Given the rather prickly comments in response to this post, I think clarification and expansion are in order. It may take me more than one session. I do thank BC for picking up the banner.

First, term definition. As those of you who followed me at ddjangoWIrE know, I'm very touchy about this subject and get testy when folks throw around appellations like "progressive" and "liberal" and "realist" indiscriminately. Liberals are not Progressives. Conservatives are not Neoconservatives.

How about we start with Disinfopedia's say on the matter:

Liberalism may be used to describe one of several ideologies that claims individual liberty to dissent from orthodox tenets or established authorities in political or religious matters, in contrast to conservatism and/or communitarianism.

1. One usage of the term is for a tradition of thought that tries to circumscribe the limits of political power, and to define inalienable individual rights. This is the most common usage outside of the United States.
   See: classical liberalism or libertarianism.


2. Another, less common usage, is to denote the tradition of various liberal parties. However, though said liberal parties were originally founded on the tradition above, they significantly diverged from it since they came to power in the 19th century, and liberal parties around the world are now based on a variety of unrelated ideologies, so the ideological content of the word depends on the geographical context.
   See: political liberalism.


3. Another, common usage, denotes the ideology of social-democracy, as defended by the Liberal Party in Britain, particularly since Lloyd George's People's Budget. It is with this background that Keynes, though influenced by Fabianism, claimed to be liberal in the 1930s. The influence of Keynesianism on the New Deal has led liberalism to be identified with the welfare state in the United States.
   See: new liberalism.


4. A limited usage is to denote the tradition shared by authors like John Locke or John Stuart Mill, up to the mid 19th century.


5. Some commentators try to distinguish in the "liberal philosophy" (which meaning between 1, 3, or 4 remaining unspecified) a "political liberalism" from an "economic liberalism". These dichotomies perhaps reflect more about the ideology of those who make such a dichotomy, than about the ideology of anyone else.


6. In addition to the political usages above, the term "liberal" is also used in theology to refer to people who hold to views which depart from their religion's orthodoxy.

[In the United States] [t]he common meaning of terms evolve: whereas the word "liberal" was clearly associated to meaning 1 (classical liberalism) in the 19th century, it has come to commonly have meaning 3 (new liberalism) in the US after World War II, and particularly as McCarthyism made the word socialism difficult to bear, and left-wingers massively adopted the name "liberal". For this reason, US classical liberals adopted the name "libertarian". Recently, the word "liberal" has been so much used as a derogatory term by US conservatives that many US liberals (meaning 3) prefer to shun the word "liberal" and call themselves "progressive".

That last sentence is a key one. And IMHO it is deceptive, dishonest, and perhaps even cowardly for Liberals to hide their true colors under a buzzword cloak. At least, I would say, the terms should not be used interchangeably, and Progressives who call themselves Liberals are selling themselves short.
Moving on to Wikipedia's discussion:

Liberalism is a political current embracing several historical and present-day ideologies that claim defense of individual liberty as the purpose of government. It typically favors the right to dissent from orthodox tenets or established authorities in political or religious matters. In this respect, it is held in contrast to conservatism.

The word "liberal" derives from the Latin "liber" ("free") and liberals of all stripes tend to see themselves as friends of freedom, particularly freedom from the shackles of tradition. The origins of liberalism in the Enlightenment era contrasted this philosophy to feudalism and mercantilism. Later, as more radical philosophies articulated themselves in the course of the French Revolution and through the nineteenth century, liberalism equally defined itself in contrast to socialism and communism, although some adherents of liberalism sympathize with some of the aims and methods of social democracy.

Classification in a consistent manner is made difficult by the tendency of the dominant strain of liberalism in a region to refer to itself simply as "liberalism" and reject that identification for other minority positions. Since the word "liberalism" ranges from being highly complimentary to a term of abuse, the connotations of the word in different languages can be starkly different . . .

The original Enlightenment thinkers, such as John Locke and Baron de Montesquieu, were attempting to establish limits on existing political powers by asserting that there were natural rights and fundamental laws of governance that not even kings could overstep without becoming tyrants. This was wedded to the idea that commercial freedom would best benefit the whole of the political order, an idea that would later be called capitalism, drawn from the works of Adam Smith and David Ricardo. The next important piece of the triad of ideas of liberalism, was the idea of popular self-determination. Many liberals are in fact between these wings . . .

The crucial question of liberalism is the question of whether people have positive rights as members of communities, that is, just expectations in excess of being protected from wrong doing by others. For some liberals, especially in the United States, but also in Europe, the modern liberal, the answer is "yes", individuals have rights based on being a member of a national, political or local unit, and have a just expectation to benefits accruing to them, and protections being afforded to them. Other, more classical liberals would answer "no", individuals have no such rights as members of communities, which they call socialism. If individuals have a right as a member of a community, they therefore have a right to expect that that community will regulate the economy, since rising and falling economic circumstances are not part of what an individual can control, if individuals have a right to participate in a public, they then have a right to expect education and social protections against discrimination as members of that public. And so on. Many liberals are in fact somewhere between these answers and differ about the amount of these rights. For example, education belongs everywhere to the liberal agenda . . .

With the 1970s the pendulum had swung away from government action, and towards the use of the free market as the tool with which individuals were most able to protect their self-interest. With the growing skepticism in government, and in corporations, the ethos of self-reliance would find expression in internetworking and in internet discussions.

At present liberalism and its descendants are the most prominent philosophical schools in the west and in the increasingly large sphere of economies and societies linked to them. The ideas of free markets, individual liberties, personal dignity, private property, universal human rights, transparency of government, limitations on state power, popular sovereignty, national self-determination, privacy, enlightened and rational policy, the rule of law, fundamental equality - all radical notions some 250 years ago, and not all completely codified into law until late in the 20th century, are almost universally admitted as the goals of policy in most nations, even if there is a wide gap between statements and reality . . .

The swung away from government action in the 1970s lead also to the rise of the idea described as neo-liberalism, which refers back to the program of reducing trade barriers and internal market restrictions as a way of expanding trade and ultimately opportunity. It accepts a high degree of government involvement in the economy, particularly the acceptance of the need for a central bank and an economy capable national defense, but they seek to reduce government regulation, lower taxes, particularly income taxes. While neo-liberalism is sometimes described as overlapping with thatcherism, economists as diverse as Joseph Stiglitz and Milton Friedman have been described as "neo-liberal". As said before, this economic agenda is not necessarily combined with a liberal agenda outside politics: They often do not subscribe to individual liberty on ethical issues or in sexual mores. An extreme example was the Pinochet regime in Chile, but other examples are Ronald Reagan, Margaret Thatcher, Tony Blair and Gerhard Schröder . . .

So, if you've followed this rather bumpy little path, you can see that, yes, Scoop Jackson, Henry Kissinger, Jean Kirkpatrick, Ted Kennedy, and a bunch of others are really all cut from the same whole cloth.

I should admit perhaps to an error in using "liberal" when "neoliberal" might have fit my argument better. But I stay with my fundamental premise that neocons smell more like liberals than do conservatives.

Stay tuned. More soon.
. . . . . . . . . .
Be at peace