How do we define liberalism? It depends on the landscape. Without going further in analyzing tenets, here’s a small trip around the world and around political definitions/labels: American-style liberalism is called socialdemocratism in Europe. Of course, in America the term liberal has acquired such pejorative connotations that now the preferred word used by liberals to define themselves is "progressive." Just like The Finch and Hillary Clinton like to call themselves.
Politics are dynamic, say politicians that like to change denominations just like they change shirts. Nineteenth century liberalism corresponds to actual libertarianism, of course, and that libertarianism pales in comparison to what was experimented in the late decades of the 19th century. Modern libertarianism equals modern liberalism in Europe, i.e., the old laissez faire. Meanwhile, classical liberalism would be now (via Hayek and Mises) the backbone of what is now considered conservatism in America.
Radical in Europe and Argentina is not even half of what a radical in America is. For European socialdemocrats and amid the current crisis specially, anyone who claims to believe in the free market and small government is labeled a neoliberal (a pejorative word strong in Europe and Latin America), and if he/she is not in favor of the European Union, becomes an ultra-nationalist, and if he/she is not defending secularism at all costs, then he/she is an ultraconservative.
Keep in mind that nowadays by definition any conservative in is an ultraconservative. A neoconservative or neocon is a recovering liberal. A paleoconservative is what people in South America call a “godo.” For the socialdemocrats and progressives alike, all conservatives all the same: extremists. But not ironically for conservatives, the liberals, progressives and socialdemocrats are all leftists, and if we have to use the word, commies. And as long anybody is not showing pictures of Hitler and swastikas, or is brandishing a weapon to establish a communist revolution (note that the extremes are asymmetrical), all are considered "center-left" or "center-right," although more than an knowledgeable experts gets in the same bag both the Nazis and the Communists as Nazi is an abbreviation for national - socialism.
The political struggle is easier when we are the reasonable ones are and the others are the extremists.
