The liberal ironist and the Underground Man actually have quite similar failure modes, now that I think about it.
Well, the Underground Man is more of a, “I know you know I know you know…” type of guy, predicting every possible reubttal and trying to ‘dominate’ the conversation in some sense (which is ironic since he’s just talking to himself the entire time in his ramblings).
The liberal ironist is patronizing - publicly, they speak about absolute truths and such, but internally, privately, they explore not just the idea of contingency, but recursive contingency, and down the rabbithole they go.
Now that I think about it further, I don’t think the actual action you’re taking in the moment is much different from say, the type of thinking you might take when you’re trying to get “Cartesian certainty”. Even though the goals are diametrically opposed, the liberal ironist goes through very similar motions in practice. Trying to achieve a design, and searching the space for constant counterexamples to imperfect designs, are one side of the same coin - it’s just whether or not you believe that end goal is real or not; either you target the end goal, or you believe in the process.
Ultimately though, I think these kinds of mindsets are poisonous. I think the Underground Man is less poisonous than Rorty, funnily enough - but it’s less acitonable. Ultimately, even in the most charitable case, it’s a battle between people who have increasingly and increasingly sophisticated systems of how the world “should” work, yet necessarily quotienting out things they think are useless and yet ultimately causing some type of harm.
Rorty has an interesting approach insofar as we should get rid of the final “shoulds” in vocabulary, but (and this is the reason I framed it as “shoulds”) imposes constant engagement as the solution. “Pragmatist” in the sense of action preceding representation/foundations, but not really a practical solution.