Murdering people is wrong (at a surface level that requires no moral understanding), because it is illegal (and therefore you'll face consequences from other pe

Murdering people is wrong (at a surface level that requires no moral understanding), because it is illegal (and therefore you'll face consequences from other people), because it is wrong (because it is immoral). There's no circular logic there at all. The second "because it is wrong" is shorthand for more complex moral reasoning that most people don't need to know - who cares if they know it, when the goal is simply to cut down on the murdering?