There was a time, right up until the end of the Second World War and beyond, when white people in Europe thought that they basically owned the world and that everybody else was a sort of servant, or a curiosity, or whatever. And that informed 99 percent of the photographic practice that was done. Without being able to address that, I felt I would have failed in my attempt to explain what the urge to document is.

My current project was shot on film, and because of that I've spent my entire day removing dust-specks from negatives. You wouldn't have to do that on digital because you don't get dust on the scanner. I say to myself, "Why am I doing this all day?" I could have just bought a digital camera and I wouldn't have to remove dust-specks ever again. But when you move closer to a film image, it has a real truth to it. And I really like that.

I think, oddly, that the world of the amateur is quite self-contained, and it depends on "likes" from other amateurs to perpetuate itself. Of course an awful lot of my colleagues are involved with Instagram - they get likes and dislikes, maybe just likes, I don't know - but I think that it's far less self-contained, the world I work in. It goes off in different directions, and is dependent on responses different from a tick or a like or whatever.

In the documentary impulse, two species of 'fact' exist side by side: one is coolly objective and the other is fraught, diverse and emotive; one figurative, the other abstract; one prosaic, the other poetic; one factual, the other romantic.

As humans, we need to question all these notions. What does freedom mean for us? What are our responsibilities? It takes one-250th of a second to take a photograph. So I have the whole of the rest of that second - and of that day - to think.

There is a danger in our modern practice of using embedded journalism. As there is less and less money available for journalism to uphold its independence, there is a temptation for people to take short cuts. If this army or that army or this corporation is willing to pay for your flight or your accommodation, then it's much more difficult to tell what the real story might be. I do have a concern about that.

Social media's currency is the single photograph. Whereas, every time I look at a photograph, I look at twenty or thirty photographs. I'm looking for a narrative. And that's a different kind of construct. If you're a poet and you put a line from your poem online, "The trees bending over gracefully," or something, you can get a tick. But that has nothing to do with your longer poem.