Slate Magazine recently posted a great article on the recently-departed author and essayist David Foster Wallace, focusing on how Wallace (correctly?) interpreted Wittgenstein's early and late philosophy to cope with his allegedly crushing sense of solipsistic dread. I'm not sure I buy this thesis, but Wallace's suicide implies something was clearly bothering him. Even so, I'd ascribe a more clinical complaint like depression than a philosophical one like solipsism.
For anyone who reads the article and wonders whether Wallace (a fellow philosophy grad school dropout) had anything interesting to say about Wittgenstein, here's a clip from his essay "Tense Present: Democracy, English, and the Wars over Usage," as it originally appeared in Harper's Magazine in 2001:*
INTERPOLATIVE DEMONSTRATION OF THE FACT THAT THERE IS NO SUCH THING AS A PRIVATE LANGUAGE
It's sometimes tempting to imagine that there can be such a thing as a Private Language: Many of us are prone to lay-philosophizing about the weird privacy of our own mental states, for example, and from the fact that when my knee hurts only I can feel it, it’s tempting to conclude that for me the word pain has a very subjective internal meaning that only I can truIy understand. This line of thinking is sort of like the adolescent pot-smoker’s terror that his inner experience is both private and unverifiable, a syndrome that is technically known as Cannabic Solipsism. Eating Chips Ahoy! And staring very intently at the television’s network PGA event, for instance, the adolescent pot-smoker is struck by the ghastly possibility that, e.g., what he sees as the color green and what other people call “the color green” may in fact not be the same color experience at all: The fact that both he and someone else call Pebble Beach’s fairways green and a stoplight’s GO signal green appears to guarantee only that there is a similar consistency in their color experience of fairways, and GO lights, not that the actual subjective quality of those color experiences is the same; it could be that what the ad. pot-smoker experiences as green everyone else actually experiences as blue, and what we “mean” by the word blue is what he “means” by green, etc., etc., until the whole line of thinking gets so vexed and exhausting that the a.p.-s. ends up slumped crumb-strewn and paralyzed in his chair.
The point here is that the idea of a Private Language, like Private Colors and most of the other solipsistic conceits with which this particular reviewer has various times been afflicted, is both deluded and demonstrably false.
In the case of Private Language, the delusion is usually based on the belief that a word such as pain has the meaning it does because it is somehow “connected” to a feeling in my knee. But as Wittgenstein's Philosophical Investigations proved in the 1950s, words actually have the meanings they do because of certain rules and verification tests that are imposed on us from outside our own subjectivities, viz., by the community in which we have to get along and communicate with other people. Wittgenstein’s argument, which is admittedly very complex and gnomic and opaque, basically centers on the fact that a word like pain means what it does for me because of the way the community I'm part of tacitly agreed to use pain.
If you’re thinking that all this seems not only abstract but also pretty irrelevant to the Usage Wars or to anything you have any real interest in at all, you are very much mistaken. If words’ meanings depend on transpersonal rules and these rules on community consensus, language is not only conceptually non-Private but also irreducibly public, political, and ideological. This means that questions about our national consensus on grammar and usage are actually bound up with every last social issue that millennial America's about—class, race, gender, morality, tolerance, pluralism, cohesion, equality, fairness, money: You name it.
I was never a big fan of Wallace's fiction, but he was one of the great essayists of our generation. Anyone unfamiliar with his work might want to start with "Consider the Lobster," or perhaps "Host." If neither of these grab you, I doubt anything else will. Here's a clip of him being interviewed on Charlie Rose, where he (trivially) voices some of the same complaints about academia that I suspect the P.E.L. guys share, and (less trivially) reveals interesting aspects of his intellect and personality:
*The essay was later edited and re-titled "Authority and American Usage," and included in the collection Consider the Lobster and Other Essays, which is well worth a Kindle download.