I was thinking merely in the adjectival sense -- as in, progressive means characterizing someone as encouraging progress. I wasn't thinking of the actual movement. I suppose I should have paid attention to the fact that it was capitalized, but at the time, I was being naughty and typing during my archaeology class....
ETA -- I looked back and it wasn't capitalized, so I guess that gives me a little bit of an excuse.
another ETA -- I read through some of the history of the movement, and the distinction from economic liberalism, and I have to say that I agree with some of the tenets I've read so far. The movement was necessary to correct the conditions at the time of its inception.
In my opinion, there is no ideal pure system or ideology that will work in government -- it must be a mix of systems and ideologies that keeps getting stirred, with proportions varying according to the times. In a pure, unchanging system or ideology, there will always be those who figure out a way to get through the loopholes and take advantage of others, much like a parasite keeps trying to infect its host species. By keeping a heterogeneous mixed system in place, and varying the proportions of its component parts over time, the society can respond to new sources of "infection" as they arise, and mix up the best form of resistance.
This is why it is important to keep a society free-thinking, with lots of philosophies. We need as much of a resource-bank of ideas as possible to solve future problems. Times change, and the way we deal with that must change as well.