They might not think they have, but Republicans have abandoned the ideological underpinnings — fiscal restraint, strength in defense and leadership in foreign affairs and trade, reliance on personal character, and responsibility in social policy and individual behavior — that bolstered four decades of conservative dominance in American governance.

There is no “they.” People with ideological underpinnings are a minority in both parties, but they can provide an important veneer of seriousness for the self-interest of the other members. Republicans who believed in the recited underpinnings in 2008 still believe in them, but they have left the party. They started leaving when Mitch announced that obstruction to make Obama look bad was the party’s highest priority, and the exodus reached full flow in 2016 when the party nominated a man who wouldn’t know an ideological underpinning if it bit him on his adipose underside.

My TLDR on the Federalist: Politicians operate on the maxim “Never tell a lie when the truth will do,” so our constitution is designed to make the truth “do” often enough to maintain faith in the system.

That’s no mean feat, as Jonathan Swift observed, in time for the Founders to read:

Besides, as the vilest Writer has his Readers, so the greatest Liar has his Believers; and it often happens, that if a Lie be believ’d only for an Hour, it has done its Work, and there is no farther occasion for it. Falsehood flies, and the Truth comes limping after it; so that when Men come to be undeceiv’d, it is too late; the Jest is over, and the Tale has had its Effect…[Emphasis in the linked quotation.]

Now, thanks to our modern information dissemination, from social media to profit-driven “journalists,” the truth won’t do at all. (The ironic prescience of “Yahoo!” as an internet brand is astounding.) Was there any good reason to support Trump over JEB or Kasich? Or is there a good reason to support anyone in the Dem field over Bullock, Bennet, or Inslee? (Yes, Democrats are stupid, too; they just react to different bright, shiny objects.)

Trump proved, as populists before him, that meaningful ideological underpinnings are makeweights, useful for winning the day when the masses are happy. But if the masses are angry enough, i.e., if you can make them angry enough by lying to them, any ridiculous “ideology” — “America First”, say — will work; the true believers don’t really matter any more.

Ronald Reagan said it years ago about the Democrats: he did not leave the party; the party left him. Now, the GOP has left its intellectuals, the ones with the ideological underpinnings. No one who actually held those beliefs has abandoned them, but plenty of pols who professed those beliefs have stopped professing them. Those truths will no longer “do.”