"It's Always Sunny in Philadelphia" (10 p.m., FX): It might be always sunny in Philly, but is it

"It's Always Sunny in Philadelphia" (10 p.m., FX): It might be always sunny in Philly, but is it always funny? We hope that the sitcom about a group of bar owners in Philly is at least funnier than it was in its so-so first season. It launches its sophomore campaign tonight and the good news is that Danny DeVito is along for all 10 episodes.
"The Science of Superman" (9 p.m., National Geographic Channel): This special puts the superpowers to the test, revealing what's plausible based on the earth-bound laws of physics, biology and astronomy, and what's pure science fiction.