A progressive isn’t simply a liberal. Liberal as a political identity is so 20th-century, so pragmatic, so Roosevelt-Clintonian. Liberals aren’t allowed to criticize each other apart from Democratic primaries, which all liberals vote in because liberals aren’t allowed to belong to other parties. But progressives pop up in all kinds of parties.
Liberalism has become a way of doing politics. It’s ceased being a real ethos or guiding light. Progressivism, it seems to me, has much more to do with articulating equal rights and equal protection for all.
Chris Cocca 
I know you have a political science degree, but are you using commonly agreed-upon definitions, or just making your own up? (Or using Fox News’s definitions?) Wikipedia describes liberalism as “a political ideology or worldview founded on the ideas of liberty and equality.” Merriam-Webster defines it as “… belief in progress, the essential goodness of the human race, and the autonomy of the individual and standing for the protection of political and civil liberties.”
I think of liberalism as a philosophy that has been driving most of the positive changes in the world since Magna Carta was written, and progressivism as a very specific political movement of the 1930s — precisely the opposite of what you are saying.
I consider myself a liberal (and I consider you a liberal), and I have voted in Republican primaries, though I wouldn’t really claim to belong to any party. (As an independent, I willfully break the spirit of Pennsylvania’s election laws and change my registration as necessary to vote in whichever primary has the biggest distinction between candidate that excites me and candidate that horrifies me.) And despite having voted for far more Democrat candidates than Republicans over my lifetime, I have certainly been critical of actions by Democrats: Obama’s failure to deliver on his promises regarding Guantanamo Bay and other affronts to justice, the Orwellian Employee Free Choice Act, abortion rights, and many other areas. This idea that people who have liberal ideas act as a unified whole is patently ridiculous.
Forgive me for saying so, but it seems like you want to keep thinking of yourself as a conservative despite slowly realizing that nearly everything you believe in (civil liberties, environmentalism, international cooperation, peace, urban renewal, worker’s rights, and the dignity of the poor, to take a few semi-recent topics from your blog) is a liberal cause. I understand; I was there five or ten years ago.
I love your input here.
Whenever we talk about liberalism, we should define terms. I opted not to do that, but I should have.
What you’re calling liberalism is what I would call classical liberalism: it’s the ethos of the American founding with all of the necessary antecedents (John Locke being, in my mind, prime among them.)
What I’m calling liberalism is nothing more or less than Ed Rendell.
What you’re calling progressivism (the Progressive movement of the early 20th Century) is what I’d call Progressivism. There are democrats and Democrats, and in nations where something called a Liberal Party exists, there are liberals and there are Liberals….I’m a republican if I believe that America should be a republic; I’m a Republican if I belong to the GOP.
In recent years, progressive-minded people tired of the baggage that comes along with being called “liberal” have started to talk about themselves as progressives. What I like about this is that the progressive identity weds me to all the things you and I agree on without wedding me to what I consider the party-think of what I’m narrowly defining as having become synonymous with “American liberal.”
That said, I can’t call myself a conservative or a moderate. But I also don’t think of my self as a liberal as such. Semantics are what they are, but there are many conservatives who say they are conservative because they adhere to classical liberalism, and that modern liberalism is really statism.
There’s something to the conservative semantics here. But they’re wrong about American liberalism being statism: it’s actually party-ism.
I love the points you’re raising and how you’re raising them. Thank you.
If “American liberal” means party-ism, you can definitely count me out from that. But if there’s one major US political party that most embodies the idea that someone who does not agree with you on every issue is a traitor, I don’t think it’s the one to whom the label “liberal” is usually applied.
I’ve seen some ugly, recent local fights among liberals more interested in appeasing traditional power bases of the party that finding consensus along progressive lines. Certainly, conservatives do the same.
What do you get when you breed a doormat with a dingbat?
A progressive.