When it's okay to be closed-minded

I know I usually harp on about the value of doubt in PoS posts, but this time I look at the cases when it's OK to say, "LA LA LA I'm not listening !". If you doubt everything, you end up learning absolutely nothing.

I personally am never going to conduct any tests to see if the Earth is flat because I know it's round. Uncounted numbers of people have already done tests to prove it's round, the only way to get around (ha ha) this is to say, "they're all lying". If you have so little trust in your fellow human beings that you think this many people are lying, one wonders how you're able to get out of bed every morning. You're not in a healthy state of doubt, you are simply paranoid.

I am not a climate scientist, but I believe global warming is likely mostly the result of humans. I am not a biologist, but I believe vaccines work. I am not a surgeon, but I know surgery works. Nor am I a chemist, but I'm pretty sure dynamite works. And I'm not an electrician but I can still use the internet. Is it dogmatic of me to trust the experts on so many issues about which I'm genuinely no better informed than the average man on the street ? No, because I do understand how the scientific method works.