I mean over all, people are getting more and more Liberal as we speak. Once the older generation dies off, then the Liberal revolution will really have taken its toll on conservatism. Also I am talking more about Social conservatism, not a bunch of Libertarians.
The fittest survive and the rest will have to figure it out. It's just like being an animal out in nature, you have to survive on your own after you've been raised by your parents. However, there should be plenty of private charities to help out people in poverty or need that extra boost.
Even if you accept the whole Darwinian ethos, that's a false comparison. Animals basically depend on their genetic ressources. Human society allows people to inherit trustfunds and family land etc., which makes the idea of "survival of the fittest" ridiculous. Some highly able individuals never get a chance because of their poor social background. While a lot of morons survive for generations based on the abilities, privileges and luck of their ancestors.
