I see many libertarian-leaning Conservatives arguing in the following way:

1. Humans are selfish by nature.

2. For society to work, people need to contribute to each other.

3. Therefore we need to construct a society where the selfishness of individuals benefit one another.

So, selfishness basically leads to altruism, given that all people have an equal opportunity of making such contributions. There are a few problems with this line of arguments. #1 can be questioned, now that we better understand the evolutionary function behind altruism. So can #3; does self-investment always result in collective benefits?

The real virus in libertarianism is tragedy of the commons, or the idea that positive action taken by individuals alone may harvest negative consequences for the group as a whole. The environmental problems we face today are a good example of that. Sure, it's good to expand the economy and produce new goods and services, especially for individuals who want to secure a good standard of living. But the altruism only works within that human system, or market, if you will. What lies outside of it? Added together: water pollution, toxic air, extinct species, dying forests and urban sprawl. Chaos.

Libertarians always dodge the green issues, so do most Conservatives, because they only recognize the internal system: the economic market. They don't realize the long-term consequences of our lifestyle, which of course will impact the internal system as well. Therefore this line of thinking, I argue, is not long-term viable, because similar to the welfare State, it assumes we can endlessly consume resources without the system itself ever being effected by the consequences of that consumption. Margaret Thatcher famously said that "the problem with socialism is that eventually you run out of other people's money" - today we know this is just as true about our environment.