Why does science disregard mere opinions and anecdotal sayings?

Answer 1

Science is the process of determining that which can be known about the natural world.

Anecdote and opinion are not disregarded, but are, rather, treated as precisely what they are, narrative stories and personal observations or beliefs.

Because human beings are capable of creating fiction, and because human beings are relatively poor and biased observers, ALL observational claims and all narrative stories must be treated skeptically as potentially fictitious, or erroneous.
Even a theory is nothing more than an opinion, and as such, must be suspect of error or bias.

Science subjects all ideas, anecdotes and opinions to verification.
That is, it does not matter what you claim to be reliably true.. science demands that you must be able to Demonstrate that it is reliably, replicably true.

Also, sincerity has no bearing on science. all delusions seem real to the deluded... You can be absolutely convinced that you saw a ghost, but if you can not demonstrate to anyone else unequivocal evidence of a ghost, then you have no way of proving that your experience was not entirely in your own head.

Science treats even the grandest hypothesis as if it is no better than opinion.
Science even treats experimental results as being no better than anecdote.

All ideas are subject to falsifiability...
All results are verified thru other scientists repeating your experiments to determine if your observations can be trusted to be accurate.


Only when theory has been repeatedly proven to predict observation, only when repeated experimentation has consistently provided the same results does science invest any claim with provisional acceptance.