A progressive is someone who seeks to change the existing order from a liberal perspective.
So define "liberal perspective". Progressivism is antipathetic to personal liberty & rights. It's not liberal at all, except in the sense that it's favored groups gain new inequitable rights & privileges, sometimes/often at the expense of others, always at the expense of egalitarianism.
The fundamental notion of Progressivism is that society can be
better based on the application of science & economics & new social organizations, modernism & leaving tradition aside. That concept seems great, except there is no common definition of "better", and in practice ...
Marxism is the Progressive economic scheme that failed massively. And let's not just account for the economic failures of the USSR & the old Chinese managed markets that kept ppl in needless poverty. We must also account for the violent regime changes and mass murders necessary to eliminate opposition. ~85-100 million in the last century.
https://en.wikipedia.org/wiki/Mass_killings_under_Communist_regimes
Margaret Sangers & Adolph Hilters views on eugenics & human superiority/inferiority - the view that the 'race' can be improved by selectively eliminating ppl from the breeding population, or entirely is a purely Progressive idea. Anyone interested should read the enthusiastic support from English, US & French Progressives for the Nazi movement & Italian Fascists generally. So let's chalk up another ~35million dead and the destruction of Western Europe as a failure of Progressivism. The victims of eugenic sterilization programs in the US & Europe seem an important addenda to this tally.
On to less violent topics.
League of Nations - fail.
UN - a gentleman's C-. (useful at uncontroversial low cost issues like eliminating disease, otherwise a debate society for dictators that has done little to prevent wars or assert human rights).
Social Security, Medicare, Obamacare, Welfare - too early to judge. Certainly there are obvious short term gains to the indigent, but what have these programs done to social cohesion, to family cohesion, to the reduction in charity Are these programs financially sustainable ?
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I see several common themes in Progressivism.
/ It is intolerant of dissent or pluralism, and is therefore anti-scientific. This varies from shouting "denialist" or "racist" thoughtlessly at any dissenter, up to sending people off to ovens or killing fields b/c they fail to fit into the brave new vision of the
better future. They don't see the massive irony in "the science is settled"; but should instead be saying "our minds are closed".
/ It is elitist and anti-liberal. "We elite know best for all" is a strong theme. This is used as a rationalization to use force to impose a new regime. There is a strong element of "appeal to authority" fallacy in many progressive causes (we knoww the thruth b/c some trusted source said so). I can't count how many times I've been lectured on the "fact" of "proven climate problem" by ppl who can't demonstrate a basic understanding of thermodynamics. About as convincing as listening to a parrot.
/ It tends to be driven by zealotry rather than rational, temperate and judicious thought. Marx economics was wrong in many fundamental ways that were well understood even 25 years later. His projections of the future were proven massively wrong. Perhaps a more circumspect and better studied and less violently & immoral scheme could have worked. Genetic testing & giving parents some options at abortion is an example of a less violent and more tempered approach vs involuntary sterilization of "undesirables". I suspect the current approach to climate change management is similarly ill-understood, haphazard - an pointless rush along a wrong path.
/ Progressivism appears to be strongly subject to demagoguery. For every social revision that is proposed there is certain to be political and financial winners & losers. For this reason imprudent ideas are politically promoted by panderers seeking power or money or both. Good ideas don't need pandering ,advertising is sufficient.
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I'm very much in favor of improving society by the application of well founded knowledge & science & the use of reason, however I am vehemently against forcing others to concur with my (or your) view of what is
better. This generally means that government force should not be used, but rather voluntary agreement by individuals.