Recommended reading: The Good Outnumber You; Are we naturally good or bad?; The Bonobo in All of Us.

I think it's more complex than 'good' and 'evil.' I prefer the alternative dichotomy of individualism versus collectivism. As a species, we must have a selfish instinct. No individual can survive without it. But, as we all know, selfishness is 'bad.' Except it isn't. Placing the individual above the group is bad.

We are social animals. Because evolution figured out that we accomplish more by working together, than being alone. Hence, we all also have a collective drive. A desire to care for others, and even put their needs above our own.

I think the classic 'good' and 'evil' can be reformulated as a battle between selfishness and charity, which rages within us all.

people are inheritently awful beings

I don't think anyone is bad. That's the wrong way to look at it. People are broken. For whatever reason – nature or nurture – some people put their selfish instinct above their charity instinct. Most people, even. But to paraphrase Oswalt, enough people are charitable that we have civilisation. For all his complaining, your hypothetical individual probably lives in one of the most equitable, one of the least violent societies in the history of any species, with food and shelter and transportation and incredible health. Those things didn't magically appear. They were created by individuals within our social species.

You can't make people 'good.' All you can do is be charitable yourself; build, rather than destroy; and use your life to make humanity better in some small way.

How do you convince the guy otherwise?

Convincing people is hard. You can do whatever you want. But I'm going to create.