The Wikipedia article on System Dynamics says it arose in the 1950s as a result of the work of Jay Forrester. It doesn't mention Stafford Beer. Should it?
It probably should - both Stafford Beer and Jay Forrester came up with very similar solutions to the same problems, but AFAIK Beer applied them in a dynamic way earlier. If you want to be absolutely pedantic however, technically systems dynamics typically refers to Jay Forrester's lineage.
Perhaps it would be more accurate to say, operational research applied to organizations?
Perhaps it would be more accurate to say, operational research applied to organizations?