Privacy, specification, and custody in a clearinghouse for interdependent action. Three design dials, one result: the welfare-maximizing clearinghouse holds no principal, fixes terms late, and discloses progress only through a k-anonymized aggregate.
What happened to everyone who took the threshold mechanic — “this happens only if enough of us commit” — to market across 20 years: PledgeBank, ThePoint/Groupon, Tilt, Kickstarter, and the rest — who survived, who died, and why.