There is some rather clear evidence that some CSR practices lead to higher stock prices. Refer to Bird, Hall, Momente, and Reggiani's (2007) study in the Journal of Business Ethics, Vol 76, Issue 2, pg. 189-206. Note that the study provides control variables for stock price fluctuation tendencies, accounting for the variance that you claim to make the financial returns difficult to isolate. Additionally, KLD's (see KLD.com) DSI Index, comprised of socially responsible companies, seems to outperform the S&P 500 on a regular basis. You might want to be more careful with your wording when you're writing against the business case for CSR.
Evidence does exist
There is some rather clear evidence that some CSR practices lead to higher stock prices. Refer to Bird, Hall, Momente, and Reggiani's (2007) study in the Journal of Business Ethics, Vol 76, Issue 2, pg. 189-206. Note that the study provides control variables for stock price fluctuation tendencies, accounting for the variance that you claim to make the financial returns difficult to isolate. Additionally, KLD's (see KLD.com) DSI Index, comprised of socially responsible companies, seems to outperform the S&P 500 on a regular basis. You might want to be more careful with your wording when you're writing against the business case for CSR.