liberalism In the classical sense, liberalism is *libertarianism; though the misleading etymological route of ‘liberal’ relates to generosity rather than *liberty. People sometimes assert or assume that classical liberalism is not as *extreme or as theoretically rigorous as libertarianism. But there were some classical liberals who were, at least for some time, more or less *anarchists (though not always using or accepting the label, e.g., Lysander Spooner [1808-1887], Gustave de Molinari [1819-1912], Herbert Spencer [1820-1903], Auberon Herbert [1838-1906)], Wordsworth Donisthorpe [1847-1913], Benjamin Tucker [1854-1939]) and some had elaborate theories (often being the same people). And there are many (most?) libertarians who are not anarchists and many have a paucity of theory (often being the same people). It might still be suggested that a distinction can be made in that classical liberalism is broader than libertarianism because it goes well beyond *minarchy. But many self-described ‘libertarians’ go well beyond minarchy too, so this would mean rejecting their self-descriptions for no apparent reason beyond attempting to introduce a distinction.
The main reason for using ‘libertarian’ instead of ‘liberal’ is the risk of confusion with ‘modern liberal’ (especially in the U.S.). And ‘classical liberal’ can sound obscure or old-fashioned. The rise of modern liberalism began as those who called themselves ‘liberals’ started viewing the *state as also a route to liberty, but often in some alternative sense of that word, rather than merely the main obstacle. This has evolved, or degenerated, into an increasing *ideological muddle that includes parts of classical liberalism, *democracy, *egalitarianism and *political correctness.A Dictionary of Libertarianism