In 2012, I had a meeting with the National Theatre's Sebastian Born and Ben Power. They talked about the National's plans to erect a temporary, "pop-up" theatre while the Cottesloe theatre is closed for refurbishment. They were after work that might somehow be different; work that might be made in a different way, perhaps. It was an open invitation of sorts. They asked me to go away, have a think and come back to them with perhaps an idea or two.

Up until this point, I had more or less worked in the same way. I would write a play, submit it to a theatre and, if they liked it, they would programme it, and then I would work with a director to make it better. But I wondered if working in the Shed might be an opportunity not only to work with a director in a different way, but also to generate the content of a show in a completely different way.

As I continued to mull, there were two ideas that I couldn't shake off. The first was that I'd love to work again with the director Carrie Cracknell. The second was that I'd love to try to somehow find a way to explore and dramatise some of the material discussed in Kat Banyard's brilliant The Equality Illusion.

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I had read Kat's book when it was first published, and was moved and appalled in equal measure, but simply had no idea how to go about exploring the material in a fictional context. Indeed, I had no idea whether, as a man, I had a right to explore this particular material. Among other things, Kat's book is a startlingly concise, piercingly clear wake-up call-cum-rallying cry to both men and women about the punishing ills of gender inequality.

I felt intimidated and daunted by the scale and the scope of the material. I worried that I wouldn't be good enough; that I wouldn't be able to do it justice. But after a series of conversations with Carrie, we committed to the idea that this was the show we wanted to make. We felt very strongly that we wanted an all-female cast and, when and where possible, an all-female creative team. We also knew that we wanted to generate the content of the show through a series of exercises and improvisations involving our frankly brilliant all-female company.

So that's what we've done. And it has been one of the most extraordinary working experiences I have ever had. The company have been constantly and unashamedly bold and imaginative, and continually honest and open. At times, I have felt like an imposter. At other times, I have been completely bowled over by the breadth and depth of their experiences. The eight women who I have spent the past four weeks working with have a grace and a wisdom and a brevity that is well beyond the likes of me.

Working on this show has also made me consider very carefully my place, as it were, within feminism. If indeed there is a place for me. I have worried and agonised over whether I have a right to call myself a feminist. In her excellent book Feminism is for Everybody, author and campaigner bell hooks eloquently and concisely defines feminism as "a movement to end sexism, sexist exploitation and oppression". Hooks goes on to say: "I love this definition... because it so clearly states that the movement is not about being anti-male. It makes it clear that the problem is sexism. And that clarity helps us remember that all of us, female and male, have been socialised from birth on to accept sexist thought and action."

When I have wobbled over whether or not I have a right to call myself a feminist I have returned not only to bell's book (among others) but also to a single, painfully simple question: do I believe men and women are equal? Bluntly, if you are a man and you have a sister, or a grandmother, or a wife, or a girlfriend, or a daughter, or a mother, I don't know how you can ever possibly answer "no" to this question. It is a wholly illogical response to a simple but staggeringly important question.

And yet, gender inequality persists. In researching Blurred Lines I have spoken to a number of individuals and a number of organisations on a variety of topics. But one of the most unshakeably persistent issues that has, and continues to, haunt and sadden me is that of violence against women. I have found the scale and the constancy with which men attack, both verbally and physically, and rape the women closest to them deeply, deeply troubling.

One the most persistently harmful myths regarding rape is that rapists are strangers, unknown assailants who attack and sexually assault their victims apparently at random. This is a gross distortion of the facts. Last year, 85,000 women in England and Wales were raped. Of these, a staggering 90 per cent knew their perpetrators. Globally, 30 per cent of women who have been in a relationship report that they have experienced some form of physical or sexual violence by their partner.

Men are not born or primed to rape. The intensely saddening truth is that vast numbers of fathers and husbands and boyfriends are choosing to rape; they are choosing to inflict these cruel acts upon the women closest to them. Is it possible to comprehend why these men are choosing to be violent? And, perhaps more importantly, to comprehend how we might go about stopping them?

When it comes to stopping them, we might first look to our judicial system. But even if our police forces and our judicial services were capable of rapidly and effectively dealing with these violent men (which, sadly, they aren't), that would only be solving part of the problem; it would be tackling the symptom but it would not in any way be tackling the cause. In her brutally exhaustive Rape: a history from 1860 to the present Professor Joanna Bourke asserts, "rape and sexual violence are deeply rooted in specific political, economic and cultural environments". One such environment, and one that I will now briefly focus on given that this article is appearing in a national newspaper, is the media.

Take, for instance, the recent gleeful mauling of cook and author Nigella Lawson. Our national press used the case of R v Grillo & Grillo as an opportunity to ridicule and demonise the "domestic goddess" in light of her apparent drug use. But why? In what way is this news? Why did a private dispute between Nigella Lawson and the Grillo sisters find its way on to our front pages? To be absolutely clear: I am, of course, in no way suggesting that the ritual humiliation of Nigella Lawson is directly responsible for acts of sexual violence. I am suggesting, though, that such needlessly vindictive, sexist coverage is worryingly emblematic of larger trend. As one report recently demonstrated, our national media is responsible for "providing a conducive context for violence against women to occur by condoning, tolerating and normalising the abuse of women".

But, you might say, none of this is new. Well done you (white, middle-class, twentysomething playwright) for finally waking up to the unjust world we live in. No doubt, you and all the other well-meaning, left-leaning menfolk will now put a stop to these centuries-old injustices. Even if you didn't feel the need to be quite so sarcastic, you would be right. I am a fraud, a failure and a hypocrite. I did, for instance, as a teenager, view pornography, both in print and online. But I haven't done for years and (for fear of sounding pompous or earnest) I never will again. I am ashamed and embarrassed to say that I have been part of the problem, but I repeat: I never will be again.

Sexism and misogyny are like a virus; their influence is corrupting and insidious. But unlike some viruses, the antidote is deceptively simple: men, including myself, need to take full control of the way we treat women. We need to recognise our failings, accept that we are to blame for the appalling ways in which women are being treated, and we need to stop it. Feminism isn't about so-called man-hating or any of the other nonsense that gets amateurishly slung at it, it is very simply about building and establishing a world in which men and women are treated equally, regardless of race, class or nationality. It is a simple idea with a complex goal. It will likely be fraught and frustrating to achieve, but that's okay. Because we need to do and be better. As Virginie Despentes puts it in her brilliantly blunt King Kong Theory: "Feminism is a revolution, not a rearranged marketing strategy... Feminism is a collective adventure, for women, men and everyone else... A worldview. A choice. It's not a matter of contrasting women's small advantages with men's small assets, but of sending the whole lot flying."

'Blurred Lines', National Theatre: Shed, London SE1 (nationaltheatre.org.uk) to 22 February, tickets from £12