From socialism to nationalism, debunked ideologies are making a return.

The defeat of measles in the United States was one of the great good news stories of the turn of the millennium. Prior to 1963, when a vaccine was developed, the highly contagious virus led each year to 48,000 hospitalizations and 400–500 deaths, mostly among small children, according to the Centers for Disease Control and Prevention (CDC). But immunization campaigns steadily eroded the disease's reach, and by 2000 it was declared eliminated from American shores.

In order to make arguments for nationalism, we have to define it.

The first definition in Merriam-Webster is "loyalty and devotion to a nation." But in a second paragraph, it adds, "especially: a sense of national consciousness exalting one nation above all others and placing primary emphasis on promotion of its culture and interests as opposed to those of other nations or supranational groups."

On Sunday, French President Emmanuel Macron spoke at a ceremony marking the 100th anniversary of the end of World War I. There, he took the opportunity to slam President Trump's "America First" nationalism. "Patriotism," Macron said, "is the exact opposite of nationalism: Nationalism is a betrayal of patriotism. By putting our interests first, with no regard for others, we erase the very thing that a nation holds dearest, and the thing that keeps it alive: its moral values."

President Donald Trump and dozens of world leaders gathered Sunday in Paris to mark the 100 years since the moment World War I ended.

Is a nationalist simply the opposite of a globalist? Our reporter looks at the term’s various meanings, and what President Trump may be communicating when he uses it.

The president, of all people, knows the dark connotations of this word.

President Trump said Tuesday he’s a proud “nationalist” for American superiority and rejected a reporter’s suggestion that the word is a sneaky signal to white supremacists.

Trump’s supporters backed a time-honored American political tradition, disavowing racism while promising to enact a broad agenda of discrimination.

Understanding the historic tension between America as an idea and America as a folk-group can help us strike the right balance between nationalism and idealism.

Trump’s victory should usher in policies rooted in patriotic assimilation and the national interest.