I completely agree that it is not at all obvious what good and bad effects there are of companies' activities. I think it is very possible that some 'unethical' activites have more positive effects than many activities commonly understood as ethical. It would take a lot of reflection to work out what good and bad effects certain companies have. The point of my post was to ask, before engaging with this question, whether individuals' decisions about their investments in the secondary market have much or any influence on companies. If not, it's not urgent to think through the question about how much good various companies do, at least in terms of what influence this should have on your investment decisions.

This may have been obvious to many people from the start, but it wasn't to me.