Scholars generally seek to come up and prove counter-intuitive arguments. They are sexier, more attention-grabbing and thwart the usual "so what" question. So, I have enjoyed the past few years the idea that xenophobia has positive qualities, particularly that fear/intolerance of others may serve as a break on irredentism (expanding one's country to include territory inhabited by lost kin). A pretty jazzy counter-intuitive argument, as far as political science kind of arguments can be thought of as jazzy.
Events in Oslo remind me that xenophobia is usually seen as negative because hate is inherently bad and leads to bad outcomes. We know very little about this guy, Anders Behring Breivik, who killed so many, but it does seem to be the case that his personal ideology was one of xenophobia--hating the immigrants coming to Norway and hating Norway for tolerating these foreign folks. Yes, one can have anti-immigration positions and not choose to kill lots of people, so it probably has a lot more to do with his personal dysfunction than with the "cause" of hating foreigners. We should not paint all xenophobes with the same brush, as many can just protest and organize politically.
Still, hate is hate, and those who preach hate usually end up either preaching violence or creating an environment where violence seems to be a solution. I tweeted about Oklahoma City when I first heard of the attack, as I was flying back from Australia and got the news and internet connections intermittently. I thought of OK City mostly because I screwed up early that day, leading class discussions about it (it was my second year of teaching) and basically assuming it was done by Muslims. Timothy McVeigh taught me a lesson that day--not to jump too quickly to conclusions.
I do think that McVeigh may have more to teach us about this new event--about the combination of unbalanced loner and a movement to hate others. There has been a steady rise of anti-immigration and anti-Muslim political movements in Europe (and elsewhere). This event may have a positive impact in that it may break the momentum, as the radical right fell apart in the US at least for a time after OK city. At least, I have to hope so.
In some ways, this event reminds me more of Columbine than anything else. That there is a violence outbidding process where each crazed individual must up the stakes to get attention. Suicide is not enough, killing a few co-workers is not enough, a small bomb is not enough, a shooting spree has been done, so the acts become larger and larger. I am afraid that we will see more damage done by damaged individuals. The technology of self/other destruction continues to "improve" so that the next guy will do even more harm.
Coming back to the Saideman and Ayres book, I should note that we recognize that xenophobia's positive possibilities (deterring aggression) traded off of the negative (domestic discrimination against out-groups). So, in the Norwegian case, there is no irredentism to be deterred, so xenophobia only has the normal, intuitive, negative consequences that we have long understood.
Depressing non-counter-intuitive thoughts on a hot summer's weekend. Time to go to the movies.