Read the argument carefully and identify the moral premise on which it is based. For example, in the argument that "the death penalty is a crime against humanity" uncover the notion that it is against moral code for one person to kill another person.
Examine the moral premise and assess its validity in general and degree of dominance in this particular case. Make a list of situations where the moral premise is valid and invalid. For example, a premise that killing is against moral code might be invalid if you had to kill someone for the dominant reason of defending yourself, another person or your country in war.
Evaluate the specificity of the moral argument. Assess how clearly the writer is connecting his moral premise to a particular issue. For example, judge the statement, "Lying is dishonest and thus morally incorrect," as a weak moral argument because it doesn't specify if lying is always or sometimes morally incorrect and what the exceptions might be.
Assess the effectiveness of all the supporting evidence defending the moral argument. Look for strong evidence that convinces you or illuminates sides of an issue you're not familiar with and weak evidence that can be refuted with obvious counter arguments.