What a bunch of horse shit answers. I want some ****ing paragraphs.
When I was in college I wrote a small 3-5 page piece on this very question as an assignment. To this day, if I could go back and redo one paper from all my time in college, this would be the one. Hands down, no question at all.
In the paper I wrote that I more or less took the opinion stated above by syskatine, "not really, until it is" while also stating my opinion of the good that can arise from nationalism. I believe the error in my thought process at the time arose from a misunderstanding and conflation of nationalism and patriotism. I believed that the existence of one was dependent upon the existence of the other. Namely, that patriotism was born from the existence of nationalism. I had assumed that for an individual to be a patriot one must have a love of their government as it either currently exists or had been established.
Since that time I have defined what I believe is the definition of each. Patriotism is defined by one having a natural love of the geographic region in which he lives, the culture he is a part of, and the people that compose the society in which he belongs. It is required for a society to maintain it's freedom, prosper as a society, and improve as a species.
Nationalism is defined as an unhealthy love of one's government which becomes destructive. This love of one's government is almost always accompanied by a thirst for expanding said government to those not fortunate enough to dwell beneath it. The attempt to spread this wonderful creation inevitably results in the loss of innocent lives on both sides, destruction of cultures, cities, resources, and the eventual fall of the nation state itself. Campaigns of propaganda are utilized to gain support for the empire building that ensues. The nationalism is falsely presented as patriotism, moral arguments for aggression are made, and the "enemy" is dehumanized. The government evolves into the final authority on morality replacing entire belief systems, society begins to deteriorate, and an avenue for others to impose their will on others through use of force is championed as "progress." With the latter being morally reprehensible on its own.
Is that the kind of thing that suits your fancy sir?