Shylock is another canny businessman who is unlikely to be irrationally swayed by his emotions in an important usury deal. He is calm, collected and knowledgeable because he knows he is well informed from his contacts upon the Rialto. When dealing with Bassanio and Antonio, Shylock is very cunning and avoids awkward questions whilst keeping the negotiations efficiently short, sharp and to the point. This is emphasised by the short line lengths and quick interchanges at the beginning of scene three. The haggling is not convoluted, though Shylock is wary and deliberative – he never allows his head to give way during important business. With careful management, the Jew believes he can design and create success; a point highlighted by Shylock's retelling a story from the Old Testament. By weighing up the risks and the "peril of the waters" (I, iii, l. 20), he thinks things over carefully and even uses social engineering so as to be sure to glean the most out of Antonio and his desperate companion Bassanio. Shylock contrives and expertly extracts all the money he can get out of Antonio who, in this situation, has to agree to any offer he is given.
When Shylock mentions the pound-of-flesh penalty as "a merry sport" (I, iii, l. 139), it is not clear whether this was intended and planned malice designed as revenge on his Christian nemesis or a light-hearted joke thrown in for the sake of humour. As such, it cannot really be said whether Shylock is allowing himself to be ruled by his head or his heart. I tend to believe that it was more likely to be premeditated and thus, was an action thought about from his head. Still, strong emotions from the heart are prerequisite for someone to want to seek retribution in such a way. If it had been a spontaneous decision on Shylock's part, there would have been more of a case for him following his heart, as it would be a petty way to cozen his bitter rival Antonio for no real economic gain.
Another character with crucial and influential judgements to make is Bassanio. He has already made the decision to travel to Belmont to seek Portia's hand in marriage. This is partially a conscious decision, as marrying into money was a shrewd thing to do and would enhance his social status no end. However, despite the fact she is a woman "richly left" (I, i, l. 160) Portia hold far more attractions for Bassanio. She was probably beautiful and was worthy enough to attract many meritorious and grand suitors. Although he has only met Portia once from a distance, she favourably recollects his visit ("I remember him well" (I, ii,, l. 102)) and it's quite possible that he may be in love with her. Either way, it's an important choice with strong repercussions and Bassanio must have thought about taking out another loan from Antonio very deeply as well as being swayed enough by his feelings to risk everything and venture out to woo Portia.
Portia herself has some knotty decisions to deal with. Her head tells her that the declaration in her father's will be beneficial. Despite being forcefully bound to it and having no choice herself, I think she comes to the conclusion that overall, it will end with a propitious outcome. Portia trusts her father, believes that he will always do what is best for her and, although the rules set down in his will do not very clearly manifest a timeless wish for her felicity, she believes it will be prosperous to obey his wishes. Portia has faith in the three caskets test and thinks that her father has designed it so that only someone really worthy of her, someone who chooses well, could ever become her husband. When she confides in her maid Nerissa, she is more than resigned to having to follow her father's will – she even treats it in a light-hearted and jocular manner, eloquently joking about prospective partners-to-be. Nerissa articulately agrees that it is not necessarily bad thing: she believes in the "Golden Mean" Renaissance philosophy that "it is no mean happiness...to be seated in the mean" (I, iii, l.6-7).
Still Portia confides that her heart does have a say in the matter. Like all girls, she dreams and her heart tells her that she will someday marry for love, not a place in society, and is still waiting for her sweet prince to come. In her conversation with Nerissa, we find that her ideal man is the opposite of all the suitors see has met so far: joyous, modest, generous, interesting and a good communicator. She wants to be the wife of someone noble and have a good relationship, but so far, has been unimpressed and frustrated by her suitors saying "I pray God grant them a fair departure" (ll. 94-5). Portia is wise enough to realise that sometimes the heart will overrule what the rational brain tell her: "The brain my devise laws for the blood, but a hot temper leaps o 'er a cold decree" (I, iii, 15-6). Luckily for Portia, she doesn't face much of a dilemma and is able to carefully balance head and heart in accepting her fate by her father's design.
Later, in the second act, Portia reveals that should anyone want to choose a casket in order to win her hand and fail, they shall never be able to "speak to lady afterward/In way of marriage" (II, i, ll. 41-2). As such, many of her wooers use their heads to weigh up the odds and consider it too big a risk to take. Only those who care enough about her are willing to make such a hazardous plunge again. It is also interesting to see how freely Antonio agrees to Shylock's loan conditions with a complete lack of caution. He is overconfident and one suspects that he would have been more wary and attentive had personal issues not been involved. As it is, he swiftly agrees without even an infinitesimal pause for thought and says, "I'll seal to such a bond," even though Bassanio objects. This is unusually harebrained and unwise for a businessman such as Antonio, again demonstrating how he lets his heart rule his body.
Throughout the play, we can observe conflict within characters between their heads and their hearts. When people rely on just their head, they are successful but often miss out on more subtle sensitivities, whereas always following your heart means imprudent judgements are made and it is foolish at best – especially when people are unable to return or understand your love. As the story progresses, the compromisers tend to come out best as they can balance their brain and their emotions equally.
