Decisions:
"Justice Cardozo wrote the opinions in Helvering vs. Davis and Steward Machine. After giving the 1788 dictionary the consideration he thought it deserved, he made clear the Court's view on the scope of the government's spending authority: "There have been statesman in our history who have stood for other views. . .We will not resurrect the contest. It is now settled by decision. The conception of the spending power advocated by Hamilton . . .has prevailed over that of Madison. . ." Arguing that the unemployment compensation program provided for the general welfare, Cardozo observed: ". . .there is need to remind ourselves of facts as to the problem of unemployment that are now matters of common knowledge. . .the roll of the unemployed, itself formidable enough, was only a partial roll of the destitute or needy. The fact developed quickly that the states were unable to give the requisite relief. The problem had become national in area and dimensions. There was need of help from the nation if the people were not to starve. It is too late today for the argument to be heard with tolerance that in a crisis so extreme the use of the moneys of the nation to relieve the unemployed and their dependents is a use for any purpose
than the promotion of the general welfare."
And finally, he extended the reasoning to the old-age insurance program: "The purge of nation-wide calamity that began in 1929 has taught us many lessons. . . Spreading from state to state, unemployment is an ill not particular but general, which may be checked, if Congress so determines, by the resources of the nation. . . But the ill is all one or at least not greatly different whether men are thrown out of work because there is no longer work to do or because the disabilities of age make them incapable of doing it. Rescue becomes necessary irrespective of the cause. The hope behind this statute is to save men and women from the rigors of the poor house as well as from the haunting fear that such a lot awaits them when journey's end is near."
With these cases decided, Justice Stone could then dispose of the third case in short order. "Together the two statutes now before us embody a cooperative legislative effort by state and national governments, for carrying out a public purpose common to both, which neither could fully achieve without the cooperation of the other. The Constitution does not prohibit such cooperation." "
http://www.ssa.gov/history/court.html
"... promote the general welfare ..."