“Do you mind if I do something not attractive?” Ethan Hawke asks. In a vintage T-shirt, with his hair in a half-ponytail, he looks every inch the artsy Brooklyn dad that he is. “I’m starving. Would it be very rude if I eat lunch? I’ll try to be neat and orderly about it.” We’re talking by video chat and I tell him I’ll forgive his lunch if he forgives the noise of kids and dogs in my background. “Never apologise for kids. My two younger ones are Zoom schooling now, so I’m hiding in my office where the dogs are, so we’re even,” he says, tucking into his takeaway.

On the day of our interview, Hawke’s 50th birthday is a week away; if that makes those of us who remember him as a smooth-cheeked schoolboy in Dead Poets Society feel old, imagine how Hawke feels. “Forty-nine sounds a lot younger than 50,” he says with self-mocking mournfulness. Will he celebrate? “My older kids are coming over, so I’ll do a dinner with the six of us, which is about as much fun as we can have these days,” he says.

Hawke has two children, Maya, 22, and Levon, 18, with his first wife, Uma Thurman. He also has two younger ones, Clementine, 12, and Indiana, 9, with his second wife, Ryan Shawhughes, who, as every Gen X-er knows, worked as the nanny when Hawke and Thurman were still an It couple. But if the three of them have moved on from that tabloid saga, so can the rest of us. “My wife and I will go out the next night, maybe we’ll rent a room somewhere afterwards, something like that,” he says, cheerfully popping a green bean into his mouth.

I had been braced for a guarded, somewhat po-faced encounter, as one might expect from an actor who has been in the public eye since the 80s and who does Chekhov adaptations with his friends for fun. Instead, Hawke has the loose, puppyish exuberance of a guy in a dive bar who will keep you chatting and drinking with him well into the early hours.

Despite the passing of years, Hawke still has the same puckish, if increasingly raffish, looks that made him an instant pinup in the 90s, like a choirboy who grew up to be a beatnik. Back then, he seemed destined for the kind of career Matt Damon and Leonardo DiCaprio ended up bagging: commercially successful, but artistically credible. But Hawke’s focus has stayed firmly on credibility over anything else. His best work has often seemed like an endurance test for him, such as his performances as an alcoholic bereaved pastor in 2017’s First Reformed, or a strung-out Chet Baker in 2015’s Born to Be Blue. Even his sparkling collaborations with Richard Linklater take decades of commitment: the 18-year-spanning Before trilogy, the 12 years of filming Boyhood. Then there are the plays he does despite getting stage fright, the novels he writes to gentle acclaim, the Chekhov adaptations. “People are like: ‘Why do you do all this?’ And I’m like: ‘None of these jobs pay, so I gotta keep working – ha!’” he says with a bark of laughter.

Surely it would be the work of two seconds for his agent to get him an easy-money job in a superhero movie, I say. He ponders that solemnly. “But that’s not my dream,” he says finally, then launches into a typically discursive monologue referencing “all my mentors”, who include Bob Dylan (of course), John Cassavetes (inevitable) and, most of all, his friend “Phil Hoffman”, AKA the late, great Philip Seymour Hoffman. Unlike pretty much everyone else, Hawke says, Hoffman didn’t cash out after he won his Oscar (for Capote); instead, he leveraged his new star power to make the indie film Before the Devil Knows You’re Dead, Sidney Lumet’s last movie – co-starring, as it happens, Hawke.

“Why did Phil do that? Because Sidney Lumet was connected to the actor that Phil dreamed of being – Serpico, Dog Day Afternoon, Network. People love it when you’re just obsessed with money, because then they know what your motives are. As soon as it’s about something else, they get nervous. But Phil used his power, not for money or success, but to be serious and substantive,” he says.

