And just demonstrates my point about fact (observed by the person) and explanations - trusting someone's word about what the person has not seen. (see comment about tooth fairy :)

For things you have not observed, you frame all things you hear (and learn from others) within a framework, which dictates how much you trust someone's word to be true. Whether it be your teacher, an authority, a lawyer, a scientist, your parents or your children. It way too easy for conspiracy theorists to continue in their beliefs because they are predisposed to disbelieving what they hear from someone else, since they weren't there themselves to verify its truth.
Everyone who disagrees is lying. Unless you were there, you're either lying or have been deceived. If you were there and disagree, and there's even a slightest reason for you to lie, you're lying. All evidence presented is reinterpreted to fit that axiom. How do you change a conspiracy theorist's mind? They need to trust your word, and an interpretation of the evidence needs to be more plausible to them than their own beliefs.

And you know what? That's exactly the same with good Science. A scientist performs an experiment and documents his findings. What if it can't be (easily) reproduced? Many will decide either to take him at his word, or call him out. Until someone else is able to reproduce and test the results in some manner, the findings may be held in question. And then... if one person is able to verify the results, they're in the same boat. At what point are results trustably accurate? After how many people claim to verify results? If you never do it yourself, you're only always ever trusting someone's word. Of course, most of us would trust scientists' word on experimental matters, so perhaps one or two confirmations would be sufficient. But the only difference between 2 and 200 is ... conspiracy? Mass deception? Extremely complex? Other discoveries and knowledge through history has been upended precisely in the same way - so many people stand by a certain 'fact', and yet in time, one person makes an observation that uproots the entire paradigm.

Ultimately, the only proof we have anything is our own observation. Outside that, we trust others' words and explanations, to whatever degree. Most people we consider 'sane' will have a lower threshold for 3rd party verification. :)

We each make judgement calls based on our own experiences. Critical thinking challenges the norm, looks deeper at what we know in an attempt to verify as best we can for ourselves what it is we think we know. Critical thinking is good - as long as it doesn't turn into paranoia, rampant disbelief of everyone for no reason other than "I wasn't there to verify so I can't believe you", and conspiracy theories. :P

but anyway...
I'm going to spaaaaaace! (no really, virtually, aboard the next Soyuz launching to the ISS on Nov 6th :) can't stop talking about it, I am excite!)