I think Wittgenstein (like most philosophers who aren’t named Plato or Aristotle) is less “underappreciated” and more “completely unknown” once you get outside

I think Wittgenstein (like most philosophers who aren’t named Plato or Aristotle) is less “underappreciated” and more “completely unknown” once you get outside philosophy. Within that discipline, he’s unquestionably the most important thinker of the 20th century and, most would argue, the most important single philosopher since Kant; the entire linguistic turn in philosophy is due to PI. (One can argue, with more controversy, that the “other greatest philosopher” of the 20th century is Quine — it’s hard to imagine the neopragmatic renaissance without him!)