In signaling models, selfish agents might voluntarily supply public goods.
The answer to this question seems obvious to me. I don’t have a PhD. Does that imply that I am clever or dumb? Is this really a PhD level question? Couldn’t children answer it? What am I missing? To what extent does my belief that all human beings are to some extent selfish make this question easier to answer? These are things I think about too much.
That’s PhD question???
To me that is an introductory university interview question, which should be followed up with questions aimed at the analysis of what kind of goods with positive externalities will be supplied more than others.