1. It rests on fabricated, though emotionally appealing narratives, in order to generate support. The world is heating up. White people are racist. Recycling cardboard boxes is beneficial. America "rushed" to war in Iraq. Women earn 59% of what men earn -- and, for good measure, this non-fact is attributed to "sexism". Worse, these narratives are arrogantly stated as axioms, and the burden falls on others to "disprove" them.
2. They arrogantly know what is best for you, and will make you pay for it. Public schools. Restrictions on commerce. Penalties and prohibitions against improving your property. They also rely very heavily on the guilt-generating illusion of attempting to help the "other". In other words, "How can you possibly enjoy 'X' when someone, anyone, else is suffering with 'Y'?" And their solution to this "problem" is to take your property and control your behavior.
3. Their "causes" are never in support of anyone; their causes are instead are based on who they hate and are intended to incite. Example: Their 1990s boycotts against South Africa were ostensibly to support the black victims of the apartheid system, but they displayed an utter disregard for the routine slaughters and famines elsewhere in Africa. Conclusion: Their real "cause" was hating white people. Example: They display hypersensitivity to the "plight" of the "Palestinian" people when Israel defends itself against their attacks -- but are indifferent to the far larger number of Palestinian Arabs who are murdered by other Arabs. Conclusion: Their real "cause" is hating Jews.
4. Philosophy and logic are absent, and are instead replaced by base-instinct universal "wants". For example, they want clean air -- as if anyone else wants dirty air. They want "peace", as if anyone (at least in the western world) wants senseless wars. They want "health care", as though anyone else wants to be sick. Even their "positions" are meaningless: Discrimination against gays was fine when one of theirs (President Clinton) signed the Defense of Marriage Act. And war was fine when he authorized (without Congressional approval) the bombing of a European country (Serbia) that was no threat to the United States -- and when he launched missiles at Iraq. Similarly, their objections to the budget deficit under President Bush vanished when said deficit was to become much larger under President Obama.
5. Their support rests on dependency. They create entitlements (actually, coercive government-enforced claims against others) that leave the "beneficiaries" dependent on oppressive government. The main progressive entitlement is welfare for old people; i.e., Social Security. But after being compelled to make "contributions" to this "fund" for their entire working lives, who would want to vote for dismantling it? Who would, after being compelled to pay for Medicare for year after year, would vote to deny themselves this "benefit" when it becomes their turn to collect? What parent, after paying years of real-estate taxes, would want to abolish "free" government schools and subsidized state colleges? And so progressivism oozes along, growing, and using democracy as a weapon to further itself.