Or that morality isn't absolute. Society's perception of morality shifts over time which is a part of what drives the changing of laws. If you accept this thoug

Or that morality isn't absolute. Society's perception of morality shifts over time which is a part of what drives the changing of laws. If you accept this though then that means a shifting of agreed upon morality is a part of the system and what is normal today may be distasteful tomorrow and despicable in a decade. This isn't exclusive to laws though anyhow. If you believe morality can be better tomorrow than today then you have to accept either being immoral today or only relatively moral to your own time.