In general I agree with your argument, I just think there are a small percentage of actual sociopaths in the world (I've met one).
> I'm not sure what you are calling the premise and what you are calling the conclusion. But in general, I think that acting in your own self-interest actually results in cooperation with others and not victimizing other people. So we need to be arguing for more rational self-interest. We need to stop making the typical "moral" arguments that amount to, "If you want to be good, sacrifice for others; if you want to be happy, sacrifice other people." That is a completely horrible argument that will never result in anyone being good OR happy.
Sorry for not being clear here. I meant the premise is "Trust is a common good" and the conclusion is "sacrifice for the 'common good' and be good, or help yourself and be evil"