At age 79, Woody Allen just keeps the movies coming. In “Irrational Man,” his 45th feature film as a director, he leans once again toward the serious side. It opens on July 17, after premiering at the Cannes film festival earlier this year to somewhat mixed reviews.  The movie stars Joaquin Phoenix as Abe Lucas, a college philosophy professor who’s depressed by the meaninglessness of everyday existence, even while an alluring student, played by Emma Stone, is trying to seduce him. As happens in Woody Allen movies, a chance encounter changes everything. Abe overhears a stranger’s conversation and finds new purpose and vigor in resolving to help the stranger anonymously—by doing something morally questionable.  In his films and other writing, Mr. Allen has forever been obsessed with the purpose of existence. This movie’s title comes from a 1958 book by William Barrett called “Irrational Man: A Study in Existentialism,” which first explained the angsty modern philosophy to America, a book the filmmaker has credited with “popularizing a subject so a mental cretin like me can get it.” The movie echoes themes that have cropped up in some of Mr. Allen’s bleaker films, including “Crimes and Misdemeanors,” “Another Woman,” and “Match Point.” Mr. Allen spoke by phone this week about the new film and what’s next. Edited from an interview.  Some reviews out of Cannes called “Irrational Man” a “light comedy,” but this isn’t a jokey movie. Is it possible—even after you’ve made so many films filled with sorrow, betrayal, moral choices—that you still have a hard time getting taken seriously?  I do. When I started out, I wanted to be a dramatic writer. My heroes were Eugene O’Neill and Tennessee Williams and Ingmar Bergman. I had no interest in comedy, but it’s where my talent was. It was the path of least resistance. People want comedy from me and still interpret things I do as comic when of course they’re not. I remember doing “Match Point,” which seemed to me in no way remotely amusing. It was a serious story about a poor guy who winds up in a terrible jam and kills people. At the Cannes film festival it was very well received, but while the film was on there were any number of laughs. I believe people laughed because they thought they would be missing something if they didn’t laugh. Same with this picture—there’s almost nothing funny. But it will always get some laughs because people associate me with that.  The jazzy music does give it a light feeling. You use lively Ramsey Lewis tracks rather than, say, a requiem.  If we put a requiem, people would be fleeing up the aisles. We did the usual thing. When I finish a film we cut it together, and then I go into the next room and I pick out some record albums from a vast collection I have in my cutting room, and we put down some music next to the picture, what we think may work. We put down Ramsey Lewis because we thought that might be one contender, and all of a sudden everything came together. Picking music is hunt and peck. Often we’re very wrong. When I did “Love and Death” I first put Stravinsky behind it, and Stravinsky didn’t work because of all the atonality and dissonance. When we put Prokofiev behind it, it sounded Russian and came together very well.  Are you self-educated in the literature, music and philosophy you work into your films?  I am self-taught. I was thrown out of college in my freshman year. When I was younger I was a comic-book reader exclusively and never read any books at all. That’s one of the reasons I flunked out. I found when I started dating girls, all I could talk about was batting averages and Superman. The women I started dating spoke about novels, philosophy, culture, music, theater. In order to keep up with them I started to educate myself—out of social survival.  Are we going to see you acting in any more of your own movies?  I sure hope so. The one that I’m going to shoot this summer [an untitled project with Jesse Eisenberg, Kristen Stewart, and Bruce Willis], there just was not a part for me. This becomes a serious thing when you get older. When I was younger I was right for everything I wrote, practically. I could get the girl, I could be flirtatious, I could be the hero. By Dec. 1, I’ll be 80 years old. When I write my movies I can’t find parts for me to play. I don’t wanna play gramps, the backstage doorman, who gives the lover the chorus girl’s phone number. I don’t want to play the benign uncle at the Christmas party. I would like very much to be in some more comedy films of my own, because I think I could be funny.  Is it true that you keep a drawer full of movie ideas on scraps of paper?  That’s exactly what it is. Right now I’m in London. I could be having lunch here and have an idea and copy it down on a piece of paper. It could be a napkin. I’ll throw it in a drawer at home. When it comes time to write I review all these things I’ve accumulated in the drawer. Some of them do hold up and I make those into movies very frequently. You can’t afford to waste an idea if you’re a writer. I’m hoping that I’ll get a chance to keep going and still inflict a cluster of them on the public.  This question might seem morbid, or existential. Bergman made a self-declared final film [“Saraband”] that some consider to be his closing statement. Do you ever think you might do that?  No, I work differently. I just work year after year, and so far it seems, unless I don’t know what’s going on, that I’m in good health. I feel energetic. My dad lived to slightly over 100. My mother lived to almost 100. My guess is I’ll just keep working as long as people keep backing me. I have a lot of stories I’d like to tell. I don’t see myself building to any definitive statement or swan song. I see myself, you know, dying in the saddle.  Write to Don Steinberg at don.steinberg@wsj.com
An Interview with Woody Allen: As ‘Irrational Man’ is released July 17, the filmmaker talks about his less-funny movies, picking music and how we won’t retire.