Why? Genuinely asking cuz I've never heard of it as a bad thing except in the context of nazis
Discussion
Its used as a way to get citizens to war for far less than they once did. Previously there were hired mercenaries who would wage war. If it looked like they were not going to get paid or lose a battle they would leave.
Nationalism is a clear us vs them. I say this in a very successful bi/trinational peaceful nationstate.
A “nation” is only an abstract idea in our minds, but it has no physical existence. I might have a lot more in common with the guy who lives 200 miles away from me in another “nation” than with the jerk in my neighbourhood. Nevertheless, in nationalism I should rather be on the side of the jerk and, if necessary, fight the other, economically or physically. That should be enough to discard this “idea”.
Go cross the American border to Mexico and tell me it's not a physical manifestation of 2 separate nations
That example is of nation-states. The Irish nation has more people outside of the island of Ireland than inside.
One could say the nation of Christians has no borders, the Bosnians are nationals without a state.
If aliens were watching us from space they would be unable to tell how many “nations” there are because it only exists in our minds. They could say that humans in this area look different than from that area but not why one human belongs to nation A and the other belongs to nation B. Do you know what I mean?
I don't particularly like nationalism either, but this is very broken thinking. The fact that there are exceptions to the rule does not necessarily make the rule invalid.
People born in the same country will no doubt be more similar to each other, on average, than a random selection of people from around the world.
“People born in the same country will no doubt be more similar to each other, on average, than a random selection of people from around the world.”
-> No doubt but that’s because they were socialised differently, not because they are truly different. Nationalism is imposed on them. That doesn’t mean they all truly “belong together” and the guy in the next village doesn’t because he lives behind the border.