See all of Slate’s coverage of Mad Men, Season 5 here.

I approached my interview with Mad Men creator Matthew Weiner determined not to fall into the familiar trap of trying to get him to reveal even the most trivial detail about the coming season, which premieres Sunday night on AMC. Instead, I asked Weiner to reflect on what, if anything, his characters have learned over the course of four tumultuous seasons. But at the end of our time together, my curiosity got the better of me. I just had to know: Is account executive Ken Cosgrove still writing fiction on the side? Or was his deliciously titled short story “Tapping a Maple on a Cold Vermont Morning”—published in Season 1 by The Atlantic Monthly!—just a one-off? “We will see,” Weiner said maddeningly. “We will see.”

Slate: I think one revealing way to contrast the great cable dramas of the last decade is by looking at the degree to which they allow their central characters to change. Tony Soprano’s trajectory is different from Walter White’s is different from the city of Baltimore’s. Do you believe that characters can, and should, change over the course of a series? Has Don changed?

Matthew Weiner: You know it’s all about your philosophy of entertainment versus your philosophy of real life. One of the great revelations of The Sopranos for me was realizing that Tony Soprano’s psychotherapy just made him a better criminal. What I like is that on our show the characters are really trying to change. I look at Don and I say he really wants to change. And events have happened. I’ve committed to change in a way that TV shows usually don’t. Don got divorced. No one believed that was going to happen. We left the agency. No one believed that was going to happen. And a lot of that is just the financial realities of TV. They can’t build a new set. They can’t cast another actor. And also why screw with the meat and potatoes of your story? The Don-Betty dynamic—you know, bad marriages can go on for years. But I was bored of it and I felt that he had done enough and this woman would not tolerate it.

But one of the premises of my show is that people don’t change. Don Draper is certainly a creature of external change. He’s an imposter.

Slate: What about Peggy?

Weiner: The woman who put her hand on her boss’s hand because someone in the switchboard told her she’d lose her job if she didn’t sleep with him, versus the woman last year who said “I gave you an idea and you didn’t give me credit for it.”

Slate: She seemed newly indignant.

Weiner: Well, she’s always been arrogant. And I think entitled. And it’s part of why I love people talking about her as a feminist because I think she has no idea that she’s political and she would deny it. She’s just someone who wants what she’s entitled to. It’s fairness. Has she matured and grown? Professionally she’s become more sophisticated. She’s certainly learned a lot about how to do her job. Her personal life? Who knows? In Season 3 she had a one night stand with this young guy and there was some issue about how he doesn’t have a condom. And so she won’t sleep with him.

Slate: If I recall correctly, she suggests “There are other things we can do.”

Weiner: Right. But there was just as much psychological possibility that she would sleep with him without a condom. Because people sometimes “repeat to master”: She would want to have unprotected sex again—and not get pregnant—to undo that problem. It’s human behavior. People want to know how we come up with unexpected twists? We just do the stuff people actually do.

Slate: One of my colleagues noted last year that Mad Men is particularly great at throwing a party: There’s Sally’s birthday party in Season 1, Roger’s infamous Derby Day party in Season 3, the Christmas party last season. Why does the show keep returning to party scenes?

Weiner: I like it as a dramatic device even though it’s hard to pull off— and very expensive—because it’s heightened. Real people are in theater when they’re at a party. There’s instant dramatic irony. There’s instant conflict. Mostly because everyone is being so fake! And then you get the conga line.

Slate: It seems like dancing is important to you as well—Pete and Trudy dancing the Charleston.

Weiner: I think watching people dance is one of the most entertaining things in the world. I grew up on it. I’m never tired of it. The camera was made for it. The camera literally was made to film a couple of things and dancing was one of them.

Slate: Up until last season, we’d seen a lot of sketches and storyboards, but we’d never seen a full-length TV ad made by your characters. How did you go about creating Don’s Clio-award-winning ad for the floor cleaner Glo-Coat?

Weiner: I wanted it to be a groundbreaking ad. I wanted it to look like the ads of that period that were slightly different. That had some expressionism in them and weren’t just like “here’s a rosy perfect world.” Believe it or not, that ad was very personal.

Slate: How so?

Weiner: My mother would clean the floor and we would be locked in the basement. It was a finished basement and everything but of course we didn’t want to be down there. There were toys, there was carpet and paneling …

Slate: So it wasn’t exactly a jail cell.

Weiner: No, this is not Charles Dickens. But it doesn’t mean anything once you can’t go upstairs. We would sit on the stairs and look under the door while we were waiting for the floor to dry, which could be an hour.

I wanted to make the ad a little bit radical and make the audience believe it’s a success. This is the hardest part about creating fake ads. I am not in advertising. You can do a thing when you have artistic work in a dramatic situation where you tell the audience that it’s good. But sometimes they scream bullshit. You do a movie about stand up comedy and the jokes aren’t funny and it doesn’t matter how many people are cheering. At the end of Flashdance when the judges are nodding their heads—I’m dating myself—you believe it because the woman is dancing really, really well. So I always want the ads to be good enough. The audience has to believe that this is a good campaign.

Slate: Several characters had a rough go of it last season, but perhaps none more so than Betty. Were you ever concerned that she would come off as too mean? That viewers wouldn’t be able to sympathize with her?

Weiner: First of all, viewers don’t decide what we do on the show. And what viewers react to negatively does not affect their watching of the show. I want to have good and bad people on the show.

Slate: Do you think she’s a bad person?

Weiner: No, I don’t. I think first of all everyone has a reason for what they’re doing in the show. Her behavior to me is unpleasant but we see a lot more of her private life than other people. And because of that we are looking at our own warts. I always see tragedy for Betty because I think she’s a wasted resource.

I think the tough thing for people about Betty is that her relationship with her kid is too adult. And maybe she shouldn’t have had children. And maybe she should be more motherly and less selfish. But I don’t think people understand: It’s a very recent phenomenon to even suggest that children have a different experience of the world than we do. The whole idea that a child wants x versus an adult is new. And as far as Betty Draper is concerned, that kid has to grow up right away, she does not have to be coddled, she should learn how to behave like a lady, she should learn to be polite. And the great thing is that life is teaching her something different. That girl is very headstrong—and a lot like her mom.

This interview has been condensed and edited.

See all of Slate’s coverage of Mad Men, Season 5 here.