Groups change their minds one person at a time. Win the conversations, not the crowd.

Crowds do not think, they react. The actual changing of minds happens in ones and twos, usually away from the meeting. Trying to convert a room in public makes everybody defend their position in front of witnesses, which is the worst possible condition for reconsidering anything. Quiet conversations have no audience to lose face in front of.

Pick the two or three people whose view would bring others with it, and talk to each of them separately. Ask more than you argue. By the time the group discusses it, most of the work is already done.