The Misuse of Anecdote – a sceptical myth?

On Anecdotes

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.

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About Chris Jensen Romer

I am a profoundly dull, tedious and irritable individual. I have no friends apart from two equally ill mannered cats, and a lunatic kitten. I am a ghosthunter by profession, and professional cat herder. I write stuff and do TV things and play games. It's better than being real I find.
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7 Responses to The Misuse of Anecdote – a sceptical myth?

  1. David says:

    Interesting piece, CJ.
    The ghost sighting you refer to… was that your experience at Thetford Priory? I take it you believe this to be an experience of a ‘residual recording’ type haunting rather than an encounter with a spirit?

    DCG

  2. Mo says:

    There’s a third meaning of “anecdotal evidence”, the statistical one, which (at least in my world) is more commonly used than either of the above. There’s a common reasoning pattern “this happened to me, therefore it reflects a general principle X”. Said principle X would then be dismissed as based on anecdotal evidence, ie. a small number of cases which may not be a representative sample, may embody reporting bias, etc. Virgin Trains are always delayed — how do I know? — because I went on one once, and it was delayed. And the same thing happened to my brother.

  3. Chris says:

    Hi Mo,

    not sure how i missed this before! Yeah this is the mistake of correlation for causality: the common sense adage “correlation is not causality” just reminds us that while things are found together they are not always caused by one another!

    Actually I think this is hard wired in to our brains by evolution – think about it – I eat berries, I get sick. I poke tiger with stick, I get bitten. We make sense of things in “cause and effect scenarios”. Now it could be in both those cases that “correlation is not causality” – the bisonburger we had for lunch was responsible, the tiger just had toothache – but in fact in the majority of cases “correlation IS equal to causality”, and our brains have evolved a cognitive bias towards false positives because poking sleeping tigers and eating berries that made you or your sisters aunties friend sick are high risk strategies, liable to remove you from the gene pool.

    So it’s part of our evolutionary heritage, and a generally useful one – especially in children, who learn this way. Unfortunately it’s not true. But then our brains evolved through adaptive advantage which is designed to aid reproduction and survival, not search out objective truth. So obviously the human brain is simply not designed to know truth! 🙂

    cj x

  4. Mo says:

    obviously the human brain is simply not designed to know truth

    Even so, one might hope that we could have got into the cultural habit of teaching reason to our children, in the same way as we make the effort to teach them non-instinctive moralities that are believed to confer group advantage. But perhaps there’s actually something in the brain that actively rejects it…

  5. Chris says:

    Absolutely. I have all kinds of issues with how we know and what we know – epistemology is my thing, and I spend a huge amount of time on theories of knowledge, but we are evolutionarily disadvantaged form knowing truth, not prevented from doing so. 🙂 Certainly while all our reasoning can be effected by unconscious cognitive biases, I think the quest for rationality is a very noble and important endeavour!

  6. Ashwaria says:

    (1) Evidence in the form of an anecdote or hearsay is called anecdotal if there is doubt about its veracity: the evidence itself is considered untrustworthy or untrue.

    (2) Evidence, which may itself be true and verifiable, used to deduce a conclusion which does not follow from it, usually by generalizing from an insufficient amount of evidence. For example “my grandfather smoked like a chimney and died healthy in a car crash at the age of 99” does not disprove the proposition that “smoking markedly increases the probability of cancer and heart disease at a relatively early age”. In this case, the evidence may itself be true, but does not warrant the conclusion.

    In both cases the conclusion is unreliable; it may not be untrue, but it doesn’t follow from the “evidence”.

    Ancient Mexican Culture

    • Chris says:

      Yes makes perfect sense Ashwaria. No disagreement here. I’ll have to have a look at your link when I get back in!

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