In The Crucible, Proctor confesses to witchcraft... but was he just doing it, or actually being truthful about it? I also would like some evidence, no matter which way the answer falls..
Proctor was not using witchcraft. There is no passage in the play that suggests he was. True, he tells Danforth that he will confess to the charges against him, but that is only an attempt to save his life. This false confession is really an attempt to dismiss the power of the court. Danforth and Parris have no moral authority, and so no real authority at all.
Confessing to them doesn't quite count as lying because they are forcing the lie on him.
Proctor was not an instrument of the Devil, the people holding the witch trials were. That goes for everyone involved. Proctor found himself in a period of madness. Everyone around him was acting crazy. He confessed to save himself. There was no sane option. He was not actually involved in witchcraft. None of them were.
Proctor only confesses, momentarily, to save his life. He knows that if he does not confess, he will be hanged. If he does confess, however, Danforth and the other leader will accept him as a good example for the rest of the village and will allow him to go home.
When Proctor discovers that his verbal confession is not enough- that his signature along with a list of the names of all the others accused will be posted on the courthouse door- he takes his confession back. This shows that he truly cannot live with a lie. He has not been working with the devil and only confessed initially because he believed it was worth it to save his life. When they want him to post his name for all to see, he knows that the truth is more important and he tears up the confession.