Here are the schools of libertarianism that have interesting levels of support or influence within the Libertarian Party. Some caveats:
- There are very little data available to quantify this list, so any perception that it is ordered by number of sympathizers is merely a happy coincidence.
- There are rarely any sharp lines between schools, and there are not always standard descriptions of a given school.
- Many, indeed most, Party members don't care about fundamental ideology deeply enough to rigidly confine their views to whatever boundaries a given school might have.
- None of these schools is so well-defined as to specify all of the many Free Variables in Libertarian Theory, so those variables have the potential to combinatorially multiply the number of sub-schools.
Minarchism has come to mean any non-anarchist form of libertarianism. Minarchism is often grounded in the economic analysis of — or at least the recognition of — market imperfection. It is the basis for Brian Doherty's definition of libertarianism as the belief "that government — federal, state, or local — should be restricted in its functions, generally to the protection of citizens' lives against force or fraud and the provision of a small set of so-called public goods that could not be provided by free markets". Public good is a technical term in economics that means not just any collectivized good, but rather one that is non-rivalrous and non-excludable.
Cosmo-libertarianism is the moderate, pragmatic, and loosely-defined variety of minarchism typified by the Cato Institute and Reason magazine, and named for their cosmopolitan (as opposed to populist or paleo) milieu. Dismissed by radicals as "beltway libertarians" or "cosmotarians", leading cosmo-libertarians openly seek to influence the policy-makers of the state rather than rail against its moral illegitimacy. Cosmo-libertarians are less likely than many other libertarians to let either ethical or economic theory trump pragmatic considerations about how to make the most progress in increasing liberty. The term cosmo-libertarian came to prominence in January 2008 in the wake of the Ron Paul newsletter scandal, and cosmo-libertarians don't necessarily embrace it.
When originaly coined c. 1970 by Samuel Konkin, minarchism meant belief in a minimal state whose only purpose was to prevent and punish force initiation without initiating force itself, and that to this end maintained the usual state monopoly on retaliatory force. An important kind of strict minarchism is Ayn Rand's Objectivism. Both anarcholibertarians and non-strict minarchists argue that strict minarchism is self-contradictory because the state's monopoly on retaliatory force could not be maintained without initiated force.
Every variation of anarcholibertarianism takes the prohibition against fraud and force initiation to be absolute, with no room for a state to maintain its monopoly on the provision of defense or justice. In the context of the Libertarian Party, the leading anarcholibertarian theorist has been Murray Rothbard, and his successors led by Lew Rockwell of the Ludwig Von Mises Institute. Their ideology of these and most anarchist Libertarians is grounded in the a priori deontological axioms of Austrian Economics. Another major approach to anarcholibertarianism is the consequentialist analysis of David Friedman, the son of Milton Friedman who argues that even the legal code itself should be the result of market forces instead of a priori principles.
The current LP Radical Caucus generally advocates that the LP should follow the Rothbardian strategy of "holding high the banner of pure principle" — i.e. anarcholibertarianism. The Libertarian Reform Caucus is a coalition of mostly minarchists (but also some self-described radicals and anarcholibertarians) who want to unite under a "Big Tent" all libertarian inclusivists and incrementalists, whether moderate or radical, as long as they are ecumenical toward their fellow libertarians.
'Left-libertarian' describes a cross-section of libertarians who advocate a more egalitarian approach to the ownership of natural resources or capital, or who are influenced by the labor theory of value (in contrast to the standard theory of marginal utility). Left-libertarians tend to disagree sharply with other libertarians on the extent to which an economy like America's approximates a truly free market. Geolibertarianism is a kind of Left-libertarianism.
'Paleolibertarianism' is a term that was adopted by Murray Rothbard and Lew Rockwell in their attempt in the early 1990s to ally with paleoconservatives against shared enemies such as statists, interventionists, and libertine libertarians. Rockbardian theorists have tried to define paleolibertarianism as necessarily anarcholibertarian, but the political leaders they ally with (e.g. Pat Buchanan, Ron Paul) have been uniformly non-anarchist. Instead, those leaders express an outright reverance for the original American republic and its Constitution, in sharp contrast to the revulsion for the American state expressed by true anarcholibertarians. This tension in the paleolibertarian alliance was put under increased strain in early 2008 by the controversy over bigotry in Paul/Rockbard newsletters from the 1990s.
Econ-libertarianism was defined in 1997 by economist Robin Hanson as libertarians who apply "the standard economist's 'Pareto' criteria for preferring one social institution to another: we seek institutions whose consequences make most everyone better off according to their own estimation", in contrast to a priori deontological considerations of natural rights. Econ-libertarianism thus tends to be driven by economic theory and is led by economists at places like the University of Chicago and George Mason University. Econ-libertarians tend to remain somewhat detached from retail political activism and strict ideological partisanship, although the spirit of econ-libertarianism is easily recognizable in the consequentialist anarcholibertarianism of a David Friedman or the geoanarchism of a Fred Foldvary.
Wikipedia aptly says "neolibertarianism is a post-9/11 ideological offshoot of libertarianism that incorporates neoconservative ideas on foreign policy, including the use of preventive military force". Neolibertarianism is much more widespread outside the LP than within it, and many neolibertarians disdain the LP for having views on national defense that are irredeemably skewed by the LP's anti-statist ideology and Vietnam-era anti-war roots. Many prominent LP neolibertarians are members of the current Libertarian Defense Caucus, whose Statement of Principles asserts that "a global war on terrorism exists".
Geolibertarianism follows the tradition of Henry George in holding that land (technically, locations) is distinct from other forms of property, and that possessors of land incur some kind of obligation to those whom they exclude from accessing it. Geolibertarians criticize "royal libertarians" for ignoring the Lockean proviso that when homesteaders enclose, extract or consume from the commons they must leave "enough and as good" for others. The influence of geolibertarianism can be seen in the widespread support among libertarians for a land value tax as the optimal (or least objectionable) way of financing government. 'Geolibertarian' was coined in 1981 by Fred Foldvary, who has developed it into a detailed program with a coherent theoretical basis. The standard geolibertarian reform proposal is called the green tax shift, which is advocated by the Democratic Freedom Caucus and by several leaders of the Libertarian Reform Caucus.