Suppose there are two main political Parties that alternate back and forth in power. Let's suppose one of them wants the levels of something at 2000 and the other wants the levels of that thing at 4000. (It could be budget deficit spending, immigration, etc) Well, when one Party gets into power, they're going to try to amplify the increase/decrease even beyond the level they think is optimal, to try to compensate for the years when the other party was in power. So instead of having a period of 2000, followed by a period of 4000, there's more likely going to be a period of 1000 followed by a period of 5000. This is phenomena is going to increase the instability of government policy. With the two side effectively waging a "war" on each other, trying to go to further extremes when they get into power, to attempt to undo the policies of the other.