“Minds are very hard things to open, and the best way to open the mind is through the heart,” Professor Haidt says. “Our minds were not designed by evolution to discover the truth; they were designed to play social games.”
Thus persuasion may be most effective when built on human interactions. Gay rights were probably advanced largely by the public’s growing awareness of friends and family members who were gay.
A corollary is that the most potent way to win over opponents is to accept that they have legitimate concerns, for that triggers an instinct to reciprocate. As it happens, we have a brilliant exemplar of this style of rhetoric in politics right now — Barack Obama.
Info about a good relevant read: The Effect of In Your Face Political Television on Democracy