This is certainly an incredibly relevant concept for you to explore and think through as you re-read this amazing play. A key theme that is well worth investigating in relation to each character is how they regard "the truth". It is clear that the majority of the populace, in the way that they at least tacitly if not openly support the Salem witch trials, hold personal integrity and truth at a very low level. These characters range of course from the Putnams, whose outright abuse and manipulation of the truth is exploited for financial and personal gain, to characters such as Giles Corey, Rebecca Nurse and, eventually, John Proctor, who all die in their own way as part of an act of resistance against the lies of the Salem Witch Trials.
For me, however, by far the most interesting character to study in relation to the truth as a concept is Elizabeth Proctor. Consider the rock and a hard place that she is placed between when she lies to supposedly save her husband, but also think about the way that when Hale tries to persuade her to encourage her husband to lie to save his life, she calmly and quietly rejects this proposal as "the Devil's argument". She is very clearly a round character whose relationship with "the truth" would make a good essay topic.
I think that you have to discuss how "truth" is seen in specific characters' actions. For example, how do characters like John Proctor and Giles Corey view truth? It is in this vein that you would be able to examine how specific plot elements fit into this configuration. Due to the fact that you are looking at how truth is being articulated throughout the play, you have to look at how individual characters behave and break down the elements of literature in these settings. Another example would be to examine how Elizabeth lies in court to protect her husband, and analyzing the setting and plot at this moment in the trial might be good in terms of expressing how deception can fit into the larger scope of truth. Addressing the First Act would be an instance of how individuals deceive in the hope of others accepting it as truth.
For me, the concept of truth has very little role in the play up until the last act. For most of the play, the truth is simply something that can be ignored when the people who have power wish to ignore it.
In Act IV, however, the truth comes to play a larger role, particularly with John Proctor and his decision about whether to tell the truth and die or lie and live.
At this point, the truth becomes something that can truly set Proctor free. By telling the truth, he frees himself from the doubts he has had about his basic goodness and morality.
This is one of those plays that shows the contrast of a concept to lead you as a reader to a conclusion. The conclusion we should reach by the end of The Crucible is that the terrible lies stated by the group of girls, particularly Abigail resulted in the truth not being believed. When lies are rampant, it is harder to find the truth.
The court should have in this case stood for truth. However, it didn't. The court believed lies and punished the truth of John Proctor's testimony. This is unfortunate and innocent people lost their lives because of it, that's what made this play so powerful.
When I think about the concept of truth in the play "The Crucible" I have to look at two things; what were the Puritan beliefs, and what truths were evident?
The Puritans had no scientific evidence or medical knowledge to enable them to think of the world they lived in as anything other than based on good and evil. Things they understood were good and all else was evil. In the beginning I think that Danforth and Paris brought Reverend Hale in because they wanted the truth. However, once Hale tried to define the truth to them, Danforth no longer wanted to hear it. Instead, he was in a position where he had political power. He tried to twist the truth buy forcing people to confess to lies.
Danforth lost focus of the truth and goodness through his own ambitions and less because of his Puritan beliefs. John Proctor found his own personal redemption through embracing the truth despite it meaning his life would end.