Social Security is structured from the point of view of the recipients as if it were an ordinary retirement plan: what you get out depends on what you put in. So it does not look like a redistributionist scheme. In practice it has turned out to be strongly redistributionist, but only because of its Ponzi game aspect, in which each generation takes more out than it put in. Well, the Ponzi game will soon be over, thanks to changing demographics, so that the typical recipient henceforth will get only about as much as he or she put in (and today's young may well get less than they put in).
Paul Freaking Krugman, 1997. Incredible how much his beliefs change depending on which party occupies the White House.