It’s hard to think on television. Or rather, it’s hard to show people thinking, looking at evidence, drawing on their experience and offering their conclusions. It’s hard, but not impossible. The whimsically intelligent series “History Detectives” (8 p.m., PBS) enters its third season tonight, demonstrating that deductive reasoning need not be dull.

Part whodunit and part “Antiques Roadshow,” “Detectives” features a panel of fact-finders – an architect, an auctioneer, a sociologist and an art historian. Each week they are presented with interesting artifacts accompanied by a family legend or unusual history that they are asked to debunk or verify.

In tonight’s first story, sociologist Tukufu Zuberi investigates the claim made by two brothers from New Jersey that their uncle built the airplane engine that carried Charles Lindbergh and his Spirit of St. Louis across the Atlantic in 1927.

Another participant offers an artifact that could be part of Cold War history: a tiny pin filled with poison to be used by spy plane pilots (like U-2 flyer Francis Gary Powers) to commit suicide rather than fall into Soviet hands. And, to make matters weirder, this secret suicide device was purchased at a backyard estate sale!

In the final segment, a woman offers an old photograph that appears to be the legendary Geronimo with her relatives at their New Mexico ranch.

The best thing about “Detectives” is not just the “stuff” and their stories, but the way it celebrates research and the investigative process. Yes, we actually see people going to the library and using a card catalog. And I, for one, found it entertaining.

Tonight’s other highlights

¢ Teens sharpen their No. 2 pencils on “The Scholar” (7 p.m., ABC).

¢ Scientists evaluate a cycling phenomenon on “The Science of Lance Armstrong” (7 p.m., Discovery).

¢ Frank’s tasteless act on “Everybody Loves Raymond” (8 p.m., CBS).

¢ Harrison Ford stars in the 1997 thriller “Air Force One” (8 p.m., ABC).

¢ Russian mobsters on “The Closer” (8 p.m., TNT), starring Kyra Sedgwick.