OK, let's get this over with. I've made it clear enough that I am not a "Liberal" or progressive so I have to call it like I see it. Nevertheless I want to be as fair and accurate as I can be.
Unfortunately, I have a very dim view of the current liberal movement. But I respect the tradition and it's contribution to American politics so I'll write about that before I disparage the sad state of the contemporary American Left.
In my very first posting I referred to the presidential election of 1932 between Republican President Herbert Hoover and Democrat Franklin Roosevelt. This was the election when Democrats became the "liberal" party and establish the foundation of it's modern incarnation. Republicans had controlled the White House all through the prosperous and peaceful 1920s. Herbert Hoover was a brilliant and popular president, winning the nomination and general election in 1928 by a landslide. He was a moderate, considered part of the Progressive movement but more pro-business than his predecessors. His undoing was that he presided over the stock market crash of 1929 and the ensuing depression.

FDR probably had the election in the bag from the get go. But as part of his campaign he did something that was seen as shrewd but trivial at the time but that would have long lasting significance: He dropped the Progressive label that had become a Democratic heritage with Woodrow Wilson and began to refer to his philosophy as "Liberal." It was a rather far fetched ploy since he was not at all proposing more free market economics and small, less intrusive government, quite the opposite. But the Progressive label had become a liability: Wilson's League of Nations never worked, the Prohibition was a disaster and, worst of all, the Republican candidate Hoover was seen as a Progressive, even if only by association.
Hoover's reaction to FDR was to insist that clearly the Republicans were the more liberal party - more free market and against the League of Nations. And, obviously, prohibition was inaugurated by President Wilson.
But FDR won and ever since then the Democrats have called themselves "Liberals." So what does the term mean in it's new incarnation?
FDR's essential justification for claiming to be a liberal was that he was offering a new kind of freedom that seemed a lot more attractive to most people in those dark days of the early 1930s: Freedom from want, freedom from hunger and unemployment, freedom from fear. Sounds pretty good, right?

To offer this kind of new freedom FDR and his brain trust created dozens of new government agencies to provide new services for the people. The size of the federal government grew 10 times over. Of course, in order to pay for this new taxes had to be levied but they were presented as a temporary measure to solve a crisis. (There's a lesson in that somewhere, I think).
So the bottom line is that the liberals are interested in using the power of government to solve people's problems. At first that was primarily in the realm of
economics but with the Civil Rights movement of the 50s and 60s it was extended into
social issues. The liberals wanted to make sure that no one's rights were infringed upon or denied, to make sure that everyone acted in a liberal fashion, and felt that the government could and should do the making sure.
The dilemma for liberals is that using the government to make people change, even if you consider it a change for good, requires force - and that isn't very liberal.
When it came to
foreign policy, things are even more confusing. Before 1968 the liberals (i.e. the Democrats) were the interventionists and the conservatives were generally isolationists, although both vigorously opposed Soviet communist expansion. Our involvement in WWI, WWII, Korea and Vietnam was promoted and undertaken by Democrats/liberals and opposed by most Republicans. Now it is just the reverse.
So what's up with liberals today? The movement described above doesn't sound too unreasonable, it sounds very good in many ways. For the last 30 or so years the liberals have become more and more radical and coercive, more isolationist and less and less liberal. Fitting then that H. R. Clinton wants a new label. And for once I support her agenda.