It is in the close of Act II where Proctor makes the argument that it is not justice driving the legal machine of Salem. Instead, Proctor argues that "vengeance" is walking around Salem and making decisions. Proctor's argument is that blind obedience and a lack of skepticism around Salem is empowering those who are manipulating the charge of witchcraft for their own benefit. The entire premise of Elizabeth's arrest is fictitious and Proctor knows this. He understands clearly what it is that Abigail is trying to do and in this, he recognizes that the search for justice is not important in Salem. Rather, it is the fulfillment of vengeance and settling scores through the court system. In this, Proctor recognizes that the law is not being written by those committed to justice, but rater those who are seeking to use the public trust for their own benefit. It is this situation that compels Proctor to action in the closing scene of the act. He seeks to topple Abigail from her exalted perch because of this and, in the process, comes to realize that his hand is being forced by Abigail, who Mary says will blackmail him if he decides to pursue discrediting her. It is here where Proctor becomes convinced that vengeance walks and writes the laws of Salem.