  I argue that it would be crucial to have as many channels as possible to
understand the physics of electroweak symmetry breaking (EWSB) in
next-generation collider experiments. A historic example of the parity
violation and the $V-A$ interaction is used to make this point. An e^- e^-
option offers us a new channel in this respect. The usefulness of this channel
is exemplified for the case of supersymmetry and of the strongly coupled EWSB
sector.
