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.”
Let’s be clear: If the second paragraph is the only definition of nationalism, nationalism is always a bad thing. Furthermore, I acknowledge that this definition is what some people have in mind when they call themselves nationalists.
At the same time, even anti-nationalists would have to acknowledge that if the first paragraph is the definition of “nationalism,” nationalism can often be a beautiful thing.
Nationalism is beautiful when it involves commitment to an essentially decent nation and when it welcomes other people’s commitment to their nations. Nationalism is evil when it is used to celebrate an evil regime, when it celebrates a nation as inherently superior to all others and when it denigrates all other national commitments.