We are often forced to depend on people’s accounts of events we cannot have first-hand knowledge about. The profession of journalism exists to share information about what is happening in other parts of the world. Our legal system depends on eyewitness testimony to determine facts in criminal proceedings. Religious texts relate the experiences of people in support of the existence of a deity.
I have personally attended events that were later reported in newspapers or on television and found significant errors or omissions. My own memory has been proven to be wrong, as I’ve learned when playing back recordings of meetings I’ve attended. Studies have shown that people witnessing the same events have different memories, and those memories were not just shaped by the events themselves but the witnesses’ internal processing of those memories based on other experiences. These considerations make it clear that we should be very careful when using eyewitness testimony to determine the facts of events. And this all assumes that people WANT to report the events accurately (that is, they don’t have an agenda that leads them to intentionally lie).
One way to determine the truth of an event is to find several people who recall the same details, have not collaborated to alter each other’s perceptions, and have no reason to lie. External “physical” evidence should also be available, something which can be checked by anybody. As a general rule, don’t take any one person’s (or group’s) word for something.
The standards should be even higher for events that either support or claim to disprove principles that many people are likely to use in their lives, because the consequences can be very great. Such events include those that prove the existence of a deity, the set of observations that support natural laws that predict how nature behaves and the actions of our leaders.