How is the theme, "Do unto others as you would have them do unto you" developed in The Merchant of Venice? Give examples that show when it is used positively (for the good) and when it is used negatively (bad).
The Merchant of Venice is a perfect example of man's ultimate selfishness but it also reveals man's capacity for compassion. Shylock and Antonio are both guilty of considering only their own perspective and not worrying about how they affect others. Shylock is also intent on "doing to others as you would have them do unto you" and does not try to hide the fact. He even stresses that Antonio only has himself to blame and Shylock "will feed fat the ancient grudge I bear him. He hates our sacred nation." (I.iii.42-43) Shylock is so incited by thoughts of Antonio and his self-serving ways that he vows to exact his revenge based on what he claims to have learnt from Antonio's example :" The villainy you teach me, I will execute." (III.i.61) Whilst his unhealthy need for revenge is to be discouraged, and which Portia tries to moderate, Shylock is, at least, transparent enough that each character knows where they stand with him.
Antonio on the other hand, will have others believe in his kindness and he is very caring and accommodating towards his friends. He is more than happy to help Bassanio to win Portia's hand in marriage, even if he must deal with the much-despised Shylock. At one stage, he even accepts his fate as it seems that justice can only be served by delivering his "pound of flesh." However, it is Antonio who has "disgraced me (Shylock), and hindered me half a million; ... cooled my friends, heated mine enemies; and what's his reason? I am a Jew..." (III.i.47-50) Antonio is therefore a hypocrite. His appearances are deceiving.
At the end, when Shylock has been tricked out of his bond, Antonio relishes Shylock's pain and inflicts the ultimate insult by insisting that Shylock convert to Christianity. Antonio is ensuring that he will do to Shylock what Shylock attempted to do to Antonio - ridicule him,ruin him,defeat him or even kill him if he had taken his "pound of flesh." Antonio cannot see that he has contributed to the man Shylock has become. He wants to "do unto others..." against Shylock but, other than accepting the hands of justice which would have given Shylock what he wanted, cannot see Shylock's right, if he must apply Antonio's philosophy, to do the same unto him. Antonio does not think he deserves Shylock's scorn.
Portia is the one who tries to reason and can see the damaging effects of Shylock's and Antonio's hatred. She tries to reason with Shylock and wants to persuade him that mercy "blesseth him that gives and him that takes," (IV.i.182) which is exactly what is supposed to happen when a person "does unto others..." That person will have his blessings bestowed right back on him. By the same token, she holds him to his bond when things change and will not let him merely take his money. She measures justice and fairness, something neither Shylock nor Antonio do.
Hence the theme of justice versus mercy, of values and prejudices is developed by revealing both ends of the spectrum and how some people (Antonio) contribute to the dire situation without even realizing it or without accepting any responsibility. There is no humility in either Antonio or Shylock both of whom reveal an arrogance that serves no purpose. Just as Shylock is "an inhuman wretch, Uncapable of pity"(IV.i.4-5), Antonio is prejudiced based on the fact that Shylock is a Jew.