  We present a unifying framework encompassing many social choice settings.
Viewing each social choice setting as voting in a suitable metric space, we
consider a general model of social choice over metric spaces, in
which---similarly to the spatial model of elections---each voter specifies an
ideal element of the metric space. The ideal element functions as a vote, where
each voter prefers elements that are closer to her ideal element. But it also
functions as a proposal, thus making all participants equal not only as voters
but also as proposers. We consider Condorcet aggregation and a continuum of
solution concepts, ranging from minimizing the sum of distances to minimizing
the maximum distance.
  We study applications of the abstract model to various social choice
settings, including single-winner elections, committee elections, participatory
budgeting, and participatory legislation. For each setting, we compare each
solution concept to known voting rules and study various properties of the
resulting voting rules. Our framework provides expressive aggregation for a
broad range of social choice settings while remaining simple for voters, and
may enable a unified and integrated implementation for all these settings, as
well as unified extensions such as sybil-resiliency, proxy voting, and
deliberative decision making.
