In Act 3, Proctor and Mary Warren come to the court to tell the truth about the presence of witchcraft. May Warren tells Danforth and the others that it was all "pretense." In other words, she admits that the girls were lying about the presence of witchcraft. Everything was an act. However, Danforth (and Hathorne) are reluctant to let the court be challenged. They are stubborn in this respect. Even after Mary's admission, Danforth says "I have until this moment not the slightest reason to suspect that the children may be deceiving me." He says this even though Mary has given him a reason.
Danforth tells Proctor, " I judge you not, sir. I am ready to hear your evidence." But Danforth already has his mind made up. He hears Mary's and John's evidence and makes his own conclusions. He and Hathorne have embraced a policy of guilty until proven innocent but with little hope of proving such innocence. They are practicing the very definition of prejudice.
In Act 4, when Parris warns Danforth that the rebellion in Andover might spill over and incite a rebellion in Salem, Danforth denies the possibility. In fact, he denies that there is still a problem in Andover. He says, "Andover is remedied. The court returns there on Friday, and will resume examinations." He is in denial or he is simply lying in order to discourage the idea of rebellion in Salem.