In my view,exogenous variables are not exogenous,pre-determined variables are not pre-determined,and identifying restrictions are generally unjustified. The identification problem is unsolvable at macroeconomic level,so structural equations are not structural.

 

Econometric studies can tell us about variances and covariances,including autocovariances.They can tell us aout correlations,including partial correlations.But they can't tel us anything about cause or effect,impact or influence,structure or meaning.We kid ourselves when we say that one variable helps to "explain" another.This sounds causation,but really only means correlation.