According to Wikipedia:
A closed system is a physical system that does not allow certain types of transfers (such as transfer of mass and energy transfer) in or out of the system.
According to my textbook, the principle of conservation of charge is:
The algebraic sum of all the electric charges in any closed system is constant.
Isn't this circular logic? In terms of charge, a "closed system" is one in which charge can neither exit nor enter. If the charge neither exits nor enters, then of course the sum thereof stays constant.
Or is the principle saying that the only way for the sum of charge in a system to change is via transfer of charge in or out of the system? (In this case, wouldn't it make more sense to state the principle as "charge can neither be created nor destroyed"?)