[algesten]

Humans behaviour. A gazillion synapses interconnected together first directly in our brains and then by being part of a context.

I think it's like building a model accurately predicting the grains of sand around the world. Sure, theoretically we can get really really good at measuring everything, so we pretty much know where all those grains are, but I suspect we're not close.

Instead we must do, as you say, "decent approximation" – and this is where my line comes in. I think the crudeness of our current models to predict human behaviour are equivalent to roughly knowing where the Sahara desert is.