In particular, what are the differences between nationalism in the 21st century vs 19th century? I've always associated nationalism with the revolutions of the 19th century but with the recent election cycle, I've been seeing the phrase "right wing" or "white" nationalism used in a frequently negative connotation. Has nationalism always carried connotations of racism, xenophobia, etc. or is that a recent phenomenon?
I apologize if any of the questions seem loaded. I'm not intentionally trying to paint the recent wave of nationalism in any positive or negative way.
It's a difficult question because 'nationalism' means different things to different people, and in different time periods. I'd say among much of the general public today (maybe this is limited to the left though) who aren't familiar with the history of nationalism, the word means a vague melange of xenophobia, national chauvinism, excessive patriotism, and sometimes racism. Therefore nationalism in this sense is opposed to many deeply held beliefs among much of the Western political and media classes, such as international cooperation (e.g. the EU, UN, ICC etc.) and ethnic and racial equality. There are of course nationalist movements, like Scottish nationalism, which take great pains to distinguish themselves from that kind of nationalism, but the fact that they feel the need to do this shows what they perceive mainstream opinion on nationalism to be.
I think this mainstream rejection of nationalism comes from two related sources. One is of course Nazi Germany, which did a lot to discredit nationalism throughout the West, and the other is the rise of movements for racial and ethnic equality from the 1960s, so I'd say that it was during this period that nationalism became a 'bad word'.
This shift is reflected in academia, which is of course more precise in defining nationalism. As Hobsbawm says, nationalism wasn't really much theorised about during the age of nationalism from the late 18th to the mid 20th centuries, it was just taken as a given. Hobsbawm writes: "[W]e encounter, in nineteenth-century liberal discourse, a surprising degree of intellectual vagueness. This is due not so much to a failure to think the problem of the nation through, as to the assumption that it did not require to be spelled out, since it was already obvious’" (Hobsbawm 1992: 24). The bulk of the academic work deconstructing and criticising nationalism came from the 1960s onwards, with the work of Gellner, Anderson and Hobsbawm being famous examples.
My reading of this shift is because in the 19th century, nationalism was the 'carrier' of progressive ideas about liberty and equality, opposed to aristocratic domination. Now though, aristocratic domination has been soundly defeated, and international institutions have become the carriers of progressive ideas, and nationalism is seen as 'standing in the way'. These days we are much more sensitive about ethnic and racial equality, and therefore the 'exclusion' inherent in nationalism is seen more problematically today than it would have been during the age of nationalism. E.g. the language of many figures on the left (e.g. Karl Marx talking about savages) would not be acceptable discourse today.