Newton’s Third Law of Politics

Wasn't it Machiavelli in the Prince who advised that leaders should not only destroy their enemies, but also their friends and supporters so there would be no one left to challenge the leader?

Doesn't really work that way in a democracy, though the Republicans are sure trying- whether it's the Republicans' belief of "us v. them" or telling party members that if they even vote with the opposition they will lose the support of the party leaders and any money for re-election efforts. These actions show that the GOP expects 100% party loyalty and if you're not, then you're an enemy.

To me this is overkill. And does not advance Americans' interests.

The Dems don't demonize members who vote differently and the Dems are open to supporting new ideas which advance the interests of Americans. Whereas the GOP just has a set agenda that can't see reality.

So what it ("Do all political issues elicit an “equal and opposite” reaction from potential opponents?") gets down to is how open-minded people are. The Republican leadership is not open-minded and on social issues wants to control your life- they want you to be straight, anti-abortion Christians who will blindly follow the GOP leadership. The Democratic leadership is much more open-minded and doesn't care whether you're straight or not, for or against abortion, or Christian or not. Just to name a few.

Because the Republican leadership is so rigid in their thinking they see anything else as a threat (including expelling people from the GOP if they don't vote the right way). Generally when people see threats they act much more to the extreme in the name of self-preservation than those who simply see others as having different opinions. Which the far left does see the Republicans as a threat and does act to that extreme. But the Democratic leadership is not the far left, whereas the Republican leadership is to the far right.