Well for startes my wife told me she changed shifts with a coworker, so she had this day of, and was at work yesterday.
I never heard this conversation, so I have no evidence of it, but I generally accept her statements on faith.
The general principle of accepting her statements is based on experience, but each specific instance is unique and without evidence.
If she came home and said she had had tea with the queen, I wouldn't accept it first hand for example, since this seems quite unreasonable.
I generally accept experts statements on their area of expertise on faith. If I find the statements unreasonable in my own experience, I tend to be more sceptic than when it confirms my other experiences.
I also believe that there are no invisible soundless flying mice in the room with me now. This is not based on any evidence at all.
I also believe that there are no 10 by 10 by 10 meter objects made of swiss cheese in orbit around pluto. Again purely on blind faith.
/Soren