  The competition between CDM and MOND to account for the `missing mass'
phenomena is asymmetric. MOND has clearly demonstrated that a characteristic
acceleration $a_0$ underlies the data and understanding what gives rise to
$a_0$ is an important task. The reason for MOND's success may lie in either the
details of galaxy formation, or an advance in fundamental physics that reduces
to MOND in a suitable limit. CDM has enjoyed great success on large scales. The
theory cannot be definitively tested on small scales until galaxy formation has
been understood because baryons either are, or possibly have been, dominant in
all small-scale objects. MOND's predictive power is seriously undermined by its
isolation from the rest of physics. In view of this isolation, the way forward
is probably to treat CDM as an established theory to be used alongside
relativity and electromagnetism in efforts to understand the formation and
evolution of galaxies.
