The reason for the polarization is because on a large number of major issues each side believes the discussion needs to end because they have come to the correct conclusion.
On abortion, we know that it is the killing of an innocent human being. No further discussion is required. In fact, what should be happening is ending abortion as quickly as possible so that the killing will stop.
On abortion, they know that abortion must remain legal and unstigmatized in order for women to be able to engage as fully in society and the economy as men. No further discussion is required. In fact, what should be happening is a process to make abortion legal and available throughout the country.
We used to joke back in the 70's that when the liberals said they wanted to "dialogue" what they really meant is to lecture us on how they were right and we were wrong. Still, despite this they would actually engage at some level and would even occasionally debate issues.
No more. Intransigency is the order of the day.
When the liberals were in the minority they were the big supporters of free speech and open discussion. Today it is mostly conservatives who are more likely to be free speech absolutists.
What does that say about the state of conservatism?
“The reason for the polarization is because on a large number of major issues each side believes the discussion needs to end because they have come to the correct conclusion.”
This is because those issues are what I call “civilization-defining issues”. There can be no compromise, no “splitting the baby in half” on those issues, because they are matters that people will tend towards an absolute position on, one way or the other, based on their fundamental worldview and conception of morality. The best example of this type of issue in previous American politics is slavery. I’m sure there were people decrying the polarization of the country in 1850, and hoping that both sides would find some compromise, but those types of people, we can now easily see in retrospect, were the short-sighted fools, and the ones who were drawing the battle lines were the ones who could see clearly that the issue needed to be settled before society could ever move past it.