Why are we so bad at predicting major political events?

What is going on now in the Mideast is a good example. I will not venture to guess what direction it is heading in or how extensive the changes will be, but it is clear that something major is happening. How come nobody saw it coming?

Few people predicted the worldwide recession and I don’t think anyone knew the extent to which the Soviet empire would collapse. Those who saw WW I as the war to end all wars were quite a bit off the mark.

Are these events inherently unpredictable? Are things just too complex?