  We propose that the flavor structure of the standard model is based on a
horizontal $SU(2)$ symmetry. It generically predicts (i) a parametrically small
mass for the lightest charged fermions, (ii) small mixings in the quark sector,
and (iii) suppression of flavor-changing neutral currents. Supplemented with
the assumption of a strong hierarchy between the second- and third- generation
masses, it also predicts (iv) a large $CP$-violating phase in the quark sector.
Only Majorana neutrinos allow for large mixings in the lepton sector. In this
case, this framework further predicts (v) near-maximal $\theta_{23}^l$, (vi) a
normal hierarchy of neutrino masses, and (vii) large $CP$ violation in the
lepton sector.
