Epstein and Axtell, in Growing Artificial Societies, get all hyperbolic about the impact agent-based modelling has on 'Explanation'.

For many, explanation and prediction are the same thing, and one can see why: to ask any more of explanation is impossible. Explain gravity! Well, here are some lovely predictive rules. Yeah, but what is it, really? Well... here are some lovely rules? Explanation also seems intuitively at home with reductionism: why are there so many different types of atom? Coz they're formed from smaller exchangeable parts - look, here's how it works.

But Epstein and Axtell reckon they have a new form of explanation in agent-based models: it's 'generative explanation'. Epstein has a whole book on this one idea, but it also appears in their much earlier stuff just mentioned:

What constitutes an explanation of an observed social phenomenon? Perhaps one day people will interpret the question, 'can you explain it?' as asking 'can you grow it?' (Epstein & Axtell 1996 p.20)

Just asked, as a slightly sarcastic aside, on the Simsoc list:

Why exactly do we build models? What's the actual purpose?

(Not that I do yet, but...)

Someone responded:"Why do we build models? I have a quote. I have substituted theorist for artist."

The [theorist] will endeavor not to show us a commonplace photograph of life, but to give us a presentment of it which shall be more complete, more striking, more cogent than reality itself. To tell everything is out of the question; it would require at least a volume for each day to enumerate the endless insignificant incidents which crowd our existence. A choice must be made—and this is the first blow to the theory of ‘the whole truth’.

-Guy de Maupassant

Still in the Lake District at the Complexity Summer School - day three now. Gosh, quite a long way to go. There's a small but significant chance that my brain won't make it to the other side. Here's hoping.

(I've been keeping a school diary on the laptop, but I'll edit this into a 'conclusions' post after its all done.)

So: quick general report, before going on to the model my project group is working on - a model I proposed, so it's quite exciting. For me.