Stephan Pastis believes that humor is incongruity. The creator of the syndicated comic strip “Pearls Before Swine” and author of “Timmy Failure,” a four-book middle-grade series, loves a character with a blind spot.

“I like a narrator who thinks he’s one thing he’s not at all. The wider you make that go, the funnier it is,” Mr. Pastis said on the phone from his home in Santa Rosa, Calif.

The “Timmy Failure” books push incongruity to the limit. Timmy is a dumb detective who can’t solve his cases. With the polar bear Total, Timmy runs the detective agency Total Failure, Inc.  Despite that unfortunate surname, the agency’s slogan is “greatness.”

Readers laugh as Timmy, who is more Inspector Clouseau than Encyclopedia Brown, misses every clue. The series is composed in the style of Jeff Kinney’s “Diary of a Wimpy Kid,” which mixes diary-like narration with comic-style illustrations.

Mr. Pastis will speak Sunday at 2:30 p.m. in Oakland as part of the Pittsburgh Arts & Lectures Kids & Teen Series.

He spent 10 years practicing law as an insurance defense attorney, work he described as being “at the center of a misery vortex.” Unhappiness with work pushed him to pursue his childhood passion: comics. “Pearls Before Swine” debuted in 2002 and won the 2003, 2006 and 2014 National Cartoonists Society award for best comic strip. The first “Timmy Failure” book was published in 2013 and made it to both The New York Times and National Indie best-seller lists.

For Mr. Pastis, “humor works intuitively” but isn’t easily summoned. He distracts his analytical brain with loud music in order to write and draw.

“Very little good creative stuff comes from that logical part of your brain,” he said. “I play loud music to get the other part of the brain to come out — the part that comes out when you’re on a long drive by yourself.”

Despite Timmy’s silly antics and bungled investigations, there’s a serious side to the series. Timmy’s mother is single and struggling to find a job and pay her rent; Timmy is a strange kid who doesn’t have many friends.

“What I’m proud of,” he said, “is that there’s a story under that story and there’s a complex character hidden under the dumb jokes. I like a book that can work on two tracks for a kid.”

There’s plenty of humor that goes over the heads of younger readers. Each chapter title in “Timmy Failure” puns on a cultural reference; Timmy’s advanced vocabulary combines antiquated insults with corporate jargon.

And Mr. Pastis doesn’t tone down his writing for kids.

“In no way do I write for kids. I see myself as writing for me and trying to make myself laugh,” he said. “Emotionally I’m about 12, so I’m somehow talking to my peers.”

Unlike Timmy, Mr. Pastis is self-deprecating about his success.

“I don’t think I’m particularly smart or clever, but I think I’ve figured something out. I just write what I like and hope other people will like it. That’s just a rule. You have to do your thing because otherwise, what is your contribution?”

Julie Hakim Azzam (@JulieAzzam) is a visiting lecturer in the English Department at the University of Pittsburgh.

First Published: February 19, 2016, 5:00 a.m.