WASHINGTON — Opposition to the plans to build a mosque near ground zero, the spot where the World Trade Center's twin towers fell on Sept. 11, 2001, comes in various shades. To their credit, many of the project's opponents have avoided the crass bigotry that is becoming a standard trait of rightwing discourse in the United States.

But even moderate critics of the mosque (actually an Islamic cultural center with a prayer room called Park 51) betray in their arguments two assumptions that are as questionable as they are ingrained in the prevailing public discourse in the United States.

The first of these misbegotten assumptions is to underrate social intolerance as a threat to freedom. While accepting the project's impeccable legal credentials, its opponents nevertheless demand that it be relocated on the grounds that even fully lawful conduct may be offensive to a group of citizens. This is a dangerous road to take in a liberal society.