>The "true market" is like "no true Scotsman" or "a closed system" or "a spherical cow on a frictionless plane".

Come on, what is physics about then? ;)

Even today, systems like my dog are computationally infeasible to predict from the fundamentals, even though everything my dog does is a logical consequence of QED. That's why it is impossible to make progress without assuming a spherical cow and then traveling to every dairy farm in the world in search of the roundest heifer available.

In 400 years economists might still be unable to predict recessions, but I think by then the specific and very true theories of today will have had enough time to evolve into general laws that could predict recessions in principle.