When I was about 18 and started to think for myself, I realized that we are way too far in one direction in this country and I should basically always vote/argue the other way.
Our country and especially our cities are made for cars, and we're seeing that become unsustainable in many ways. Anything that brings us fewer cars and more walkers, bikers, and public transit takers, is a good thing.
We as a country are (to borrow some words) racist as hell, we're only slightly less sexist than we are racist, we've got a lot of generations of both "isms" (and many more) to start undoing.
We flex our military muscle too much and end up creating as many problems as we started with (at huge cost to veterans on our side, and civilians on theirs, and at huge monetary cost to our country).
We really ought to do as much as possible to help the world as a whole, environmentally - and not just save spotted owls, but think about the environment holistically and do things in the direction of helping it.
Inequality's a big issue. Our world would be better with way higher taxes, especially on the rich.
(probably more similar things too.)
And like, I still feel like these views are 95% correct. Just... sometimes they're not. Hearing about an anthropologist who studied with a tribe in the Amazon and wrote some pretty unflattering things, I'd have been inclined to say, yeah, probably the unthinking eye of colonialism talking. But maybe it wasn't! Similarly, sometimes we should do a military thing, or build car infrastructure. Remembering that I'm operating with simplifying rules that are only 95% correct (and that percentage may even shift over time) is maybe one way to avoid being smug.
(Not even getting to things like "gentrification" where it's unclear if we're even looking at the right side of the problem, let alone whether it's gone too far. Digging into zoning laws and city hall and taxes is way harder than writing a snarky thinkpiece about an Apple store.)