The key is "promote" the general welfare. If the founders wanted the feds to ensure general welfare, they would not have written, "PROVIDE for the common defense, ENSURE domestic tranquality, PROMOTE the general welfare...". These words were chosen carefully. Promote means: to contribute to the growth or prosperity of (per Websters). Provide means: to supply or make available. To contribute to the growth of general welfare clearly means to do things that assist the people in growing their welfare or their wealth.