  Digital identity seems like a prerequisite for digital democracy: how can we
ensure "one person, one vote" online without identifying voters? But digital
identity solutions - ID checking, biometrics, self-sovereign identity, and
trust networks - all present flaws, leaving users vulnerable to exclusion,
identity loss or theft, and coercion. These flaws may be insurmountable because
digital identity is a cart pulling the horse. We cannot achieve digital
identity secure enough for the weight of digital democracy, until we build it
on a solid foundation of "digital personhood." While identity is about
distinguishing one person from another through attributes or affiliations,
personhood is about giving all real people inalienable digital participation
rights independent of identity, including protection against erosion of their
democratic rights through identity loss, theft, coercion, or fakery.
  We explore and analyze alternative approaches to "proof of personhood" that
may provide this missing foundation. Pseudonym parties marry the transparency
of periodic physical-world events with the power of digital tokens between
events. These tokens represent limited-term but renewable claims usable for
purposes such as online voting or liquid democracy, sampled juries or
deliberative polls, abuse-resistant social communication, or minting universal
basic income in a permissionless cryptocurrency. Enhancing pseudonym parties to
provide participants a moment of enforced physical security and privacy can
address coercion and vote-buying risks that plague today's E-voting systems. We
also examine other proposed approaches to proof of personhood, some of which
offer conveniences such as all-online participation. These alternatives
currently fall short of satisfying all the key digital personhood goals,
unfortunately, but offer valuable insights into the challenges we face.
