Roderick Stackelberg once said "The more a person deems absolute equality among all people to be a desirable condition, the further to the left he or she will be on the ideological spectrum. The more a person considers inequality to be unavoidable or even desirable, the further to the right he or she will be."
When I first came across this quote, I was delighted. It summarized my own thoughts on this subject perfectly. The implications are deep, and I want to explore them further here.
Suppose that you had many cloned lab mice in a cage. You discover that all the mice start out identical, but tend to diverge over time. Some are starving, others are getting fat. They're all being kept in the same cage, so you begin to investigate why this happens. You notice that the starving mice are separated from their food by a pool of water in the middle of the cage. To fix this imbalance, you drain the pool.
Suppose you also have another cage, this time filled with wild mice. You begin to see the same imbalance that you saw among the cloned mice, but this time, you are unable to find an obvious explanation for it, since ALL of the mice in this cage are separated from their food by water. You find that some of the thin mice haven't searched for the food dispensers. Others seem aware of them, but give up without trying, because learning to swim is too hard. Yet others just don't feel it's worth it, and would rather starve. Since these mice have all made choices, you choose to not intervene.
The cage of cloned mice is the pure left wing model of the world. Differences are always artificially induced, and thus entirely avoidable.
The cage of wild mice is the pure right wing model of the world. Differences are always natural, and are thus entirely unavoidable.
I'm not saying that either of these cages are real, but they represent the core of many people's world views. In the cloned cage, leaving the mice to their own devices seems cruel and heartless. In the wild cage, it seems entirely fair.
Reaching any sort of political consensus requires agreeing on which cage is going to serve as the model of reality. This is impossible, since switching the cage switches which side of the argument you are on in the first place.
Personally, I believe in a synthesis of these world views. I'm one of those annoying centrists that everyone seems to hate. ;-)