There's nothing wrong with differences of opinion, to take an example from my native Australia, the greatest rivalry amongst car fans was Holden versus Ford. I remember 29 years ago, a Holden dealer had an advertisement where they'd bought a new Ford and the dealer cheekily said that you could come and test drive the new model Ford and he wouldn't try to sell it to you. Ford got annoyed, but on the flip side of the coin, someone who wasn't sure whether they wanted a Holden or a Ford might test drive the Holden, and then say, "Okay, now, I'll try the Ford," and after that, say to the dealer, "Thanks, I like the Ford better." The dealer might have said, "What do you like better about it?" or rung you up a few days later and said, "Are you sure you haven't changed your mind?" Two people might go through and one says, "Nah, the Ford's a heap of junk. I'll buy a Holden." Another might say, "No, I like the Ford better." And neither of them are wrong.

When someone forms an opinion based upon misinformation, as much as you might want to, you don't have an obligation to change their mind, unless, of course, it can only end in tears. I mean, if someone told me that they wouldn't get their kids vaccinated because they could turn out autistic, I would tell them that it's crap, and that Wakefield's "hypothesis" has been debunked numerous times.

But here's the thing to remember. Many people form opinions and later wish that they had chosen the opposite path.