This was my philosophy for a long time. The fact of someone believing something is evidence. It's not evidence necessarily that the thing they believe is true; it may not say anything about the thing they believe; but it is evidence about their mind and about the events in the world that affected their mind. Belief is a cognitive event; it isn't outside of cause-and-effect.
This was my philosophy for a long time.
Past-tense?
In Techniques of the Selling Writer, Dwight W. Swain gives advice on receiving advice:
One way to reduce damage done by cached thoughts is to cultivate a habit of asking questions about the origin of the thought. Do you remember where you heard the thought? Did it come from someone practicing good epistemic hygiene, or do they just unthinkingly pass on anything they hear? If somebody offered advice based on their own experiences, how representative is their experience? What kinds of experiences have they had that prompted that advice? Are there alternative ways of interpreting those experiences? Or if you're the one offering advice, which you came up with yourself, what situation led you to come up with it? How generalizable is it?
So far I have mostly been framing this as a way to notice flaws in seemingly good advice. But there's also an opposite angle: finding gems in seemingly worthless information.
All outcomes are correlated with causes; most statements are evidence of something. Michael Vassar once gave the example of a tribe of people who thought that faeries existed, lived in a nearby forest, and you could see them once you became old enough. It later turned out that the tribe had a hereditary eye disease which caused them to see things from the corners of their eyes once they got old. The tribe's theory of what was going on was wrong, but it was still based on some true data about the real world. A scientifically minded person could have figured out what was going on, by being sufficiently curious about the data that generated that belief.
Some people tend to stop reading a text whenever they come across blatantly incorrect statements. I mind much less. Yes, the person may be generally mistaken, but they may still have some worthwhile points mixed in. Folk theories can be useful, even when they're entirely wrong. What you're reading is somebody's interpretation of an event, which provides information about the event even if the interpretation is wrong. Can you come up with a better interpretation?
Maybe you disagree with something that I've said here? In that case, what data do you think generated this advice? What conclusions would you derive instead?