Public opinion on proposals to allow individuals to invest some of their Social Security contributions is uncertain and unsettled. Fewer than half of Americans say they've heard a lot about this idea and support wavers when questions are rephrased or include new aspects of the issue - usually a signal that people either do not understand a proposal or have not thought carefully about its implications. Some poll questions find majorities support a stock-market option. But support declines when questions refer to possible risks, such as the unpredictability of the stock market, reduced benefits and the possibility of the government borrowing trillions to set up the program. Similarly, the number of Americans who say they would personally invest some of their Social Security tax contributions declines when the question refers to the risk of lower benefits. And a survey of investors finds their support for the proposal has significantly declined since 2000. If the proposal were to become law, four in 10 Americans seem to believe it would have no effect on them.