Presidential candidate Donald Trump called on Monday for a ban on all Muslims entering the US. He has previously called for surveillance against mosques and a database for all Muslims living the US. Below, some US scholars respond.

Sahar Aziz is an associate professor of law at Texas A&M. She is author of Sticks and Stones, the Words That Hurt: Entrenched Stereotypes Eight Years after 9/11.

Trump’s desire to keep Muslims out of America goes back two centuries. The Naturalization Act of 1790 barred Muslims from citizenship because only white people were eligible. Muslims were viewed as either black slaves, who were not considered full persons, or Turks and Arabs who were deemed enemies of white Christianity – a hallmark of American citizenship.

Even after the end of slavery, Muslims continued to be excluded. Immigration laws in the late 19th and early 20th centuries sought to exclude Chinese, Japanese and other Asians. Whiteness was still the prerequisite for naturalized citizenship. Islam was associated with Asiatic cultures deemed antithetical to American values.

What makes the contemporary period different is the exclusive focus on Islam and Muslims as the primary threat to American life – as opposed to Muslims being caught up in anti-black or anti-Asian prejudice. Mirroring the historic racist rhetoric against the Chinese and Japanese, a critical mass of Americans view Muslims as disloyal, suspicious, dangerous and possessing a culture deemed irreconcilable with American norms.

We witnessed the manifestation of such stereotypes most acutely in the months and years immediately following the terrorist attacks on 9/11. Individuals identified as Muslim – either by their headscarves, names, national origins or associations – were assaulted, spied on, investigated or subjected to “special registration” procedures. However, the post-9/11 discrimination is not merely backlash, but rather an entrenched form of bigotry.

At a time when most Americans are taught that our nation is post-racial and that we have moved beyond Japanese internment or Chinese exclusion laws, Trump’s statements and consequent rise in the pollsremind us that our nation has not advanced as much as we’d like to believe.

Muniba Saleem is assistant professor of communication studies and a faculty associate at the Institute of Social Research, University of Michigan. She is the author of Exposure to Muslims in Media and Support for Public Policies Harming Muslims.

Trump’s statement is, of course, unconstitutional and un-American.

Unfortunately, research suggests that average Americans who are exposed to negative media images of Muslims are likely to support such civil restrictions for Muslims, even if they are US citizens. Research further reveals that most non-Muslim Americans do not have personal interactions with Muslims. Research published in 2009 suggestsAmericans rely on media as their primary source of information about Muslims, which largely depicts Muslims in a negative light. Media stereotypes are especially likely to influence negative attitudes toward depicted groups when people have little real-world contact.

Denise Spellberg is professor of History and Middle Eastern Studies at the University of Texas in Austin. She is the author of Thomas Jefferson’s Qur’an: Islam and the Founders.

Nothing about Trump’s vilification of an entire American religious minority is unique. Trump’s tactics are borrowed directly from a script provided by Frank Gaffney, a known Islamophobe. Gaffney has been condemned by both the Anti-Defamation League and the Southern Poverty Law Center. Trump referenced Gaffney in his speech suggesting the US bar all Muslim immigration. He cited a poll with no verifiable results conducted by Gaffney’s organization, The Center for Security Policy.

The poll, designed to sow fear, asserted a massive untruth: “25 percent of American Muslims agreed that violence against Americans here in the United States is justified as a part of global jihad.” The Pew Research Center and Georgetown University debunked these claims, but the inflammatory impact lingers.

In 2010, Gaffney’s center published “Shariah: The Threat to America,” a right-wing manifesto that became popular among the Tea Party as the blueprint for nationwide anti-Sharia law bills in numerous states.

In 2008, Gaffney insisted that President Obama was born in Kenya. He said Obama “might secretly be Muslim.” Trump was a strong anti-Obama birther proponent. His birtherism extends naturally into his Islamophobia, aided by so-called “experts” whose dangerous goal it is to persuade Americans that all Muslims are the enemy within.

This baseless, fringe untruth first took on currency in the 2012 presidential election cycle, when Herman Cain suggested Muslims submit to loyalty oaths before they could serve in the US government. He forgot to read the no religious test clause of the US Constitution, Article VI, section 3.

Trump’s attacks are a predictable universalization of Gaffney’s ideas. Rather than attack individual Muslims, Trump has extended the premise. He sees all Muslims as threats.

Trump’s dangerous assumption is that American Muslims are not American and certainly not citizens. Casting this group as un- or anti-American is un-American and unconstitutional, as Muniba states. But the roots of Trump’s bigotry do have a definite ideological source origin.

Eli Clifton relates in Foreign Policy that Gaffney’s organization is well-funded – receiving $US3.55 million in 2013 and $2.04 million last year. Christopher Bail offers an excellent sociological study on how this fringe group, with no expertise in Islam as a faith or academic understanding of American Muslims as citizens, moved to the mainstream.

The message resonant with Gaffney, and now Trump, to the American electorate already filled with anxiety after the attacks in Paris, then San Bernadino: “Be afraid, be very afraid.”

Sahar Aziz is an Associate Professor of Law, Texas A&M University, Denise Spellberg is a Professor of History and Middle Eastern Studies, University of Texas at Austin and Muniba Saleem is a Assistant Professor of Communication Studies, University of Michigan. This is a an extract from an article published on The Conversation on 11 December. It is republished with permission.