Since the terrorism on Sept. 11 that shocked our nation, verbal and physical attacks against persons of Arab descent or Islamic faith have been reported in Maine and many other states. If one goal of terrorism is to destroy a society’s social and moral fabric, these attacks indicate that the plane hijackings have had an ugly impact beyond the thousands of lives tragically lost.

Studies in sociology and social psychology tell us that prejudice increases when times are bad. Frustrated by economic downturns or worried over war and other political conflict, people often lash out at certain racial or ethnic groups blamed for these problems. Although our flag stands for democracy and tolerance among other values, our nation’s history is in fact filled with prejudice against groups unfairly scapegoated for economic and political problems.

Examples of such prejudice abound. For example, as U.S. cities grew rapidly before the Civil War, African-Americans and Irish immigrants living in many Northern cities were attacked by mobs that blamed them for urban problems. The Mexican War that began in 1846 fueled prejudice against Americans of Mexican background. During the 1870s, mobs of whites assaulted Chinese immigrants who, they feared, were taking away jobs for whites. In the early 1900s, lynchings of blacks in the South increased when the economy worsened and decreased when the economy improved.

A few decades later, prejudice against Japanese-Americans increased after Japan bombed Pearl Harbor in December 1941. Many came under physical or verbal attack, and eventually the U.S. government confined more than 100,000 Japanese-Americans in internment camps. Popular at the time, this internment is now regarded by many as a shameful act of prejudice. Tellingly, the government did not put German-Americans into internment camps, even though the nation was also at war with Germany.

The U.S. historical record, then, shows that prejudice increases during times of economic and political conflict. The recent attacks against persons of Arab descent or Islamic faith in Maine and elsewhere repeat this sad pattern. By betraying the values embodied in the flags now flying across America, they give Sept. 11’s terrorism an early victory.

In the days and weeks ahead, Americans of all faiths and backgrounds must speak out for tolerance and against hatred. U.S. history is filled with acts of prejudice, but it is also filled with acts of kindness. To honor the thousands of people who died on Sept. 11, we must, at the very least, affirm that the recent acts of prejudice have no place in a nation that professes “liberty and justice for all.”

Steven Barkan is a professor of sociology at the University of Maine.