We can have a regression in social cohesion and our political stability without necessarily declining. If anything, this increase in short- and medium-term tensions could result in a healthier society in the long-run.
Exactly, decline is marked by stasis not dynamism. Over Trump's presidency we've seen a huge upswing in political/civic participation coupled with a pretty fundamental issue realignment. These might be uncomfortable growing pains, but its much preferable to being stuck in a permanent "end of history" ethos that persisted from Poppy Bush to Obama
