As a consequence of Hume’s famous is-ought problem, it may seem that no rational justification of a moral statement can ever be inferentially provided, and no argument typically used in applied ethics would ever deserve the title of rational justification. This paper aims to propose a fallibilist, non-foundationalist account of rational justification of a moral standpoint based on rational argumentation. This account will be developed within a noncognitivist theory of morality — a framework that seems to constitute the most challenging context for a similar attempt. First, the paper shows how we can have a good rational justification of a moral claim also if its (necessary) moral premises are neither indubitable nor properly inferentially justified, as long as we adopt what is called a Popperian solution to the “problem of prescriptive basic statements”. Second, it argues that a good rational justification of a moral claim does not need to be deductively valid. Using the idea that implicit presumptions introduced by invalid inferences can be monitored by a number of related critical questions, the article distinguishes between fallacious and non-fallacious invalid arguments, and examines how a use of an invalid non-fallacious argument can count as a rational justification of a moral position in applied ethics. However, applied ethics must do its part, and must be explicitly based on rational argumentation.