Social Security exactly fits the definition of a Ponzi Scheme. The most recent investors are used to pay the the returns of the older investors.
http://money.howstuffworks.com/question385.htm
http://en.wikipedia.org/wiki/Ponzi_scheme
With the legal precedent established by the examples of the Bernard L. Madoff investment scandal "http://en.wikipedia.org/wiki/Madoff_investment_scandal", the James Nicholson ponzi scheme guilty plea "http://en.wikipedia.org/wiki/James_Nicholson_(Investor)" and various others "(http://en.wikipedia.org/wiki/List_of_Ponzi_schemes)", it is decidedly clear that this is illegal; The money of the Old is not returned to the Old, instead they are paid with the money of the Young. Please abolish this outdated system, born of desperation during the Great Depression.