Early adopters: Academics, early activists, and fringe thought leaders
Majority: The average person / most people
Skeptics: Laggards, Luddites, and grandmas
Everything was wrong at some point
I think people hate it when I say that. It means there’s a chance that some ideas that you don’t like today may someday become accepted, and even normal. It means that maybe, some portion of your ideology has the possibility of being on the wrong side of history. It’s a call to question all your beliefs and think about why you believe them. The seat belt is one silly innocuous example of something that no one 50 years ago would have thought would be widely adopted. But there are many more provocative ideas that are now widespread, and were hard-fought to get to that point. I mean, Galileo turned out to be right, and he fucking died in jail.
It's certainly disturbing in hindsight that our society was capable of being so tragically wrong yet so certain of its convictions. And while we (America) no longer imprison people simply for saying things we disagree with, we definitely still have the capacity to "know for sure" we are right at the same time that other people "know for sure" we are wrong. The intense partisanship of late is perfect evidence of that. The point is, we can probably agree that as a civilization of partially-enlightened apes, this definitely isn't our final form, and we shouldn't assume everything will stay the same in the future.
That said, here's a fun thought experiment: what is today’s version of Galileo's heliocentrism in the 17th century? Is there an idea that is currently so heretical or offensive or unlikely that you couldn't imagine most people eventually buying into it? We obviously don't have the prescience to predict future scientific breakthroughs or even to sense what ideological trends could be mainstream in the future. But there are some ideas that are clearly up for debate, and it's fun to take a stab at parsing them down to their first principles. And moreover, it's an important exercise to constantly question all standing ideologies, even with just your personal opinion. So that's where the question comes in handy: What important truth do very few people agree with you on?
Here are some random example of ideas and my guess at their current level of acceptance (assuming they could die at any point):