I wonder...

Have any of you changed your minds dramatically on an issue? I'm not talking about a one-time choice, like in deciding to have the fish instead of the chicken at a restaurant. I'm talking about a big societal issue with a pro and anti side. If so, I'd like to know the process by which this issue shifted in your mind. Tell me how adamant you were about the issue before you changed your stance, what caused you to reevaluate your previous stance, your current stance on the issue and how adamant you are about your current stance.

EDIT: Question also asked over at thequestionclub here.