Libertarianism is about the most basic pragmatic view of life. There simply isn't enough variance in human intelligence for a few people at the top to be able to make effective decisions for everyone else.
Libertarians believe in three basic rights - life, liberty, and property. All government should do only/everything necessary to preserve those rights. It follows then, that Libertarians are strongly against regulation unless it is absolutely necessary (as this leads to corruption, monopolies, etc).
From the perspective of environmental issues, the government is not doing ENOUGH to protect people from corporations that violently destroy citizen's rights to life and property. The corporations do not own the air in the sky, they don't have a right to pollute the river you drink from, and they certainly don't have a right to cause you to be diseased by Mercury poisoning.
On the other hand, there /is/ enough variance in human intelligence (or at least human capability) for huge disparities in wealth even in social democratic societies. How much more pronounced must this difference be in a libertarian society?
Libertarianism is all about distributing power, instead of consolidating in. This results in less violations of individual liberty (you don't have governments stealing from the poor and giving to the rich, or corporations polluting the land the poorer live on, or large media conglomerates effectively brainwashing people into submission). This results in mostly and increase in prosperity for the poorer folks, while the rich of the rich might not be able to sustain their position (although there will still be rich people).
I admire the desired outcome (and that of Shimrod in a different reply), but I'm skeptical because of the history of inequality that capitalism has manifested, which has only increased with the liberalisation of markets.
It may be possible to successfully argue, as you and Shimrod do, that inequality is, in significant part, because of rather than in spite of the government. I'd rather like to see such an argument. As I understand it the classic libertarian arguments have focused on increasing production and efficiency rather than decreasing inequality.
(NB decreased inequality is a very different thing from decreased poverty)
Please show me this capitalist country so I can move there.
It is true, Libertarianism does not focus on decreasing inequality - at least not in the sense of absolute privilege, because it is a meritocracy - Libertarianism does, however, focus on decreasing inequality of opportunity. If you decide to slack off like the cricket during the summer - your fault. But you learn, that maybe next time you should work, instead of getting bailed out and then noone has incentive to ever do any real work. This is why communism failed.
The truth is, that if you want people to not go hungry, and live prosperously, the only way to do that is to craft the game, such that the Nash equilibrium is beneficial, rather than harmful.
And yes, there are some people incapable of taking care of themselves - they might be handicapped, or get in a car accident - however, in a society of prosperity and freedom, people will have enough extra, and not be afraid of everyone trying to steal what they have, that charity will increase. So, first, you decrease the poor population to a size that is pretty much as small as theoretically possible, and then those people are taken care of by the abundance of all others. I mean, if you had $1million dollars, and you didn't have the government trying to take it all the time, would you really pass up helping out those in need?
The reality is, that there will always be poor people, and history has shown that socialism certainly does not solve that problem (the more socialist countries have more poor people). If you claim the US is a capitalist system, well it might be compared to some other countries, but then again, we are more prosperous compared to those countries as well.
From the perspective of environmental issues, the government is not doing ENOUGH to protect people from corporations that violently destroy citizen's rights to life and property. The corporations do not own the air in the sky, they don't have a right to pollute the river you drink from, and they certainly don't have a right to cause you to be diseased by Mercury poisoning.