In Act 2 of "The Crucible," why does Hale become suspicious of the Proctors?
In Act 2 of "The Crucible," (particularly Scene 3) Hale first approaches the Proctors because Elizabeth's name was mentioned in the court. Then Hale tells the Proctors that, from Parris' records, they have not been to church as often as others. Hale also notes that one of Proctor's sons has not been baptized. (John) Proctor admits this is because he does not "see the light of God" in Parris and refused to have Parris baptize his son.
The really telling moment is when Hale asks John to recite the Ten Commandments. John comes up with all but one: Thou shalt not commit adultery. Hale doesn't know yet that John has committed adultery, but Elizabeth and John do know. And the stage directions describe John's reaction when Elizabeth tells him adultery is the commandment he missed. John looks "as though a secret arrow pained his heart." To this, Hale replies:
Theology, sir, is a fortress; no crack in a fortress may be accounted small.
As events unfold, Hale turns out to be one of the more logical characters. But at this point, he believes that even the smallest sin or misjudgment can or does lead to much more serious sins.
Finally, as Hale is leaving, Elizabeth implores John to tell Hale that the girls have been lying about witchcraft only in order to save themselves from being hanged. As this discussion ensues, Hale asks them if they believe in witches. Elizabeth replies that she cannot and Hale is stunned.