Why Does Socrates claim that no person ever desires what is bad?
The arguments to support the claim that Socrates believes that no man ever desires what is bad may be found in the Meno. In this conversation, Socrates and his fellow man Meno are in search of true knowledge (or the form) of virtue. As their discussion follows that winding convoluted path that is common to Socratic debate, Socrates exposes a feasible argument regarding basic human nature.
Meno makes a claim that virtue is desire for what is good or beautiful. Beauty is used in a much broader sense that as we have come to know it. Beauty is used to describe not only what is pleasing to the eye, but what is also pleasing to the soul and hence our very being. According to Socrates, it follows that if beauty is always desired no person could desire what is bad. It is through this individual perception that every person believes his or her choices to be good. Therefore it is impossible to desire what is bad (at least in the individual's eye). Socrates tempers his broad claim by stating that men desire only self-good which may not be virtuous. At this point in the Meno, they continue in search of the form of virtue since the claim that the desire for what is good is virtue is not sufficient.
By following this logic presented to us, an act that is punishable by law in our society can be shown to be good in the perpetrator's eyes. For example, let's examine a bank robbery. The robber, in premeditation, perceives money to be beautiful, and therefore good. He desires to have more of it, which from his reference is a good thing. This means that the robber, through the acquisition of more money, can justify the robbery as good. It is easy to see how this can apply to any situation, which is to say that no person desires what is bad.