But it's more than that, though. If you closely read the works of some modern-day conservative intellectuals, such as Gingrich or Scalia, you can trace their arguments to, e.g., radical continental (esp. French) philosophy, both 19th and 20th century. A couple of years ago I read an interview where Gingrich basically admits to being a nihilist, albeit driven by his disgust with liberal politics. Truth and facts literally don't matter to Gingrich; his goal is the destruction of the modern liberal state as he sees it; yet, as an intellectual (he's at least well read, if anything), he's naturally driven to rationalize things, so it's unsurprising he effectively ends up in much the same place as, e.g, radical, Marxist leftists driven to develop ideological models in their attempts to undermine the capitalist state and its institutions. In a famous speech Scalia admits he believes American constitutional jurisprudence should reflect French Civil Law jurisprudence, which principally emerged after the writing and adoption of the U.S. Constitution. (Therefore, Scalia's jurisprudence is fundamentally in opposition to originalism, even though it emphasizes textualism and contemporaneous dictionary definitions. It's continental radicalism disguised as American conservatism.)

It all stands out because since its founding American intellectuals, especially mainstream and conservative political intellectuals, have leaned far more heavily toward Scottish Enlightenment philosophy, literally and aesthetically. Americans tended to be more pragmatic, less abstract, and, frankly, generally conservative compared to any of their continental counterparts. Everything about American political philosophy and popular political sentiment has historically been relatively muted; that is, until the modern era that has seen the Republican party ascendent. This has been true even at the liberal extreme--compare Abolitionism, Progressivism, and the American labor movements to their contemporaneous continental European counterparts. (We largely inherited this culture from Britain, of course.)

Likewise, haven't you ever noticed the rather conspicuous conversions of many conservative intellectuals to Catholicism? Or the fact that all the conservatives on SCOTUS are Catholic? (Gorsuch attends an Episcopal church, though.) Even as a Catholic myself, it sort of makes me wonder if the fears of the anti-papists are coming to pass. Of course, Catholicism is very conservative, but it's conservative in a continental European sense, has been shaped by radical continental intellectual dynamics, and culturally continues to have a far larger surface area exposed to radical intellectualism. The Jesuits are great examples of how zealous conservatism can morph into a radical--and even leftist radical--ideological culture. I believe Catholics have risen to the intellectual ranks of conservative factions precisely because they're more familiar with and adept at developing and weaponizing radical ideology. (Relatedly, most of the liberals on SCOTUS are now Jewish, and not coincidentally it was early and mid 20th century European Jewish immigrants who injected radical continental thought into American intellectual circles, greatly influencing the course of American liberalism. There's an obvious stereotyping and prejudice in the types of people the Senate is comfortable confirming, both on the right and the left.)

So it's not just about the adoption and display of "truthiness", it's the deliberate development of ideological arguments and models that undergird "truthiness", in the same manner that conservatives once accused radical mid-century leftists (i.e. Marxists, some extreme feminists, etc) of shaping liberal politics. Nationalist, populist political waves have traveled across the world, but arguably its in America where that wave has a distinctively sophisticated intellectual underpinning, and one might even argue that the global phenomenon originated in the U.S. because of that. Modern American conservatism emerged to oppose mid-century liberalism, but seems to have adopted and recontextualized many of its arguments--moral relativism, identity politics, etc.