I've heard it it as synonymous with "good," "new" and anti rich tax policy.
Of course a progressive will think that progressivism is good, and part of progressivism is that it is good becuase it is new (the clue is in the name). Those who are not progressives will hardly agree. And anti rich tax policy is a straightforward left-leaning policy.
It is tempting for progressives to define the word to mean "good" and "new", as it saves them the trouble of defending the ideology. The ideology can then be treated not as any set of beliefs about the reality, but as reality itself.
These days, how many of the people who call themselves progressive think that GMO's are really great because they are new technology?
Half a century ago progressives really liked nuclear power because of the hope that it brings wealth. These days not so much.
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