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Saturday, 14 January 2012

On the nature of evidence

First photo::  direct evidence of erratic transport and displacement :  Conwaybreen, Svalbard
Second photo:  indirect evidence of erratic transport and displacement: Easter Aquhorthies (in the centre, a reddish granite block, probably from Bennachie, a few miles to the west of the site.)  The fact that the large recumbent stone might have been levered up or "adjusted" on the site, or even moved a short distance by the monument builders,  is immaterial to the argument.

Above:  The distribution of the key recumbent stone circles in NE Scotland.
There are reputed to be at least 99 of them.

Erratic transport directions and other glacial features, NE Scotland (BRITICE Project).  Note that erratic occurrences exist at the points of the arrowheads.

On this blog, we have been wasting a vast amount of time recently in trying to elucidate what certain people mean by "evidence".  Without getting too deeply into epistemology, philosophy and the scientific method, and without pondering too deeply as to the meaning of "truth", time to make a few simple points.

In glacial geomorphology, when we are trying to interpret the impact of glaciation on the UK landscape, we are dealing with "circumstantial evidence".  However,  interpretation is informed by direct knowledge of what glaciers do and how they work, in the field, in places like Greenland and Iceland.  I have been to both those places, and have observed glaciers at close hand -- I hope it can therefore be assumed that I know what I am talking about when I form opinions about what has happened in the UK.   If I am right, my evidence will be accepted by my peers.  If I am wrong, one of my peers will come along and falsify my hypothesis through the provision of more reliable circumstantial evidence, well founded in field observations elsewhere, where processes are observable and measurable.  
It is not enough for somebody from another discipline to come along and say "I don't believe you because I don't accept your evidence, or because you have not proved your case."  The burden of proof is then upon him to produce sufficient new evidence, acceptable to the peer group, which will move things to a new conclusion.  
Within the glaciated areas of Britain, the default position must be that large boulders and slabs of rock that might be labelled as "erratics"  -- if found in areas downglacier of source areas -- must be assumed to have been moved by ice, simply because direct observation and direct evidence shows that that is what happens when glaciers flow across a landscape.  There is nothing contentious in that.  (That is true even if such large erratics have been incorporated into man-made monuments, since it seems to be a general rule that the builders of such monuments preferentially used the large stones that were readily to hand, rather than fetching them from a long way off.)  This field evidence is simple, well-established, and not seriously liable to challenge -- and if anybody does wish to make a contentious claim (for example that the large erratic stones have been moved by human beings rather than ice) the burden of proof rests upon him to come up with powerful new evidence.  In the case of NE Scotland, this would mean that he would have to overturn the interpretations incorporated into the BRITICE map and the published field evidence on which those interpretations are founded.

So when I look at large glacial erratics in a landscape which has been repeatedly affected by glacial processes, and call them glacial erratics because that is what my accumulated experience tells me,  I will accept a challenge from another glacial geomorphologist who thinks he or she has better evidence than mine.  But I will not accept a challenge from an archaeologist who knows nothing of glacial geomorphology and who simply says "I do not accept your evidence."   Such a challenge is intellectually dishonest;  it fails to accord me the respect that I deserve as a specialist in this field;  and it is a waste of everybody's time.

By the same token, I am not an archaeologist, and if I wish to say something contentious or to challenge a well-founded hypothesis based on sound direct or indirect evidence, the burden of proof rests upon me to come up with something better, and to marshall my evidence in support of what I am saying.


From Wikipedia

Evidence in its broadest sense includes everything that is used to determine or demonstrate the truth of an assertion. Giving or procuring evidence is the process of using those things that are either (a) presumed to be true, or (b) were themselves proven via evidence, to demonstrate an assertion's truth.  Evidence is the currency by which one fulfills the burden of proof.

Many issues surround evidence, making it the subject of much discussion and disagreement. In addition to its subtlety, evidence plays an important role in many academic disciplines, including science and law, adding to the discourse surrounding it.

An important distinction in the field of evidence is that between circumstantial evidence and direct evidence, or evidence that suggests truth as opposed to evidence that directly proves truth. Many have seen this line to be less-than-clear and significant arguments have arisen over the difference.

Circumstantial evidence directly supports the truth of evidence, from which the truth of the assertion may be inferred. 

Evidence in science

Main article: Scientific evidence
In scientific research evidence is accumulated through observations of phenomena that occur in the natural world, or which are created as experiments in a laboratory or other controlled conditions. Scientific evidence usually goes towards supporting or rejecting a hypothesis.

