An American law professor has defended a controversial newspaper article in which she criticised black and Hispanic immigrant ways of life and argued that “not all cultures are equal”.

Outraged students at the elite University of Pennsylvania signed an open letter condemning the op-ed by law faculty Professor Amy Wax and Professor Larry Alexander of the University of San Diego.

In their article, the lecturers called for the reinstatement of 1950s “bourgeois culture” as best suited for “preparing people to be productive in an advanced economy”, arguing that citizens from certain ethnic groups had “abandoned their role as advocates for respectability, civility, and adult values”.

In particular, Profs Wax and Alexander criticised “the anti-‘acting white’ rap culture of inner-city blacks’ and “anti-assimilation ideas gaining ground among some Hispanic immigrants”.

More than 50 students and alumni signed open letters calling on Pennsylvania and San Diego to take action, saying the values espoused in the Philadelphia Inquirer op-ed were “steeped in anti-blackness and white hetero-patriarchal respectability”.

But Prof Wax told The Independent it was the students themselves who were guilty of “incoherence” and that bourgeois values were not “somehow racist”.

“If indeed bourgeois values are so racist, the progressive critics should be out there in the street demonstrating against them, stripping them from their own lives, and forbidding their children to practice them,” she said.

“They should be chanting ‘No more work, more crime, more out of wedlock babies, forget thrift, let’s get high!’ As an added bonus, that would help promote equality.

“After all, giving up their successful habits would soon cause the upper middle class to sink. Of course, there’s little chance we’re going to see anything like that, which shows the incoherence, indeed the silliness, of the critiques.”

The dean of the Pennsylvania law faculty admitted that some students may find the professors’ arguments “disagreeable or offensive”, but said faculty members like students were “entitled to express their views as part of academic freedom”.

“Any assertion that one culture is superior to all others is contrary to our core values and current practices as an institution, and personally and as a scholar of constitutional law and history I reject such a view,” he told The Independent.

“But encouraging broad and robust debate on controversial issues is another core value here, and the right to speak is empty if we only extend it to speech that we like.”

The university’s failure to criticise Professor Wax has only fuelled student anger further. One group describing itself as representative of a multitude of backgrounds at Pennsylvania wrote in an open letter published on Medium: “Penn does not empower all students.

“Instead, by failing to take a public stand against rhetoric that harms, dehumanises, and compromises the education of its vulnerable students, Penn merely reinscribes existing social hierarchies and inequalities. We hold that Penn can do better.”

Speaking to the Times Higher Education website, a spokesperson for San Diego, where the article’s co-author Prof Alexander teaches, said the college had not had any complaints from students, who are yet to return to campus for the new term.

They said: “While we recognise and protect the First Amendment right to freedom of expression, we are mindful that diverse points of view may be upsetting to some who do not agree with opposing perspectives.