More or less political enlightenment thought has been subsumed under "liberalism". Nevertheless within enlightenment thought there was already people who started becoming critics of economic exploitation occurring in the rising post-feudal and post-"ancien regime" societies. Such criticism didnt label itself "socialist" or "anti-capitalist" yet, but nevertheless it became influential in early socialist thought. A main example of this was the thought of english enlightenment and utilitarianist thinker William Godwin who in every historical work on anarchism is included within the anarchist tradition mainly because of his anti-authoritarianism, anti-statism and proto-anticapitalist libertarian socialist views. That could be said to be a radical form of liberalism (meaning against absolutism and anti-feudalism) and another is that of Godwin´s wife, the main englitenment era feminist Mary Wollstonscraft.
In the XIX century there emerged a conflict between pro-capitalist liberal thinkers and politicians who defended a rising capitalist economic oligarchy and a globalizing capitalist market; and on the other hand radical democratic liberals who from then on became known as "radicals" or "radicalism" in mediterranean countries. These latter people wanted things like universal suffrage incluiding the working class and women, land redistribution, separation of church and state and other things now associated with social democracy but rejected by the previously mentioned pro-capitalist liberals. (for more on this see
http://en.wikipedia.org/wiki/Radicalism_%28historical%29) To this day there exist parties who call themselves "radical" parties of this persuasion in France, Italy and Chile who have representation in parliaments.
In the twentieth century the british economist John Maynard Keynes became the main theorist of economic measures associated with western welfare states but he never stopped calling himself "liberal" even though right wing economists of the austrian school such as Friedrick Hayek also called themselves liberals.
Now for more contemporary times I think it is important to deal with the USA only situation of the word "liberal". In the rest of the world "liberals" and "liberalism" are associated with civil libertarianism and neoliberal pro-capitalist free market economics. Only in the United States it happens that what in most of the world are called "social democrats", there they call people who are for a welfare state and keynesian economics "liberals" and people who are for civil libertarianism and neoliberal pro-capitalist free market economics "libertarians". In the rest of the world the word "libertarian" is mostly used in a positive self labeling by anarchists who of course are all opposed to the capitalist system and what they will call "liberals" or "neoliberals" and so this is the reason why there exists things like "libertarian socialism" and "libertarian communism".
I was not born in the US and I do not live there. I just thought it would be nice to inform US anarchists of this latter thing.
