Doesn't Extropianism already avoid the term libertarianism in favor of the term "self-ownership"? That's how I remember it from a couple years ago. But, here's a bit of defense of libertarianism.....the Rothbardian anarcho-capitalist kind based on self-ownership:
{Responding in general terms to the 2 essays}
http://www.cs.bham.ac.uk/~jah/politics/libcrit.short http://www.etsu.edu/philos/faculty/hugh/libertar.htm
Libertarians define liberty as the ability to take any action except those which involve initiating force against others. "Initiating force" does just not mean "using force", but means agression, that is, using force not as retaliation or defense, but as exploitation, ie, for violating the self-ownership of others. I think Herbert Spencer referred to this as the principle of "equal liberty", not an invention of modern libertarians or Randists......libertarianism has nothing to do with "minimizing coercion" or "maximizing liberty" in the sense of "doing what one pleases". As we all know, very significant, even BRUTAL coercion is required to maintain one's self-ownership and the ownership of legitimately acquired and produced property. Yes, this is why the individual or family or legitimate business might need to own machine guns or cannons or death rays. Weapons of mass destruction, on the other hand, would have no valid libertarian use.
And yes, agression can only be defined in the context of valid property rights. However, possession is 9/10 of property law. Unless, you can get a consensus from your neighbors and/or private protection agencies that someone's holdings are illegitimate, their possessions will be accepted as legitimate property. You will have severe difficulties if you try to use force to re-possess property based on your personal opinion alone. However, there would be no prior restraint of such actions under anarcho-capitalism! This in itself would be a factor in the commonly accepted definition of legitimate property in an anarcho-capitalist society. There might be a greater emphasis on protection and defense.
Yes, only anarcho-capitalist libertarianism is consistent libertarianism. Copyrights and patents are not libertarian and any minimal state violates violates libertarianism by definition. Copyrights might be libertarian if they were truly voluntary, that is, the purchaser of a book signed a contract agreeing not to reveal the contents of a book and agreed to only sell the book to those who similarly agree....not a likely scenario. People might agree not to reveal contents of a book for a certain number of months so as to give the author's publisher a headstart?
Police and court systems provided by a minarchist state are socialist and unjust from a libertarian perspective. Police protection and courts for those who do not contract for such would be charity in an anarcho-capitalist society. In this, a minarchist state should be considered a welfare state.
Libertarianism leads to conclusions you disagree with? So what? Libertarianism is what it is.
Why are {you} so adamant in desiring re-distribution? Your fear that someone will be without means, charity, or opportunity in the absence of the State is quite misplaced. A detailed analysis shows that such dire circumstances generally occur because of State, or more properly, the ruling class that uses the State as its instrument.