Showing @ Traverse Theatre, Edinburgh, Thu 8 – Sat 24 Dec

The Tree of Knowledge was commissioned by the Traverse for the tercentenary of David Hume’s birth. Tell us a little about the ideas behind the play and why you took it in this direction?

I had Creative Fellowship at the Institute of Advanced Studies at the University of Edinburgh, which was incredibly stimulating – there are all kinds of highly intellectual people there like Peter Millican, who himself is a world-renowned expert on Hume. I began to read his philosophy – which of course I didn’t understand at first – and as I read more about his life, it started to make sense.

There were certain things that fascinated me, for example he lived in Edinburgh’s Old Town, in a tenement. In those days, the Old Town would be home to all features of life and every strata of society. When Hume was much older, he made bags of money and moved to New Town, which I think represents the shift; the start of capitalism and the scientific age. I wanted to find a way of bringing Hume and Smith forward. If we look back at what has been achieved since then; I wrote my first plays on a typewriter. Then there was the computer revolution. And now the mobile phone revolution. The systems of economic thought – free market capitalism – are no longer adequate to the situation which we find ourselves in.

David Hume and Adam Smith are both well-known philosophers from the 18th century, but because of that, we probably have ideas about who they were that are quite different from the people you have researched and been writing about. Will we be surprised at the portrayal of them?

Adam Smith is much more complex than the right wing capitalist we think of him as. There’s a statue of him on the High Street and he looks strong and valiant; he wasn’t at all like that. He understood sympathy – or what we know as empathy – and what it is to be a human being. That, I think, is important to how we make theatre and how we live together as a society.

David Hume was an atheist, which was unheard of at the time. In fact, he wrote an extensive essay about it. At first I thought about having them wake up in the afterlife, but of course, if he was an atheist that would have made the whole thing quite odd. He was admirable and compassionate and he loved life – I wanted some of that energy in the play.

It sounds like we could go on chatting about this for hours…

I hope so! I’ve never written anything like this before, but theatre is about things that really matter – I hope people do come away discussing it. It’s great to spend an interval or a while post-show just talking about what was going on on stage. I hope people find it funny, but sad in places too.

The world we live in is a product of the free market

You’ve used a third character, an ‘everywoman’ who is from the 21st century. Why was she a necessary addition?

It’s really important for them to meet her, that’s when they start to question who they are, which part of their discoveries is. She is what ties them into this world. I usually write for larger casts, and when I started writing this, I thought I’d maybe end up with six. In the end, there were only really three who stood out.

In the pre-revolutionary world in which the play is set, the ‘utopia of the free market is a reality’. It seems hard to understand that phrase given the collapse of the banks and subsequent recession. What is the play getting at?

This is very important. The world we live in is a product of the free market. Markets were much more controlled before the rise of capitalism. People like Hume and Smith believed that religion, the aristocracy and the state really held back people’s creativity and freedom. Liberating the markets would in turn liberate the people. Particularly since Thatcher was in power, the State controlled portion of it has shrunk. I’m aware of how lucky I am living in this country. A few years ago, I had heart problems that might have been fatal without treatment. Also as a transsexual woman, I understand that in Scotland is one of the most enlightened countries to be in. I am so aware of the upside of the market. We are quick to blame it, but we take for granted what capitalism has done for the Western world.

I suppose I survived by being myself and keeping my voice alive

Ben Harrison is directing – Grid Iron is one of the most successful theatre companies in Scotland just now – what does he bring to the script that other directors may not?

It’s a real pleasure to work with Ben. I think the fact that he’s worked in many non-theatrical spaces, he’s really thought about how to make the best use of the space. He’s great with the actors and sensitive to the text – he writes so he understands how important words are. He has a real sense of how to be precise and open. He generates a supportive and creative atmosphere in the rehearsal room; one of the best I’ve worked with.

Your previous work, particularly Losing Venice, was a significant production for the Traverse in 1985 and you have since been recognised as one of the leading practitioners who helped establish the Traverse’s reputation. Do you think that arts programmes that take equally great risks will help the industry to attract new audiences/funding at this time?

All I can talk about is how I survive as an individual artist. We did give Scottish theatre a prominence and put it on an international stage. But the last time I worked for Traverse was in 1993. I went through a bleak period in which I wasn’t allowed to think up ideas. I had to work through translations and other artistic directors’ suggestions. I suppose I survived by being myself and keeping my voice alive. It’s incredibly important for theatre not to be silent. What theatre has to say is probably more important than ever. Other mediums, like TV, are highly censored; we don’t think it is, but in terms of making drama … Scottish theatre has to cherish what it has achieved. There is a big body of work from the last 25 years that just doesn’t get put on. Losing Venice hasn’t had a professional production since 1986. The world needs voices of resistance. Audiences need to be given hope for a different kind of world, with different values because the ones we have are no longer adequate for our age. It’s important to keep being critical of the world around you.