I'm having trouble understanding who is a defector, who is a cooperator, and who is the joker. The author has copious asides where he asserts "the financial industry; most of the people you work with, and probably you, too" are the defectors. However, I'm having trouble understanding the leap. Clearly he wants to relate this game to an insight about society at large as judged by all of his asides. So I'm trying to understand his position.

In our society most people must perform work to earn money, that money is taxed, to provide public services to all of us regardless of if we work or not. Therefore, the people paying taxes have a cost and get a benefit of the public services which fits his definition: "Cooperators generate a benefit, shared by all, but they pay a cost to do so." If someone pays taxes that must make them a cooperator. Of course we can have shades of cooperation based on how much is paid because no one give all of their money to the IRS. We do have the other extreme where no money is paid.

Now, there are people who pay less taxes or none at all as much or at all can enjoy those same services less cost or no cost all. That's his definition: "[Defectors] sit back and enjoy the group benefit without paying the costs."

In the sliding scale we are all both cooperators and defectors, but to what degree our role alters the equilibrium of the system (ie causing more cooperators or defectors).

That seems pretty straightforward, but he seems have flipped even the definitions: not just the joker/batman role.