Not all libertarians are explicit anarchists. But all libertarians who are part of the libertarian movement of today, are at least _implicit_ anarchists. Why? The answer lies in the very nature of the libertarian movement. The reason the the libertarian movement started back in early 1970s was to make all kinds of people join a common cause for “freedom”.
Now while this might, at a first glance, seem like a good idea, it in fact is not a good idea at all. Why? It doesn’t matter, according to libertarianism, whether you ground your defense for freedom on a rational philosophy or on an irrational philosophy. This indifference implies that libertarianism view philosophy as ultimately irrelevant to the issue of freedom. Apparently, “freedom” is compatible with every kind of philosophy (Platonism, Christianity, Kantianism, Hegelism, etc) and, by the very same logic, the libertarians usually claim that libertarianism is compatible with every code of morality (Hedonism, Utilitarianism, Altruism, etc).
This is precisely why you can find both the friends of capitalism and the enemies of capitalism, that is the anarchists, within the same alleged movement for “freedom”. This is why you can find both better people such as Ludwig von Mises or Henry Hazlitt and worse people such as Walter Block and Murray Rothbard in the libertarian movement.
What does the fact that the libertarian movement view essentially every philosophy or code of morality as being coherent with libertarianism and “freedom”? Well, for one thing it implies that every idea is equally true or false. How else would you explain the total indifference? And by the same logic every code of morality is equally true or false. This is _subjectivism_!
What does subjectivism imply regarding the case for freedom? Well, if there’s no objective knowledge, no objective concepts, no objective set of values, then there’s no objective ground for restraining peoples freedom of action in any regard whatsoever. If so, then there’s (rationally) no legitimate ground for a government.
Thus the anarchists within libertarianism can always say in answer to those who want a limited government: “Who are you to say that there should be a government that forbids certain kinds of actions simply because you seem to think they consistute ‘force’? Who are you to define ‘force’?”
If truth, concepts, values is subjective then anarchism is the only consistent alternative within the libertarian movement. This means that “freedom” according to libertarianism means that: the individual should be free do to whatever he feels like - _without any restrictions or restrains of any kind_.
Further, if every philosophical defense for freedom is equally true or false, then this implies that freedom doesn’t have or need any intellectual or rational defense. If that’s the case, then it can ultimately only mean one thing, namely that the libertarian movement rest on the premise that freedom is good merely because the libertarians _feels_ it. (It is worth mentioning in this context that leading libertarians such as Walter Block often define libertarianism as simply “the non-aggression _axiom_”.) Subjectivism is indeed an integral part of the libertarian movement.
This is why it’s perfectly all right to say the the true _essence_ of the libertarian _movement_ is nihilism, subjectivism, amoralism and anarchism. This is also why it’s perfectly in order to say that (the better) libertarians who don’t agree with this assessment in fact fail to see the true essence of the libertarian movement just like some communists and environmentalists fail to see the true essence of their movements.
For further details on this subject read Peter Schwartz pamphlet _Libertarianism: The Perversion of Liberty_ . You can buy it at the Ayn Rand Bookstore.