You can definitely enforce non-zero sum contracts, the problem being whether they are actually useful. If you're handing out loans, nothing stops the borrower f

You can definitely enforce non-zero sum contracts, the problem being whether they are actually useful. If you're handing out loans, nothing stops the borrower from vanishing and creating a new identity or otherwise resetting their 'credit score'. It seems like a solvable problem though, you could then depend on some identity or credit oracle, and that could be built on trust (eg. in a government or facebook id), or some meaningful reputation scheme. I guess the trick here is whether you consider "losing credit score if you don't re-pay" enforcing the contract or not. Doing anything stricter, like programmatically garnishing wages or handling bankruptcy, seems like it would require a hard 1:1 mapping between a person and their ethereum presence, which is much more than trusting an oracle to provide a unique ID or reputation based credit score.