Libertarian morality is as follows: According to the principle of homesteading, each man owns his own person, and he therefore owns the things which he produces – those parts of nature hitherto unowned and which, when mixed with his labor, are transformed into productive entities. The only moral ways for these entities to change ownership are voluntary trade and gift-giving.
Those who are productive with their property become responsible for more and more, since they can afford to buy up additional property with their earnings. The overall productivity therefore, will rise.
Figure 1. If only consent was respected in more than sex. Marx's response was that it's not really consensual since the worker is bound to unwanted labour as a means of survival. The libertarian morality of "you still can't force someone to pay you more than your labor is worth" isn't satisfactory to non-libertarians, so see the section on welfare for a discussion of the provision of basic necessities in libertarianism, as well as the one on minimum wage. Either way, there are currently thousands of economic restrictions that are nowhere near essential for survival.