System Thinking<span> is the art and science of making reliable inferences about behavior by developing an increasingly deep understanding of underlying structure. Its related to side effects because the behavior interferes with the side effects depending on it's structure. </span>
In lines 29-34 Shylock gives his reason.
"Yes, to smell pork; to eat of the habitation which your prophet, the Nazarrite, conjured the devil onto! I will buy with you, sell with you talk with you, walk with you and so following; but I will not eat with you, nor pray with you."
Shylock's reasons are to do with his own religious beliefs.