, then they would expel the haters in a nanosecond.

What is the ultimate result of once elite campuses giving 70-80 percent of their students As, becoming hotbeds of dangerous antisemitism, and watered-down curricula that cannot turn out educated students?

The Ivy league and their kindred so-called elite campuses may soon go the way of Disney and Bud Light.

They think such a crash in their reputations is impossible given centuries of accustomed stature.

But the erosion is already occurring — and accelerating.

At the present rate, a Stanford law degree, a Harvard political science major, or a Yale social science BA will soon scare off employers and the general public at large.

These certificates will signify not proof of humility, knowledge, and decency, but rather undeserved self-importance, vacuousness, and fanaticism — and all to be avoided rather than courted.

Victor Davis Hanson is a distinguished fellow of the Center for American Greatness. He is a classicist and historian at the Hoover Institution, Stanford University, and the author of “The Second World Wars: How the First Global Conflict Was Fought and Won,” from Basic Books. You can reach him by e-mailing authorvdh@gmail.com.