To make people question some of their deeply-rooted biases, no amount of speeches or hurling of facts and proofs at them can pay off at times. A better way to go about it might be to first appeal to their biases, and slowly start chipping it away from within. Filmmaker Dijo Jose Antony and screenwriter Sharis Mohammed go by this maxim in the film Jana Gana Mana.
In quite an interesting se-up, at the interval point, they get the audience to cheer for encounter killings — which is unfortunately quite popular in our society too — only to spend the next half showing why that whole idea is wrong. But, at least in cinema, people would like the rug being pulled from beneath their feet, which is why many ended up cheering both for the idea and the dismantling of it.