  Over the last decade optical spectroscopic surveys have characterized the low
redshift galaxy population and uncovered populations of star-forming galaxies
back to z ~ 7. This work has shown that the primary epoch of galaxy building
and black hole growth occurs at redshifts of 2 to 3. The establishment of the
concordance LCDM cosmology shifted the focus of galaxy population studies from
constraining cosmological parameters to characterizing the processes which
regulate the formation and evolution of galaxies.In the next decade, high
redshift observers will attempt to formulate a coherent evolutionary picture
connecting galaxies in the high redshift Universe to galaxies today. In order
to link galaxy populations at different redshifts, we must not only
characterize their evolution in a systematic way, we must establish which
physical processes are responsible for it. Considerable progress has already
been made in understanding how galaxies evolved from z ~ 1 to the present day.
Large spectroscopic surveys in the near infrared are required to push these
studies back towards the main epoch of galaxy building. Only then will we
understand the full story of the formation of L* galaxies like our own Milky
Way. A large near-IR spectroscopic survey will also provide the calibration
needed to avoid systematics in the large photometric programs proposed to study
the nature of dark matter and dark energy. We provide an outline design for a
multi-object 0.4 to 1.8 micron spectrograph, which could be placed on an
existing telescope, and which would allow a full characterization of the galaxy
population out to z ~ 2. We strongly recommend a serious further study to
design a real instrument, which will be required for galaxy formation studies
to advance to the next frontier.
