Answer: Libertarianism is the political position that all human relationships should be voluntary, i.e. not subject to the initiation of force by another person. Inasmuch as this is also part of the Objectivist politics, Objectivism is a libertarian philosophy. Not all libertarian thinking is compatible with Objectivism, and some libertarians promote philosophical ideas that would destroy liberty if put into practice, such as skepticism, ethical subjectivism, and anarchism. But the libertarian movement in general is a positive force for political change, one to which Objectivists have valuable moral and epistemological knowledge to contribute and one from which Objectivists can learn about the politics, economics, and history of freedom.
Libertarianism is a position in politics, one that is also known as "classical liberalism," "market liberalism," or, in Europe and Latin America, simply "liberalism." All of these terms derive from "liberty" and signal someone who is a consistent advocate of individual freedom.
A libertarian holds that a proper political order protects its citizens from the initiation of physical force. This means, effectively, protecting a person's rights to life, liberty, and property. As David Boaz of the Cato Institute writes in Libertarianism: a Primer (New York: The Free Press, 1997): "In the libertarian view, all human relationships should be voluntary; the only actions that should be forbidden by law are those that involve the initiation of force against those who have not themselves used force-—actions like murder, rape, robbery, kidnapping, and fraud." (p. 2) Libertarians are thus for freedom of speech and for freedom of contract, or, as Reason magazine puts it, "free minds and free markets."
The principle of non-initiation of force was popularized by Ayn Rand, and it certainly is a key aspect of the Objectivism. To this extent, the Objectivist politics is libertarian. In fact, Ayn Rand's advocacy of individual rights and limited government in her novels and speeches ignited the rebirth of libertarianism in the 1960s, and her thought is still a major influence in the general libertarian movement. However, there are significant differences between the Objectivist politics and the views of many, perhaps most libertarians. Rand herself thought these differences so great that she rejected the label "libertarian." She preferred to be known as a "radical for capitalism."
One important difference is that Objectivism holds that man needs government, a point many libertarians deny. Freedom requires an enforceable system of adjudication that establishes, though objective principles, when force has been used and allows for the rational settlement of disputes on the basis of individual rights to life, liberty, and property. Only an institution that effectively dominates and regulates the use of force in a given geographic area can provide and enforce such a system of law. So we all need government to set us free from force. But many libertarians are anarchists who believe that some "free market" system of competing law courts and for-profit police agencies can ensure a "non-monopolistic" system of rights protection. For a classic exposition of this view, see The Machinery of Freedom by David Friedman (New York: Harper & Row, 1973). For one addressed to Ayn Rand, see Roy Childs, Jr., "Objectivism and the State: An Open Letter to Ayn Rand" pages 145-156 in Liberty Against Power: Essays by Roy A. Childs, Jr., edited by Joan Kennedy Taylor (San Francisco: Fox & Wilkes, 1994).
Against the anarchists, Ayn Rand noted that a free market functions by the free choice of the people involved. As she explained in her essay "The Nature of Government" (in the Virtue of Selfishness), free choices are choices made while free from force. The anarchists want to have their cake and eat it too: it is impossible to have market competition (or even a proper market) for the provision of the protection that frees one from force in the first place. Anarchism, in practice, would amount to civil warfare (VOS 112-113).
But there is a more profound difference between Objectivism and most libertarian views. In some ways, comparing the two is like comparing apples and oranges. Objectivism is a systematic philosophy: it starts with a theory of reality and a theory of knowledge, then develops a moral view using conclusions from the previous two fields, and all those conclusions provide the basis for its politics. Its political conclusions thus stand on a firm and quite specific foundation. Ayn Rand put it this way "I am not primarily an advocate of capitalism, but of egoism; and I am not primarily an advocate of egoism, but of reason. If one recognizes the supremacy of reason and applies it consistently, all the rest follows." ("Introducing Objectivism" The Objectivist Newsletter Vol. 1 No. 8 August, 1962 p. 35.) Taking a systematic approach to political principles is good logic, but it is also of great practical importance. Ultimately, a political position cannot thrive in the culture at large unless it is firmly grounded in a widely accepted philosophic outlook.
Although some call libertarianism a "philosophy," in fact it is just a relatively broad political position. Within politics, there are often significant differences among libertarians: some are anarchists, as we've seen, while some favor a muscular government; and some hold that people have natural rights, while others doubt any rights really exist. Beyond politics, libertarians appeal to a wide variety of philosophical principles. Skeptical libertarians deny the possibility of knowing anything with certainty. Religious libertarians appeal to faith in God for the basis of their beliefs. Utilitarian libertarians, including many economists, hold that economic efficiency, i.e. the good of society, is the standard that justifies economic freedom. Hedonist libertarians argue that freedom is good because it lets you do what you want.
There are libertarians whose fundamental views are deeply inimical to human liberty. This has been a source of friction between Objectivists and the libertarian movement. For example, some libertarians are skeptics about knowledge and morals because they think that any judgment we reach with certainty must be enforced on others. But not so: there is a difference between judging that something is the right thing to do and judging that it is right to force someone to do it. In fact, a skeptic has no reason to be a libertarian, for on his own principles he cannot show that liberty is better than slavery or that the rule of law is superior to despotism. Similarly, when some libertarians support a moral code that promotes altruistic sacrifice to others, they reveal their commitment to ideas that, if taken to their logical conclusions, cannot support liberty in political practice. After all, if our basic moral duty is to serve others, then we should not have any fundamental concern for our own happiness and freedom. Yet this is just what a vigorous defense of liberty requires.
Some libertarians have gone so far as to deny that libertarianism needs a philosophic foundation of any kind. They have held that the principle of non-initiation of force is an "axiom" of social organization that should be accepted on faith, or as self-evident. But political principles are anything but self-evident: they depend on a vast number of conclusions about reality, human nature, and moral action. This is why the United States has not consistently supported the "self-evident" truths of the Declaration of Independence. The rights proclaimed there only have meaning in a richer context of philosophical knowledge. Franklin D. Roosevelt and Thomas Jefferson both supported a right to "the pursuit of happiness," but they were not referring to the same actions or to a similar system of laws in practice.
Libertarians' indifference to philosophy was the primary cause of Rand's refusal to describe herself as "libertarian," and has led many Objectivists to follow suit. Notably, Objectivist writer Peter Schwartz has attacked the libertarian movement as a whole in his essay "Libertarianism: the Perversion of Liberty" (republished in The Voice of Reason). Schwartz accuses libertarians of thorough-going subjectivism and nihilism. However, Schwartz's essay is a polemic, not a responsible piece of cultural analysis. It fails to take note of the serious opposition to radical subjectivism and nihilism on the part of many libertarians. As David Kelley explains in The Contested Legacy of Ayn Rand: Truth and Toleration in Objectivism, prominent libertarian organizations like the Cato Institute and the Reason Foundation, and famous libertarian thinkers such as "Milton Friedman, Ludwig Von Mises, Friedrich von Hayek, Thomas Sowell, and Robert Nozick" are not nihilists (p. 37). Their views are to varying degrees ones that share premises with Objectivism and with which Objectivists may profitably make common cause in the struggle to achieve greater freedom.
There is a proper function for libertarianism as a broad political coalition to promote the institutions of a free society. But without a basis in a culture that prizes objectivity, achievement, and personal happiness, the libertarian cause can never succeed. So libertarians have a genuine need for Objectivism, to provide the philosophical underpinning and analysis required for a solid understanding and defense of human liberty.