The Absence of Proof

I’m back to inviting readers to submit quotations whose origins they want me to try to trace, using my book, The Yale Book of Quotations, and my more recent researches.

James A Smith asked:

“‘Absence of proof is not proof of absence.’ Attributed to William Cowper, as a retort to one who claimed God does not exist because we can’t prove his existence.”

I believe any attribution to William Cowper is anachronistic. The Yale Book of Quotations lists a similar saying under the name of Martin Rees, an English astronomer:

“Absence of evidence is not evidence of absence.”


Quoted in Project Cyclops: A Design Study of a System for Detecting Extraterrestrial Intelligent Life, rev. ed., ed. B. M. Oliver and J. Billingham (1973). An earlier version by A. R. Burn appeared in a book review by Burn in The Classical Review, June 1969: “absence of evidence is not identical with evidence of absence.”

Can any readers of this blog supply earlier versions?

Do any readers have any other quotations whose origins they would like me to attempt to trace?

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  1. BL1Y says:

    Absence of evidence may be evidence of absence, depending on what the subject of the question is.

    For instance, consider the Bright Pink Screaming Elephant That Lives Outside My House. Because the BPSETLOMH is something that we’d expect to create a great deal of evidence, a lack of evidence is evidence that BPSETLOMH does not exist.

    If you believe that were God to exist, he would make his existence known by an abundance of clear, unequivocal evidence, then a lack of evidence is evidence that this type of God does not exist.

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    • BB says:

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    • Don says:

      BL1Y, it would all come down to what you would accept as evidence. Your BPSETLOMH example can only work for a merely physical being that leaves merely physical evidences. You list in your example’s name the evidence you would expect to find: Bright (visual intensity) Pink (visual color) Screaming (audible intensity) Elephant (physical form, if not essence) That-Lives-Outside-My-House (location). The location you give is the most ambiguous of the bunch; most of the known and unknown is universe outside of your house. Unless, of course, your house is bigger on the inside.

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    • Joshua Northey says:

      Well at the very least the statement is not true.

      If you find a ~x it is definitely evidence that x doesn’t exist if you understand anything about epistemology.

      Heck white swans and red firetrucks are (incredibly weak) evidence that “all ravens are black”. Each object you find that is not a “non-black raven” confirms “all ravens are black”, albeit on an infinitesimally small level.

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    • Mike Pone says:

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      • MW says:

        I think you’ve missed the point. On the Bible and modern day miracles, you are not invalidating BL1Y’s argument, you are debating the nature of the required evidence.

        On your statement ‘I think it is very foolish to say, “if God existed, he would do X and make his existence known”': BL1Y has explicitly anticipated this sort of argument – they say “a lack of evidence is evidence that *this* *type* *of* *God* does not exist.” (my emphasis.) You’re saying that God may not be that type of God, which BL1Y has already accepted.

        In summary: BL1Y’s argument is valid, but it is so narrowly drawn that it does not challenge your religious beliefs.

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      • James says:

        But if the Bible is evidence for the existence of God, then by the same logic, the Illiad is likewise evidence for the existence of the Greek pantheon, the Norse Eddas for Odin, Thor, and the Asgard gang, the Bhagavad Gita for the Hindu gods, and so forth.

        Indeed, we can carry the logic to its bitter end, and note that the numerous versions of Star Trek are equally good evidence for the existence of Klingons :-)

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      • Mike Pone says:

        Clearly you need to make a distinction between fiction and non-fiction. We know from the historian Jospehus that Jesus was a real person. We also know that Star Trek is pure fiction.

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      • James says:

        OK, if you’re going to be picky, take as an example the stories told about such well-documented American historical figures as Davy Crockett and Kit Carson. The legends were there, even in their own lifetimes. Carson even writes in his autobiography about being unable to live up to the fictions the authors of the “penny dreadfuls” had written about him.

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      • MIke Pone says:

        @James. So for Davy Crockett and Kit Carson, we have evidence from the same time period that goes against the fiction and myths written in the novels. There exists no such evidence that goes against what is written in the Bible about Jesus. Here we have clear evidence of the son of God without a counter argument from the same time period. So can we use the lack of evidence saying that Jesus was not the son of God as evidence that he was indeed the son of God as written in the New Testament?

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    • nobody.really says:

      [C]onsider the Bright Pink Screaming Elephant That Lives Outside My House.

      “So, you’re worried that a pink dragon will fly over … and fart nerve gas on us?”

      “No,” I said with a nervous chuckle.

      “[Why not?],” Orolo claimed, deadpan. “That’s a sequence of events with a bad end.”

      “But it’s nonsensical. There are no nerve-gas-farting pink dragons.”

      “Fine,” he said, “a blue one then.”

      * * *

      “You could probably talk [uneducated people] into worrying about it. But no, these’ a .. there’s some kind of filter that kicks in….”

      * * *

      “If you worried about pink ones,” [Jesry] pointed out, “you’d have to worry about blue, green, black, spotted and striped ones. And not just nerve-gas farters but bomb droppers and fire belchers.”

      “And not just dragons but worms, giant turtles, lizards…” I added.

