Democratic politics are often a mixed-bag; some who call themselves "liberal" could list core views like multiculturalism, compassion, moral pragmatism or nonviolence. But others come to the party simply rallying around key policies: they are members of a union, or have a personal stake in the cause for same-sex marriage or immigration reform, and may not, in other areas, identify as ideologically liberal.
I was very young when I started seeing myself as a "Democrat." My parents were both independents. It was a time leading up to the 1996 Presidential election, and I was in fifth grade. One day my mom told me the basic differences between Democrats and Republicans in as neutral terms as she could: she said that Democrats support higher taxes, especially on the wealthy, to support poor people - and Republicans want low taxes.
My younger sister chimed in: "so Republican is 'R' for 'Rich!'" I grew up in a Roman Catholic household and had a spiritually-based belief in shunning personal wealth and living with basic kindness and charity - I saw a perfect world as being based on such - and to me there was little ambiguity that it made me a "D."
I've since moved on (I no longer call myself Catholic - I'm agnostic) and I no longer see "liberal" as an ideological term referring to one's personal vision for an ideal, equal society. I've given up on the idea that the world will ever be perfect, or even that it moves inevitably closer to perfection. History shows that the world can indeed turn for the worse.
Instead, "progressive" is my word for a view based on pragmatism and observation: on what "works" in public policy, as well as a willingness to change one's approach if something else (even something that is an ideological strong point of the other side) would work better for fair access to opportunity, for economic efficiency, for responsibility, for human development and bettering quality of life.
Growing to be less ideological meant I became more friendly to the idea of markets, which often, though imperfectly, allow a rapid response to demands and needs. I don't, however, think that there is really any substantial anti-capitalist ideological movement in America, so one's position on capitalism vs. socialism, or the ideal "distribution" of wealth (as politics are quaintly summed up by the Right), does not truly define party identification.
I think government should do what only government can do best: provide "free" (or universally-accessible) education, "free" (or universally-accessible) healthcare, "free" (or universally-accessible) assurance that a permanent disability or old age does not lead to destitution or homelessness, "free" (or universally-accessible) public transportation so that people are not confined to having their tax dollars go to a system that they can't benefit from if they don't want to drive, etc. Meanwhile entrepreneurship and profits are not at all bad things.
There once was a time that more people worked in one career for a lifetime, so encouraging workplaces to provide health benefits and pensions was the best way for employees to access basic necessities in the world of risk. Now employers want the flexibility to hire and fire at will, the public is calling for a freer market that lets companies "fail" in bankruptcy, and my generation expects to have multiple careers over a lifetime, to travel and to try and do many things. That makes it a time to shift basic assurances like healthcare and retirement from employers, to government.
Republicans and Conservatives say their values are personal responsibility, self-sufficiency, freedom, liberty, economic choice, family and limited government. Those are all positive things! Looking only at that list of terms, Republican values are probably more consistently well-defined than those of Democrats, who have more drastically different reasons for identifying with their party. And in fact, it is easy to be a liberal Democrat and have all those words listed among your core values too.
So why do I find Republican policies so wrong? Because they cling to opposition. There's nothing about "personal responsibility" that says that a publicly-funded healthcare system is wrong and a privately-funded one is right. There's nothing about "economic choice" that shouldn't allow the existence of some publicly-owned institutions for people to choose from. There's nothing about a belief in a free market that says employees shouldn't be able to form unions and collectively bargain for higher wages. (Is the ability to join a union not also an "economic freedom?") There's nothing about believing in "family" that says same-sex couples shouldn't be supported in forming families. There's nothing about "liberty" that says burning fossil fuels must not really be affecting global climate.
There's nothing about "limited government" that says you cap taxes at exactly 28% or 30% or 35% - that line can be drawn where the needs of a given time or place require. A progressive policy maker might raise or cut taxes, or even do both over the course of a decade or generation. Nor does "fiscal responsibility" entail a permanent forbiddance of public debt or deficits. Progressivism, I believe, is a core belief that accepts that situations change.
In my view, Republican policies end up being not a manifestation of values but an interest in negating, somewhat arbitrarily, a lot of things that don't fit their ideological tone - it's not a platform based on principles, it's a platform based on the explicit exclusion of considering other principles.
So reflecting on why I am "progressive," - an identity that could never be taken without historical context - I say it is that I base my positions on affirmative observations and not permanent negations. It's based on what is required NOW - an American liberal might move to Germany and find herself identifying with a center-right party, or to Egypt and find herself identifying with anti-government groups. It's about, ultimately, being able to react to a changing reality.