The OP kind of moves toward the conclusion, but doesn't really reach it. Etiquette and an open mind are necessary but not sufficient conditions to convincing someone.<p>Far more effective is realizing that the arguments that may convince you (in the case of the manifesto, perhaps, appeals to natural justice / rights), may not be the arguments that work for someone else.<p>In the equal marriage debate in Ireland for example (a pretty conservative country, most would agree), campaigners tried for years to talk about 'social justice' but there was a portion of the population (largely older people) who were just not convinced.<p>What that population needed to hear was a) a message from someone that was like them, and b) an argument couched in terms of the impact that the marriage vote would have on their grandchildren.<p>That was far more effective and the country ended up voting for equal marriage. The result of the referendum was also much more legitimate - it wasn't a case of one social class / group pushing through a desired outcome. It genuinely came from the whole country, even though different groups voted for different reasons.<p>Likewise, if someone believes that all affirmative action schemes are inherently wrong-headed, no amount of argument that "the outcome of affirmative action can be good in the long run" is going to sway them. Second guessing their motives and saying "you're just trying to protect your own interest" is a good way of ensuring they never listen to you again.<p>It takes guts to admit that not only is your argument potentially not convincing to someone, but that you also may be the wrong person to be making it. In this vein, you can, as a result, also spend a long time with someone and still end up talking past them if you're not careful.