Hawke’s latest project is a testament to this mentality. If that sounds joyless and earnest, what he has made is the opposite of both. The Good Lord Bird, which Hawke co-wrote, co-produced and stars in, is a multi-part TV adaptation of James McBride’s novelisation (try to keep up) of John Brown, one of the US’s most famous abolitionists. Brown’s hanging in 1859, for his attempt to start a slave revolt in Harper’s Ferry, now part of West Virginia, was the harbinger of the American civil war, yet no one has played Brown in such depth before – possibly because it has never been clear if he was a genius or a foolish zealot.

One of the best things about The Good Lord Bird is that Hawke plays him as both. In a career not short of highs, his performance as Brown may be his best yet. The typical Hawke character is riven with hesitation and self-doubt: DiCaprio was Romeo, whereas Hawke played Hamlet. Yet his Brown is full of deeply enjoyable fire and brimstone. In a recent New Yorker profile, Hawke claimed that he modelled Brown’s roaring speechifying on his grandfather. Did his grandfather really talk like that? “Well, that’s what I told them. How true it is, I don’t know,” shrugs Hawke, doubtless giving the New Yorker’s notoriously fussy factcheckers a collective coronary.

The tone of the show must have been even trickier to pull off than the performance, because Hawke skilfully preserves the book’s mood of horror mixed with irascible comedy, which works way better than it sounds. Brown’s eagerness to impress Frederick Douglass (played by Hamilton’s Daveed Diggs) verges on the slapstick, while his refusal to fight if it is praying time – and it is often praying time – is a good running joke. “As soon as you tell people you’re making a show about John Brown, they put on their serious librarian face and it feels like you have to play it all dour to be respectful. But the most respectful thing we could do was make a show people want to watch,” he says. And the show – Hawke especially – is extremely watchable.

A series about the US’s history with race feels well timed – although, as Hawke says, when is it not timely for the US to talk about race? But Hawke has been thinking about these issues for a while. He came across McBride’s book when he played a Confederate soldier in 2017’s The Magnificent Seven, directed by Antoine Fuqua and co-starring Denzel Washington. The last time the three of them worked together was when they made 2001’s Training Day, in which Hawke played a wide-eyed police officer to Washington’s slippery detective. Hawke has said that talking with Washington about race during the making of that film was a “powerful education”.

Yet watching Training Day in 2020 is a slightly odd experience: it was made by a black director and stars Washington, but every black character is corrupt or a crack addict and the good guy is, well, Hawke. Does he think it would be made differently today?

There is a long pause.

“People were not as optically oriented as they are now, and there are some benefits for being optically oriented, but it can also [mean there’s] no substance underneath it. Sidney Poitier was shackled with having to be a hero all the time, so there was something liberating about what Denzel was doing. So, if you simplify it optically, you take out what was radical about what Denzel was doing,” he says.

Does he still think it is radical for a black actor to play a corrupt detective? “But you can’t just call Denzel ‘a black actor’. He’s one of the greatest actors of all time – he transcended. He’s a great actor with that Tom Cruise glow and Paul Newman charisma, and him playing a bad guy at that moment was radical,” he says. Hawke is a seasoned professional, but he often talks with the wide-eyed enthusiasm of a fan.

The US’s recent racial reckoning was prefaced by the #MeToo movement, and no figure loomed larger in that than Harvey Weinstein. When the New York Times called Hawke a few years ago to say it was breaking “a big story about sexual misconduct in the movie industry, focusing on one individual”, Hawke replied: “Well, which one is it? Harvey Weinstein or Kevin Spacey?”

Two years ago, Thurman gave an interview in which she said that Weinstein had sexually assaulted her in London in the mid-90s. She also accused Quentin Tarantino of pushing her to drive an unsafe car during the filming of Kill Bill, in which she crashed. (Weinstein has denied Thurman’s allegation; Tarantino has apologised.) Hawke was married to Thurman during the filming of Kill Bill and he told the New York Times he confronted Tarantino about what happened. But did he also know about Thurman’s allegation against Weinstein?

