It's difficult to explain George Carlin. To those born after 1980, he was the angry, pony-tailed older man who ranted about religion, greed, dirty words, politics, materialism and politics. 
Older folks - particularly those of the baby-boom generation - will remember him as the comic of their generation: the man who - like the Beatles - started out as a traditional "jacket-and-tie" performer, then changing with the times, becoming a voice of the counterculture.
Putting all that aside (including the Seven Dirty Words), I wonder why today's most successful comedians don't have a similar message. Dane Cook, an incredibly popular comedian among college students, is an entirely different performer. His material focuses on the funny, quirky stuff of life, but isn't as introspective as Carlin. His website, for example, hawks "Dane Cook Gear," offers a donation space for a couple charities (including AnySolider.com), and asks that you vote for Dane for the 2008 Teen Choice Awards. Now I'm not picking on Dane Cook - it's just that he, along with most of the other comics and other artists today, does not openly challenge us to think about our lives, our communities, and our government.
What creates a climate of critical art? Is it the best of times or the worst of times? My guess is that neither one influence critical thought, new ideas and artistic revolution. My feeling is that it's the sense that change is taking place - passing the torch to a new generation, discarding the traditions of an older culture / government, the death of a beloved figure - that moves culture forward.
And after Carlin's death this past Monday, I believe that It's time for a change.