If it were possible to make consistent 10% returns, don't you think this would have happened by now?I am sorry but you aren't really living in the real world if you think that investing is that clear cut. It is all to do with risk. To average 10% return, you would have to have a range of deals some making more some making (a lot) less and then you might eventually average somewhere near 10%.The risk that exists is not all internal - it comes from utterly human and unpredictable factors such as political interference (Fanny May?) combined with behavioural / psychological reactions of the markets. Maybe, just maybe, if every single person on the planet started acting 'socially responsibly' and in a low risk manner, the returns would become more consistent. But then we would have issues of collusion to worry about and firms not acting in an economically efficient manner.From here, you would enter a downward spiral caused by inefficient allocation of resources, and GDP growth would drop significantly. R&D funding would be cut, new innovations start to disappear, and stagnation set in.This would only be brought about through political interference, and we would enter a capitalist market with political, regulatory and behavioural conditions unlike any seen before, and therefore completely unpredictable. Investments that in the 'old' scheme would have yielded 'safe' (predictable) returns will now become a lottery. Unable to invest with an appropriate (or identifiable) degree of risk, credit will dry up (sound familiar?) and capital will no longer go to those firms that need / deserve it. This will not just happen at a macro level, but internal decision making in large firms operates on a similar basis - this really would hit decision making based on efficient allocation of resources practically impossible.Bottom line - I think you're confused about what ethical investment is. It's not about less risk, or consistent risk (in fact investing ethically implies greater risk as there are less investment options open and so hitting the portfolio that lies on the target yield curve is more difficult).Ethical investing is for those that want their conscience clear (be it for whatever reason) and want to invest in firms that typically do not do 'harm' - they operate in an environmentally friendly manner, do not employ children, are nice to people etc. It doesn't imply that they do not make the highest returns possible within their framework.