However, there are other theories about what is the most important part of the public interests. Some people say what is important to the public is safety and well-being, and that if free will and property rights aren't providing this then the government needs to assure them. These theories might say that the government should set minimum standards for products and for employee safety, and that if it looks like important business are going to go bankrupt the government should help them so that they can continue to produce for the economy and provide jobs. The public good is defined in terms of job security and quality, and the economic welfare of companies and employees. This theory is in many ways older than free market theory -- even back in the days of the ancient Egyptians, the government set prices for grain and exchange, and subsidized and controlled farmer choices. In other ways, this theory is more modern. Minimum wage laws and other laws protecting employees came into recent existence because business was abusing workers with low wages and unsafe environments. Laws protecting product or service quality also became more common when reformers become upset with poor quality products (such as foods with poison in them, or radioactive alarm clocks, or quack doctors selling snake oil). The problem with trying to manage society in this way is that no government is so all-knowing that it can regulate every aspect of the market without error, and moreover a government which totally protects its citizens from their own choices essentially enslaves them. The benefit with this system, of course, is that it can protect people from their own stupidity and the selfishness of others.

Today, many people talk about how important it is to have a free market where the government doesn't interfere with business; at the same time most of these people do believe that the government should take some steps to protect the public welfare. There is no country today where a truly free market exists, and no country where the market is totally controlled for the good of the people. Deciding which part of the public welfare (whether that be freedom of choice for all or positive outcomes for most) is most important is very difficult, and a personal decision. Most people try to balance these two ideals in order to reach the overall ideal: the true happiness and welfare of society. If you want more information on free market and economic theory, John Kilcullen of Macquarie University has an excellent page about the subject at http://www.humanities.mq.edu.au/Ockham/y67s26.html.

As this complicated first answer has probably shown you, the answer to the second question depends on your personal answer to the first question. I think I have already answered the first part of the question: "How can the free market, driven by greed and financial profits, ever lead to that goal?" The answer is that if all people are equally greedy and profit-oriented, then all people will essentially protect their own financial well-being and so all transactions will be beneficial in some way to both parties or else they would not proceed. If the government does not get involved, self-interest will guide actions to be mutually beneficial for all. The second part of your question, "Why is it good, and when is it appropriate, for government to stay out of the marketplace?" is simple. It is best for the government to stay out of business when the nature of the business relationships in question are such that all parties involved stand to profit in some way (either financially or by receiving products or services they need). For example, Presidential hopeful Kerry suggests allowing market forces