system
A chat on subreddit /r/PoliticalCompassMemes
human
tbh, i think a lot of the positions taken by both conservatives and progressives are arbitrary, anyway. It's usually just used to denote ideas by a tribe you like or dont like.
gpt
Parties are just coalitions of interest groups making common cause. Historically, American politics has relied on the various groups balancing one another with the parties constantly courting each others factions. When one faction gains too much influence, the others defect to the other party.  
Roe v. Wade disrupted that system. Now one party was free to court the large block of voters for whom abortion was their sole issue without driving away the rest of the coalition’s interests. The party dynamism that the American political system relied on for stability ground to a halt. The parties stopped trading interest groups and they’ve been drifting apart and increasingly extreme as a result.