I am a Libertarian.
The twin sides of the Libertarian coin are freedom and responsibility. It is an individual-based philosophy ("there is no such thing as society" as Margaret Thatcher once famously said), and embraces aspects that are espoused by both the political left and right. I've been accused of being both by different people at different times, depending upon what the subject of conversation is.
In terms of politics, the Libertarian principle is that the only legimate purpose of government is to prevent people harming each other. Thomas Hobbes stated that the basis for human behaviour is self-interest, and thus the natural state of humanity is war, of all against all, in a constant battle to improve our self-interest. Individuals create alliances (tribes, nations, religions etc) in which they make a contract not to harm each other so that they can improve the self-interest of all individuals in the group. In such a group, it is necessary to have a mechanism to enforce this contract, or it is worthless, and in a national grouping, this is known as "the government". In this one purpose, the government should be a powerful government.
So, the government's purpose is to prevent us from harming each other. It is not there to provide health services, or education, or welfare, or give the kiddies a free lunch at school. All of these things are beyond the purpose of government, and should be provided privately by individuals.
The Economy
Adam Smith correctly showed that the best thing a government can do regarding commerce is to get out of the way. Individuals should be free to pursue economic goals without government interference. Markets should be free, which simply means that people should have the freedom to sell their goods and services to each other at a price agreed upon by the parties to the transaction, no matter where they are located. Going with this is responsibility: people have the responsibility to provide for themselves economically, they have no right to expect others to support them, nor should they be expected to support others.
Corporations have no social purposes. A corporations only purpose is economic, and that purpose is to make money for its owners. All corporations have this one and only purpose. They accomplish this purpose using different methods (selling goods and services) and using different tools (machinery, employees etc). If the corporation is no longer fulfilling its only purpose, there is no longer any reason for the continued existence of that corporation. There should be no goverment assistance to corporations, for this merely perpetuates inefficiency and stagnation. Nor should there be any protectionist tarriffs or duties placed upon movement of goods and services in order to give certain companies a buffer from free competition. This also stifles innovation and advancement, and has a net negative effect upon the economy.
This also means that any taxation beyond the absolute minimum necessary to enable the government to fulfill its one purpose is wrong. Particularly egregious is the mechanism of graded income taxation, since this taxes success and the people who create it. A more Libertarian form of taxation would be a head tax, where each person contributes the minimum necessary to enable the government to stop us harming each other. All other taxation is an injustice and an infringement upon individual freedoms.
Social
Socially, people should be free to makes their own decisions, but they also have the responsibility to accept the consequences of their decisions. For example: drugs. Under Libertarianism, people are entirely free to decide whether or not to use any particular drugs. It is not the governments job to dictate to them. All drug use should be free and legal. This is the freedom side of the coin.
The responsibility side of the coin is that a person must accept the consequences of making poor decisions regarding drugs. It is not the governments purpose to provide rehabilitation centres or programmes funded by taxes.
Person A should be free to take drugs, if he so chooses. But persons B, C, and D should also be free of coercion through taxation to subsidise the poor decisions of person A.
These two sides of the coin, freedom and responsibility, are the Libertarian approach to virtually any social question.
The Libertarian Meritocracy
One of the strengths of Libertarianism is that when people are free to make their own decisions and pursue their own economic self-interest without government interference, a meritocracy is created. To put it bluntly: a meritocracy seperates the intelligent and the industrious from the lazy and the stupid. The former succeed, the latter fail. But because the basis of human behaviour is self-interest, far more people will try to improve their circumstances than otherwise, particularly if they know that other people will not be coerced through taxation into supporting their unproductive existence.
A meritocracy is natural selection at work, and thinking that the human animal is not subject to natural selection like any other animal is an emotional delusion.
This also answers questions like "should the US get more involved internationally". The purpose of the US government is the same as every other government: to prevent people harming each other. If another government harms people, then it should be removed, by force if necessary. This is why I, as a Libertarian, supported the Iraq war. (To be fair here, Libertarians were split on this issue. Quite a lot of them felt that this was not a justification for the Iraq war. I obviously do.)
The environment? Firstly, let the market operate. Individual consumers will become more concerned the further the environment deteriorates. Corporations that do not respond to consumer concerns over the environment will not survive economically. Those that do will have a strategic edge. Environmentalism will benefit accordingly. In clear cut cases of individuals or corporations harming others through environmental degradation, the government can fulfill its purpose. It's not a co-incidence that in nations where the government hugely oversteps its legitimate purposes and takes over and runs industry, environmental pollution is horrendous.
Objection?
Logansrun raised the most common objection: Libertarianism taken to its logical conclusion is heartless.
My response? Tough. Utopia is not an option. Everything reduces to numbers. The system which benefits the greatest number of individuals is the superior system. In analysing systems, emotional reaction fogs the clarity of rationality.
Expatbrit