“There wasn’t anything I read from anybody in any paper that I didn’t already know. My ex-wife has spoken up and, put simply, she was very kind. She has much justifiable anger,” he says.

Hawke was born in Texas. After his parents split up when he was four, he lived mainly with his mother on the east coast. When I ask about his parents, he talks with deep feeling about his father’s total lack of interest in fame and wealth. “That was a great thing, because it meant I never felt that, if I failed, my father would then love me less.” His mother, meanwhile, named him Ethan because she thought it would look good on a book cover. When she realised her son liked acting, she pushed him, he says, “towards a British understanding of acting as a craft and away from American ideas of celebrity”.

Between his parents, Hawke learned to take his job seriously, but to maintain perspective about himself, although the latter took time. When he was 14, he was cast alongside River Phoenix in the kids’ film Explorers. The film bombed and Hawke blamed himself. It didn’t help that he later auditioned for Stand By Me. “You’re really good, but I just gave the part to another kid with a bird name,” the director, Rob Reiner, told him. Gutted, Hawke knew who that was.

Did he and Phoenix stay friends? “Oh yeah. You know what you asked me about earlier, why I don’t make easier movies? Well, my first screen partner overdosed on Sunset Boulevard, you know? He was the brightest light and this industry chewed him up, and that was a big lesson to me. If I had to put a single reason on why I never moved to LA, it would be I think it’s too dangerous for an actor like me to be in that kind of climate,” he says.

So many of the best people Hawke has worked with died prematurely: Phoenix, Hoffman and Robin Williams, from Dead Poets Society. I ask if he thinks that is a reflection of the industry or just life. He takes a beat to consider this.

“Drugs and alcohol and depression are formidable opponents all over the world. People think getting what you want will make you happy, but a sense of self, purpose and love don’t come from the outside. You can’t get distracted by this culture that celebrates things that sometimes aren’t what they seem,” he says.

It is bad form, when interviewing an actor, to harp on too much about a movie they made 30 years ago. Happily for me, Hawke brings up a particular film several times, apparently as affected by it as his audience was.

“I brought so much of what I learned from Dead Poets Society to The Good Lord Bird,” he says. “Peter Weir [the director] taught me that producing and directing means uniting people for a common cause of making something beautiful, not who’s got the most closeups or lines. On that movie, we were all in service to the teaching of Mr Keating,” he says, referring to Williams’ character.

Hawke really was terrific in that film, only 19 and barely trained. But when a new generation emerged in the next decade, he already felt washed up.

“When Good Will Hunting came out, I was really jealous, because they had been allowed a decade more to grow, whereas I’d had to do my learning on the fly,” he says. But Ethan, I say, sounding a little more anguished than is strictly professional, if you hadn’t started until the mid-90s, you wouldn’t have climbed on the desk in Dead Poets Society!

“That’s true,” he says, grinning at my panic. “I wouldn’t give up ‘O Captain! My Captain!’ for all the tea in China.”

Seeing as we are comfortably back in the past, I ask if he agrees that his character Troy in the Gen-X classic Reality Bites was a total jerk and not the romantic lead the film seemed to think. “Yeah, I can see that now. But back then the ne’er do well who’s an asshole had a cool factor,” he says, correctly. (See also: Jordan Catalano in My So-Called Life.) “Now every girl would go for the Ben Stiller character, whereas they’d look at Troy and think: ‘That dude’s going nowhere,’” he concludes, also correctly.

More than a little embarrassingly, my aforementioned children have now crashed our interview and, while Hawke finds this hilarious, I am so mortified that I suggest we wind it up. We had gone over our one-hour slot anyway. “Remember, no apologies! But we went deep, didn’t we? We told a story!” he says, as if we had hammered out a screenplay together instead of discussing his life. “Boy, we really went far. Whew!”

• The Good Lord Bird starts on Sky Atlantic at 9pm on 18 November.