[Are our opinions the result of moral fashion?]
Let's start with a test: Do you have any opinions that you would be reluctant to express in front of a group of your peers?
If the answer is no, you might want to stop and think about that. If everything you believe is something you're supposed to believe, could that possibly be a coincidence? Odds are it isn't. Odds are you just think whatever you're told.
The other alternative would be that you independently considered every question and came up with the exact same answers that are now considered acceptable. That seems unlikely, because you'd also have to make the same mistakes. Mapmakers deliberately put slight mistakes in their maps so they can tell when someone copies them. If another map has the same mistake, that's very convincing evidence.
Like every other era in history, our moral map almost certainly contains a few mistakes. And anyone who makes the same mistakes probably didn't do it by accident. It would be like someone claiming they had independently decided in 1972 that bell-bottom jeans were a good idea.
And this bit:
When people are bad at math, they know it, because they get the wrong answers on tests. But when people are bad at open-mindedness they don't know it. In fact they tend to think the opposite. Remember, it's the nature of fashion to be invisible. It wouldn't work otherwise.
These two points remind me of many liberal people I know in New York (and elsewhere): they get their ideas from liberal opinion leaders, and they hardly realize it, and they believe they're open-minded, even though they won't brook disagreement with their adopted views.
Of course, it is hard to see our own faults, so who knows what others would say of me. Of course, sometimes the others don't agree. Some people call me a squish -- a moderate or compromiser -- while others think me an extremist (or put more charitably a strong advocate of certain principles). I actually think in a way both are true.