Social Security, is a failed government scheme designed to take money from your every paycheck and give it back when your old and gray. Realistically though, they just take it to paper over interest of the national debt and if there is money left over, they pay off those who have social security coming to them. If there isn't enough money for both, they raise other taxes to paper over this fund. If they still can't come up with enough they simply change the rules of the whole thing (ie raise the %, or denounce befeits, or increase the minimum age to start recieving). All this while inflation lessens your return all the while. In other words, it's a Ponzi scheme.
They tell you that its a reitirement plan, but in actuality, anyone who's taken pre-calc could tell you that 15% of every paycheck until the age of 65 would get you more than you would ever need by retirement by far. If were an actual retirement plan, than there would be no reason for 401k's, mutual funds, IRA's, Roth IRA's ect.
Bush is aiming for a privitation of a small fraction of what you pay into, mainly to appeal to those ignorant enough to not know the math.