You have to start from some sort of agreed base, which is a fact (not an opinion).
No. You have to start from first principles, as far as you can. That involves questioning whatever can be questioned as far as possible.
Let's take the example of pointing the laser at the moon. Forget what anyone else tells you. What is actually demonstrated by it? Does it demonstrate that Neil and his mates landed on the Moon in 1969 and left it there?
Well, what is it?
It is a glint of light coming from the direction of the moon.
Does it happen every time you point the laser?
Yes. Ergo, it appears to be in response to the pointing of the laser.
What would cause the glint?
Some sort of reflective object.
Is it possible that there would be a glint of light in response to a laser if there was no reflective object stopping the laser?
No.
Is it possible that it could be a natural object?
Not to my knowledge.
Is it possible that someone placed it there?
Yes.
Is it possible that someone other than Neil and his mates placed it there, or that it was placed there at some other point than in 1969?
Yes.
Is there any evidence that it was placed there in 1969?
Well, at this point, I am told there is, but I haven't seen it.
So, until I do see it, it remains an open question.
That's how critical thinking works. You have to evaluate what you are told, as far as possible. Sometimes there is no certain answer because you don't have access to all the information.