1. Libertarianism holds no righteous values--it is inherently immoral. In its theory, it has no purpose besides facilitation of self-indulgence. The Libertarian Party itself, for instance, is simply a "big drug party," denying any obligations of people to follow any objective standards for behavior.
2. Libertarianism has no security--it cannot head off a danger. Government actions can only deal with dangers which have already struck. It cannot fight the terrorist threat, since it precludes foreign wars, allows actions at our border only after a threat becomes imminent (that is, after it's too late), and prohibits domestic/homeland security. No assertive action with regard to people or property can be taken to deal with impending natural disasters, and even after they hit, a libertarian regime's options are very limited. Irresponsible individual actions can only be stopped and/or punished after they cause death, injury or damage. Libertarianism denies the social and societal damage done by many so-called "victimless crimes," due to its fixation on the individual. In fact, a libertarian cannot in good consistency be a commissioned law enforcement official, as such a position requires upholding the federal and state constitutions (which libertarians largely abhor for their giving of statutory authority to a government) and enforcing of arbitrary laws even when no (obvious, in their view) harm is done.
3. Libertarianism is inherently non-(un?-)patriotic--it has no loyalty. Whereas the individual is held to be of higher rank than any community, there is no natural duty to one's country. Hence there is no call for patriotism. In Randist libertarianism especially, the very concept of individual sacrifice is considered evil, thus precluding even patriotism by choice. Thus, the whole idea of standing for one's country, people, etc., is anathema to libertarianism.
4. Libertarianism facilitates the worst of humanity--it destroys a society's ability to be good. Under the influence of a regime that denounces not specific values or restraints, but in fact the very concept of values and restraints. Ultimately, the people themselves--certainly in the second generation--would throw off all personal restraint, regardless of upbringing, ending any element of America meeting John Adams' "moral and religious people" standard for the suitability of our Constitution (not that libertarians like the Constitution).
5. Libertarianism is ultimately atheistic--like communism, it cannot handle the idea of a God or higher principle. To accept the idea of a God or higher principle would lead the righteous individual to push--properly, realistically, and constitutionally--for the reflection of their values in government policies. Libertarianism rejects any community reflection of specific values. Thus, libertarians cannot also be Christians (Romans 13), Jews (Genesis 9), or frankly any spirituality, nor can they also truly be patriots (see Point 3).
6. Libertarianism inherently requires violation of its principles--it is a farce. A libertarian regime will be forced to depart from its principles in very explicit ways. Without a meaningful or usable military, it will be forced to rely on even more covert operations than previous administrations, despite their conspiracy-theorizing condemnations of any foreign military action. Without legal means to deal with internal dissent, it will be forced to engage in extreme "secret policing" of the populace, despite their conspiracy-theorizing condemnations of the relatively benign Patriot Act.
7. (Regarding its constituents) Libertarianism is heavily disingenuous--it is a facade. Present-day, the libertarian movement consists heavily of people who are far from libertarian. A disproportionate number--probably a majority--of the movement are White nationalists whose actual positions are rather authoritarian. They use libertarianism as a cover because it offers a non-racial way of publicly opposing Affirmative Action, etc. In truth, they often favor dictatorial governance and control of speech. Though one might call them, "pseudo-libertarians," they are still a strong driving force of the movement. [NOTE: Ron Paul seems to attempt to bridge the gap between actual, or "paleo-"libertarians and pseudo-libertarians by embracing the pseudos racial philosophy and ZOG views, while holding the paleo views on drugs and laws in general.] Say what you will, good or bad, about their aims, they are still disingenuous.
Ultimately, libertarianism is untenable--it cannot survive. The result of libertarianism's traits, including those outlined above, is to break down any social structure or strength. Traditions are left at the mercy of Leftist agitators. Military strength is evisorated. Foreign allies, be they allied states or individuals, are alienated--screwed over. Intelligence efforts are essentially non-existent. Covert operations are precluded, and if launched would require extreme efforts to keep secret (in other words, the operatives sent would likely have to killed to maintain their silence), and if discovered would COMPLETELY discredit both the libertarian administration and the country. (Not that covert operations would have much chance of tactical success, given the evisoration of conventional military assets, preclusions on deploying conventional forces out of sight of the homeland, and the loss of all foreign allies.) The people ultimately lose any sense of responsibility, and thus the society which ironically was what in a practical sense facilitated the libertarian indulgence collapses, leading one way or another in the loss of that "liberty." Ironically, the chaos and destruction caused by libertarianism would likely create an overwhelming popular political pressure to depart of it in favor of a decidedly NON-libertarian system that allows for heading off dangerous situations or behaviors.
Hence, libertarianism may in fact constitute literally the worst possible philosophy of government and society. It has all the righteousness of libertinism. It has all the loyalty of the Left. It has all the inherent responsiveness to the people of most fascist regimes. It has all the compassion of Ayn Randism. It has all the group identity of present-day conservatism. It has all the realistic chances of success of Communism. It has all the law and order of liberal/Left civil libertarianism. It has, among many of its constituents, all the racial tolerance of Nazism. And it has all the values beyond materialism of most of the Tea Party movement. Whatever good can be said of it will be lost in its second generation (if a libertarian country by some miracle lasts that long), thus contradicting the Constitution's preambular aspiration of "secur[ing] the blessings of liberty to... our posterity" (NOTE TO "T-TYPES" [some of you know what I mean]: "Posterity" means your offspring and future generations; it doesn't mean your backside, and the word is NOT "prosperity.")
Indeed, those very words--"our posterity"--stand as the fundamental reason under Heaven for opposing libertarianism, along with Shariah Islam and Communism (I will deal with other problematic philosophies elsewhere). Those words, ordained and established by the American people, point to a responsibility that goes beyond their own lives and their own generation. When truly considered, that little phrase condemns libertarians in their self-focus, and demonstrates how they are indeed apart from the traditional American vision of liberty. Our Founders looked beyond themselves, and saw their people as just that--A people, singular, with a common identity and duty to their nation. The words indict conservative-minded people whose tolerance and often embrace of libertarianism as a legitimate operative philosophy which does nothing but disable good and empower evil.
One simply cannot hold to the values inherent in that preambular aspiration and be a libertarian.