As was mentioned in the previous post, Reverend Hale advises the accused prisoners to offer false testimonies and confess to witchcraft in order to save their lives. In Salem's court, the only way to avoid being executed for witchcraft is to confess. Throughout the play, Reverend Hale has come to realize that the proceedings of the court are corrupt. When Danforth asks Reverend Hale why he has returned to Salem, Hale replies by saying that he has come to do the Devil's work. Hale proceeds to express his extreme guilt and realizes that he is indirectly responsible for the deaths of innocent citizens. In Act Four, Reverend Hale attempts to influence Elizabeth Proctor to encourage her husband to confess. Hale believes that life is God's most precious gift and is willing to abandon his Christian principles in order to save lives. Therefore, Reverend Hale encourages the accused to confess to witchcraft so that they survive their trial. 

Reverend Hale is visiting the prison and advising the condemned to confess to witchcraft. He is doing this because he is now convinced, after the testimony against Abigail and the accusation of John Proctor, that the people accused of witchcraft are really innocent.

He also knows that under the rules of the court and the way the trials are being held, that anyone who is accused is found guilty and that there is really no way anyone can defend him or herself. So trying to prove innocence is really not an option.

Therefore, he pleads with the condemned to confess, even though they are innocent. He knows this is the only way they can survive, since confessed witches only serve prison sentences and are not hanged.

I think Hale is trying to assuage his own guilt for the part he played in convicting many of the condemned. He is trying to save their lives as a way of atoning for his initial disbelief of their innocence and for allowing himself to be manipulated by Abigail and the other accusers.