When it comes to market morality, it's hard to make the call between sin and virtue stocks. Particularly with all the volatility that's going on now.

The Vice Fund, which invests in tobacco, gaming, booze and aerospace and defense, is a case in point. The interesting thing about so-called sin stocks is that they are all defensive. People continue to gamble, drink and smoke regardless of what's happening in the economy, and the defense forces keep growing. Which means they continue to perform in volatile times.

No surprises then that the Vice Fund has outperformed funds that invest with a conscience, as reported by the New York Times.

The problem with this debate is that the issues are not that clear. As CFO Europe reports, most chief financial officers and investor relations managers think it's more about brand image and reputation than delivering returns. Most felt that a company's environmental and social policies had little or no effect on market value or ability to raise capital.

One thing is clear. The science determining whether sin is better than virtue is imprecise. Which means this debate will continue to rage for some time.