The skeptical hypothesis argument and the argument from moral disagreement each provide a way to establish that moral beliefs require a certain kind of justification.

Conversely, one crucial premise in the regress argument claims that no moral belief can be justified non-inferentially. Another crucial premise, (8), claims that an inference cannot justify its conclusion unless its premises are justified. These premises claim, in effect, that a moral belief needs a certain kind of justification. One way to establish this need is to point to a contrary possibility that is not yet ruled out. That is what the skeptical hypothesis argument does. Another way to conf