Two words; “Giant Squid”.
Until September 30, 2004 all we had for Giant Squid was ‘anecdotal evidence.’ Tall stories from sailors? Sceptics like me regarded Giant Squid in much the same light as the Loch Ness Monster. We were wrong… Now to call something “anecdotal evidence” is usually considered enough to dismiss it, but vast amounts of our science are based upon “anecdotal evidence” in the sense it is often employed.
Imagine the state of Anthropology or Geography (pre-20th century) or our knowledge of Natural Science if all observer reports were immediately binned as worthless. Vast amounts of our learning and scientific knowledge is based upon observation – empiricism. Sure we can rationally test a hypothesis, and we can conduct experimental studies, but that is not how most knowledge was originated. If I say the sun comes up, it’s “anecdotal evidence” – but you can test it easily.
If I say Denmark exists, it may be harder, but you can still hope to observe it. If I mention I saw a rare moth and you had believed the moth to be extinct, you must weigh my abilities as an observer, for it may be unlikely you can repeat the experience. Now we all know as I frequently point out, that witness testimony is unreliable. However any scientific experiment is based upon witnesses conducting the experiment and observing it (and then interpreting and writing up their results and conclusions).
Hence we get various well known experimental errors. In law cases, we know the witness of eyewitnesses is unreliable – but that is not what anecdotal means in that sense. Anecdotal evidence in law is hearsay, without direct experience. Now I once, in good light with four friends witnesses a “ghost”. I don’t doubt we all saw something that day – I do doubt if it is relevant to the case for life after death. Nonetheless our accounts, and the written testimony recorded independently by us within an hour of the incident is perfect valid empirical evidence, NOT anecdotal.
SO “anecdotal evidence” has been hijacked as a pejorative and extended to a sense it simply does not possess. I may not believe Harry Price’s observers claims of the Hauntings of Borley Rectory to be what they claim, but those observations were not anecdotal. Ditto the descriptions of say The Enfield Poltergeist by the witnesses – possibly unreliable, but NOT anecdotal give a more common example, the medical diagnosis of depression is based upon self-reported symptoms in many cases, which are only experienced by the depressed person – but it is not anecdotal evidence. Saying “I hear Kate is a bit depressed this week, because Felicity mentioned it to Gloria who told me on the bus” – that is anecdotal evidence.