Most people will concede that the first statement is more true then the second statement, and you can work from there to a general principal.
That will only work if the person has no emotional attachments to his current beliefs.
Basically, you have to understand why people accept certain ideas. In the case of cultural relativism, the reason people accept it is because a lot of cultural and social behaviors and beliefs are in fact very relative, and have more to do with how someone was raised then with any sort of objective reality.
No. People might accept cultural relativism because all their friends think that cultural relativism is cool.
I tend to find that people are instinctively paranoid about that line of approach, though, since "you'll be happier if you believe X" is a line of attack usually taken by religions, cults, and other hostile memes.
It a line of attack being used by religions because it works for certain people. If you want to convince the kind of person who is religious because he believes the promise that being religious leads to a happy life, than you have to play on that level.
And, of course, most people don't think that their beliefs are irrational.
I think it's fairly straightforward to find a minor irrational belief of someone else that's irrational and where changing that belief would make the person more happy. It's just a matter of being flexible enough to understand where another person is coming from, understanding the challenges they face in life and understanding which beliefs hold the person back.
Convincing a person who believes that they are worth nothing that, this is an irrational belief isn't that hard. Changing the belief is a bit more difficult but most people have plenty of beliefs that they don't like to have.
That will only work if the person has no emotional attachments to his current beliefs.
That's why it's important to acknowledge that the idea they are using is useful in some situations, just not in others. It's a way to "leave them a path of retreat", a way for them to take a step back and not totally "lose" a belief they found useful and effective (and that they have an attachment to), but to realize that it's just not useful in all situations.
...No. People might accept cultural relativism because all their friends think that cult
I'm afraid I haven't properly designed the Muggles Studies course I introduced at my local Harry Potter fan club. Last Sunday we finally had our second class (after wasted months of insistence and delays), and I introduced some very basic descriptions of common biases, while of course emphasizing the need to detect them in ourselves before trying to detect them in other people. At some point, which I didn't completely notice, the discussion changed from an explanation of the attribution bias into a series of multicultural examples in favor of moral relativity. I honestly don't know how that happened, but as more and more attendants voiced their comments, I started to fear someone would irreversibly damage the lessons I was trying to teach. They basically stopped short of calling the scientific method a cultural construct, at which point I'm sure I would have snapped. I don't know what to make of this. Some part of me tries to encourage me and make me put more effort into showing these people the need for more reductionism in their worldview, but another part of me just wants to give them up as hopeless postmodernists. What should I do?