JM: Could we get back to human nature again? I'm still trying to figure out just what is distinctive about human nature. What I mean by ‘distinctive' is: distinguishing us from other sorts of primates, or apes. Clearly Merge – some kind of recursive system – human conceptual systems; in that, we are distinct. Is there anything else you've thought of?

NC: If you look at language, you can find a thousand things that look different. If you look at a system you don't understand, everything looks special. As you begin to understand it, things begin to fall into place, and you see that some things that look special, really aren't. Take Move – the displacement phenomenon. It's just a fact about language that displacement is ubiquitous. All over the place, you're pronouncing something in one position, and interpreting it in some other position. That's the crude phenomenon of displacement – it's just inescapable. It's always seemed to me some kind of imperfection in language – a strange phenomenon of language that has to be explained somehow. And now, I think, we can see that it's an inevitable part of language: you'd have to explain why it isn't around. Because if you do have the fundamental recursive operation which forms hierarchic structures of discrete infinity, one of the possibilities – which you'd have to stipulate to eliminate – is what amounts to movement – taking something from within one of the units you've formed and putting it at the edge; that's movement. So what looked like a fundamental property of language and also looked like a strange imperfection of language turns out to be an inevitable property of language – and then the question is, how is it used, how does it work, and so on and so forth. That's a serious rethinking of perspective. And that's what happens when you learn something about what looks like a chaotic system.