If I have a theory withsome gauge symmetry, I dont understand why we want to fix a gauge. It seems to me to be 1. artificial 2. ignoring a real symmetry of the equations For example in electromagnetism, we can use the lorentz gauge, but why would I? It removes a degree of freedom that should be there and in its place puts in a constraint that has no basis in the physics of the system. Edit: to emphasize this, if we choose the Lorentz gauge, aren't we throwing out all cases that don't satisfy that constraint? What happens to those cases?