Why has the myth persisted that Republicans are more fiscally responsible than Democrats? Why do we still tell our children Santa exists?
Because we like it that way, pure and simple. Of course, the Santa myth is really tough on dirt-poor families at Christmas time. The myth that Republicans are the party of the fiscally responsible has had god-awful repercussions for the increasingly impoverished American working and middle classes.
But there you go: we're idiots. If you'd like a way out of your state of political delusion, Paul Krugman can help.