Let me begin by defining my terms. There is a difference between a Libertarian and a libertarian: a Libertarian is a subscriber of the Libertarian Party platform, while a libertarian is someone who believes in limited government. A "libertarian" can be a conservative Republican, but a conservative Republican cannot be a "Libertarian".
The Libertarian Party prides itself on being the only "pure" party that believes in both individual rights and economic freedom. While the Libertarian will concede that the conservative Republican has proper economic views, the Libertarian dismisses the conservative position on many social issues. If the Libertarian Party claims it is the only party which supports liberty, how come the beliefs espoused by the Libertarian Party border on authoritarianism?
For instance, the Libertarian Party supports state-sponsored gay marriage. Rather than rejecting the role of government in marriage, Libertarians encourage expanded government involvement in a realm in which it has no formal powers. Libertarians believe that the cause of "equality" overrides the principle of a limited government confined to its proper role. In response to my claim, Libertarians often say, "It's [state-sponsored gay marriage] better than nothing". That logic simply makes the fallacy that it would be better to increase government power if the ends--"equality"--justify the means--an improper use of the state.
Libertarians proclaim that their option is better than what conservative Republicans propose. Stating that conservatives are simply against gay marriage is false: conservatives are against state-sponsored gay marriage. Instead of forcing the state to accept both straight and gay marriages, the conservative argues that the government should not expand its powers and allow the individual churches to decide who they want to marry. The 'Defense of Marriage Act' is an example of conservative Republicans being against state-sponsored gay marriage: it prohibited one state being forced to accept the gay marriage of another state as the "full faith and credit" clause of the Constitution would mandate. The 'Defense of Marriage Act' would also prevent the federal government from being forced to accept gay marriages (which, the federal government also has no role in). Bob Barr, who was a Republican that turned in to a leader of the Libertarian Party and their Presidential nominee in '08 even agreed with the Republican reasoning when discussing his support for 'The Defense of Marriage Act' and Proposition 8:
"Indeed, the primary reason for which I authored the Defense of Marriage Act in 1996 was to ensure that each state remained free to determine for its citizens the basis on which marriage would be recognized within its borders, and not be forced to adopt a definition of marriage contrary to its views by another state. The decision [Proposition 8] in California is an illustration of how this principle of states’ powers should work."
However, back when Bob Barr received the Libertarian Party nomination for President in 2008, he opposed his sponsorship of the 'Defense of Marriage Act' for partisan purposes.
To Libertarians, the 'Defense of Marriage Act' was seen as an assault on civil rights. To me, it seems as if the conservative Republican would rather stunt the growth of government than expand it.
Another popular social issue is drug legalization. Libertarians support the taxation and regulation of drugs (mainly marijuana). The taxation would be an excise tax on the marijuana being purchased. Libertarians, again, argue the results: "people will be able to buy drugs so we are fine with them being taxed". And again, the Libertarians do not seem to understand that they are fighting for an expansion of government power. They are literally supporting taxation. Libertarians are again compromising their principles--this time, in the name of "social justice".
Conservative Republicans, so we're made to believe, want to keep drugs illegal; however, that is against the principle of individual responsibility that conservatives hold dear. Because of this inconsistency, many conservative Republicans are adopting more lenient drug policies (Ron Paul and Gary Johnson come to everyone's mind). It has also been proven with the legalization of medical marijuana in conservative Republican Arizona that conservative Republican support for drug legalization is growing. Even more important is the conservative Republican opposition to excise taxes, which the Libertarian would support in the case of drug legalization.
Perhaps the most controversial split between the Libertarian and the conservative Republican is the topic of abortion. Instead of realizing Roe versus Wade created legislation which took rights away from the states and put it in the hands of the central government, the Libertarians frequently remark that there should be an unrestricted right to an abortion. By not agreeing with the conservative Republican that Roe versus Wade was an unconstitutional ruling because it was outside of the Supreme Court's jurisdiction to construct legislation, the Libertarian supports its provisions because it aids their belief in the "ultimate liberty" of the mother. Again--the ends justify the means. This compromise on ideas extends in to the actual content of the abortion debate as well.
Libertarians hold the "non-aggression axiom/principle" in high esteem when they are discussing why America should not engage in wars--even if due process deems that the enemy is viable. The Libertarian says you cannot force someone to do something if they have not explicitly contracted and consented to the action (I believe this applies to an action that could be constructed as forceful as well). This logic, contrarily, does not transcend to their beliefs regarding abortion. If they were consistent in their views, the Libertarian would argue that since the fetus is unable to consent to its termination, it cannot be aborted; however, the Libertarian believes that a fetus does not have intrinsic human value, the same way a human involved in a war does. Conservative Republicans who are against abortion believe that there is a larger connection between the "right to life" and "liberty" than just being placed near each other in a sentence. The conservative Republican is against abortion because it shows force against a non-willing participant who has not been condemned by any kind of judicial or legislative action. The Libertarian overlooks this hypocrisy of principles entirely.
No matter what the topic, the Libertarian seems to compromise his own principles. It seems to me that the conservative Republican is far purer than the Libertarian "libertarian".
If you have any more issues for me to discuss here, please leave a comment.