I'm not sure I quite understand, but it's certainly possible the equations that govern economics are sensitive to initial conditions. In that case we will never know enough to specify the initial consitions entirely.
But we also don't need to specify initial conditions exactly to do science.
I'm less convinced that the equations themselves are unknowable.
We also won't be able to specify the outcome precisely even if we somehow had a guaranteed outcome in mind.
Politicians will screw up the implementation, businesses will engineer around it and the alternative solution might ultimately come out to be a better one in practice than in theory.
Trying to define economics by simple equations which you expect to define policy is a lost cause.
But we also don't need to specify initial conditions exactly to do science.
I'm less convinced that the equations themselves are unknowable.