The 12 year old girl theory is a newly-emerging branch of Keynesian aggregate supply theory which holds that for any product to be successful, it must have immediate appeal to the average 12 year old girl. 12 year old girl theory was developed by the RAND Corporation in response to the harrowing times of the Great Depression as a method to resuscitate the economy. While once controversial, this theory is now a central pillar of modern economics, pragmatic philosophy and The Ten Commandments.