      “And not just physical entities but gods, spirits, and so on,” Jesry said. “As soon as you open the door wide enough to admit pink nerve-gas farthing dragons, you have to let in all of those other possibilities as well.”

      “Why not worry about all of them, then?” asked Fraa Orolo.

      * * *

      “There’s no way to get from the point … where we are now, to one that includes pink nerve-gas-farting dragons, following any plausible action principle. Which is just a technical term for there being a coherent story joining one moment to the next…. The mind … knows that there is an action principle that governs how the world evolves from one moment to the next – that restricts our world’s path to the points that tell an internally consistent story. So it focuses its worrying [accordingly].”

      Neal Stephenson, Anatham

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    • DK says:

      BL1Y – you are incorrect.

      You are assuming (1) that a BPSETLOMH would leave lots of evidence and (2) that you are capable of measuring said evidence. There is infinite explanations of why you may have no evidence of a BPSETLOMH. You claiming otherwise is use of an argument from ignorance and is illogical.

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  2. Jim N says:

    I remember reading that in a hard boiled detective story. It was either in Raymond Chandler’s The Big Sleep or it was in a short story in an out-of-print anthology called The Hardboiled Detective.

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  3. JJG says:

    Could you explain where the phrase “In the clutch” came from? As in, the baseball player hit the winning home run, he really came through in the clutch.

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  4. Garson O'Toole says:

    Researcher Stephen Goranson located and shared the following relevant citation on this topic in June 2010. The book scans are in the Google Books database and I have not examined the work on paper. It looks ok.

    The Glacialists’ Magazine v. 3 pt. 3 Dec. 1895, “On the Occurrence of Scandinavian Boulders in England” by Thomas Sheppard, p. 132 :

    Even if no moraine existed, it does not follow that there was no Ice-sheet: it has been remarked by Mr. Dugald Bell that “absence of evidence is not evidence of absence.”

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  5. Eric M. Jones. says:

    “You can take the boy out of the country but can’t take the country out of the boy….” whatever this clever turn of phrase is called. Of course, just because it is catchy doesn’t mean it’s correct.

    It is certainly true that an exhaustive search guarantees that “Absence of evidence IS indeed evidence of absence.” This has been used in math to “solve” for example, the Four Color Problem.

    So “A of B isn’t B of A” is pretty common in language. As regards “absence…” Here’s one (I can see Fred frowning now!)

    The ethics of the Hindus–Susil Kumar Maitra – 1925 ( I hope)
    “…it is not the consciousness of the absence of evil but the absence of the consciousness … ”

    (I suspect that the British ignored everything the Indians wrote for the two-hundred years of their occupation. Google seems to be on it now….).

    ps: Hey Mike Pone: I have a one word proof of the nonexistence of a benevolent God–Neurofibromatosis. By the way…There were no first person writings about Jesus.

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    • MW says:

      ‘I have a one word proof of the nonexistence of a benevolent God–Neurofibromatosis.’

      That would be an example of ‘the problem of evil’. ( Enough has been written on this over the millennia to fill libraries. Let’s not try to recapitulate it all here.

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    • James says:

      “…an exhaustive search guarantees that “Absence of evidence IS indeed evidence of absence.””

      But such an exhaustive search is only possible when the problem domain is finite. The real world (or at least the world of the human imagination) is not finite, so you start with “The gods live on top of that mountain over there” until enough people climb the mountain without seeing the gods. Then the god-folks say “Well, they live in this place that’s just above the sky” ’til the rocket scientists launch a bunch of space probes and they don’t smash against the firmament, and the gods get relocated again.

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  6. Garson O'Toole says:

    Here is an entertaining citation on this general theme. It appeared in a book by the mathematician Augustus De Morgan who is famous for De Morgan’s laws. The words do not follow the precise template of a chiasmus and that impairs its quotability. But De Morgan is one of the most well-known logicians and that raises its noteworthiness:

    Syllabus of a Proposed System of Logic (1860), Page 45. (Google Books full view)
    Failure of proof is not proof of the contrary.

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  7. Steve Tylock says:


    Couldn’t find a better way to answer – you asked for other quotations to trace.

    And my quote memory is bad, but the gist is that a prophet has no respect at home, but is widely accepted in foreign lands. I believe it may be biblical, but am not certain.

    It has application in business – I’m Steve Tylock, local son in the Rochester NY area, but outside of here, I’m Steve Tylock, Author and LinkedIn expert…


    Steven Tylock
    The LinkedIn Personal Trainer

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    • Garson O'Toole says:

      Steve Tylock: You are correct that there is a biblical version of the sentiment you expressed. Here are two instances:

      John 4:44
      King James Bible (Cambridge Ed.) text version from
      For Jesus himself testified, that a prophet hath no honour in his own country.

      Mark 6:4
      King James Bible (Cambridge Ed.) text version from
      But Jesus said unto them, A prophet is not without honour, but in his own country, and among his own kin, and in his own house.

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  8. Ironmistress says:

    This is called in philosophy as “argumentum ad ignoramum” (argument of ignorance), and has been known since the Scholasticists in 12th century.

    The concept “abscence of evidence is not evidence of abscence” is very close to Eastern philiosophical concept of “mu”.

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