The argument is which is the superior method for making the world better. On one side you have Krugman who believes you should tax the rich and let the government spend the wealth the rich accumulated to improve conditions for everyone.
On the other side you people who think that if you allow people to spend, save and invest their money as they choose, society will come out better in the end.
Side A likes to portray side B as selfish, greedy bastards and side B likes to portray side A as communists thieves. Really though, if you take the actual objectives of both sides I would argue they're generally noble.
There is still the matter of who is actually right. That is where the real argument is.