Is Social Security a Ponzi Scheme? [POLL]

Governor Rick Perry has been under fire for calling social security a Ponzi scheme. However, he has a new vocal supporter who agrees with Perry's assessment. According to The Hill:

Social Security fits the technical definition of a Ponzi scheme, Rep. Paul Ryan (R-Wis.) told conservative Laura Ingraham on her radio show.

“It’s not a criminal enterprise, but it’s a pay-as-you-go system, where earlier investors — or say, taxpayers — get a positive rate of return, and the most recent investors — or taxpayers — get a negative rate of return,” he said. “That is how those schemes work.”

To someone my age, it sure does look like social security is a Ponzi scheme. What do you think? Is social security a Ponzi scheme?