In a discussion following one of his posts over at the Chronicles website, Scott Richert notes that politicians, like particles in physics, do not simply have positions. They also have directional velocity. We ignore the latter at our peril.
Continually voting for the politicians who will move us leftward more slowly does not have the consequence of stopping our move leftward. But it does have the consequence of causing us to become more inclined to accept leftward movements as long as they don't happen at too great a velocity. This may leave us with better short-term consequences, but its long-term result is the voluntary corruption of our own moral sense.
That's the whole point of the Hegelian mambo. So forgive me if I sit this dance out.