One must always remember that the burden of proof is on the person making a contentious claim. Within science, this translates to the burden resting on presenters of a paper, in which the presenters argue for their specific findings. This paper is placed before a panel of judges where the presenter must defend the thesis against all challenges.

When evidence is contradictory to predicted expectations, the evidence and the ways of making it are often closely scrutinized (see experimenter's regress) and only at the end of this process is the hypothesis rejected: this can be referred to as 'refutation of the hypothesis'. The rules for evidence used by science are collected systematically in an attempt to avoid the bias inherent to anecdotal evidence.

Burden of proof

Main articles: Legal burden of proof and Philosophic burden of proof
The burden of proof is the burden of providing sufficient evidence to shift a conclusion from an oppositional opinion. Whoever does not carry the burden of proof carries the benefit of assumption. Whoever bears the burden of proof must present sufficient evidence to move the conclusion to their own position. The burden of proof must be fulfilled both by establishing positive evidence and negating oppositional evidence.

There are two primary burden-of-proof considerations:

    • The question of on whom the burden rests.
    • The question of the degree of certitude the proof must support. This depends on both the quantity and quality of evidence and the nature of the point under contention. Some common degrees of certitude include the most probable event, reasonable doubt, and beyond the shadow of a doubt.
Conclusions (from evidence) may be subject to criticism from a perceived failure to fulfill the burden of proof.

See also:

See also:
The Burden of Proof


chris johnson said...

This is a great topic.

In my day job I help companies decide on marketing direction for new technology. The parallel with the late neolithic and Stonehenge is that we always have to make choices based on insufficient evidence - perhaps why I find this blog and the subject so fascinating.

One issue with the Stonehenge discussion is that the economic consequences of pursuing the wrong line are limited to the next subsidy, so experts are able to waffle along for long periods riding their hobby horse. In business it is different; make the wrong choice and it might cost you hundreds of millions, or like Kodak send your company over the cliff.

The method I use is "rational plausibility". This is scientific because you seek evidence where it exists and you test your hypothesis before committing large amounts of money and time. When you can see that something worked in situation A then this is an important data point for assessing whether it might work in situation B - something Brian might not agree with, although I expect we see no reason why glaciers in Iceland might behave differently to glaciers in Wales.

So the real issue here, when you want to move the debate along, is how to act when you have an acknowledged deficit of hard evidence. The business world is not that different - many of my customers are riding their hobby horses based largely on gut-feel and collecting facts to feed their opinion, which is why some investors pay me to do a sanity check.

When I reflect on this transportation debate, which has been occupying the academic community for almost 100 years, I am amazed that the role of glaciation has not been absorbed into basic thinking. It seems by far the most likely on the basis of "rational plausibility" and we should be directing investment this way rather than trying to figure how many ropes are needed to pull x tons so many kilometers. Actually, I think we should just accept glaciation as a basic theory and move on to the really interesting stuff like the purpose of Avebury/Stonehenge/etc.

BRIAN JOHN said...

Thanks Chris --
interesting thoughts. I suppose this sort of debate takes place in all disciplines -- and especially at the interfaces between two disciplines. The RSC discussion is probably typical -- on whose territory does the discussion belong? I think it's my territory, because it's obvious to me that the large recumbent stones are erratics -- but archaeologists think it's their territory because the stones have been built into man-made monuments. So I assume that my opinions should be accorded more respect, and the archaeologists probably think I should accord them more respect!

One thing that has happened -- and I have commented on this before in the blog -- is that geologists and geomorphologists have not been aggressive enough in arguing the case for their own disciplines. So archaeology has made all the running, with the help of the media and the research councils, so that a scenario has developed in which earth scientists are pulled in simply "in the service of archaeology". So the archaeologists control the agenda and control the means of publication.

It's a very sad thing, for example, that the recent Ixer/Bevins paper on Rhosyfelin was published in an archaeology journal rather than a geological journal. I would really like to see a proper geological debate about their findings, but we probably won't get it, unless they present their results to one or another of the geological conferences.

So Earth Scientists of the world, unite! Show the world that geology, glaciology and geomorphology are mature and serious sciences which should be given due respect!

Geo Cur said...

Chris , glaciation ,the use of erratics in monuments has long been accepted in archaeology .I can’t think of any archaeologist who does not accept it .
I don’t know to what extent the human transport of small- large stones over short - long distances in areas where glaciation could not be an explanation is accepted in the earth sciences but it certainly is in most other disciplines .
In the case of Stonehenge there is the possibility that both may be involved in the explanation .

Geo Cur said...

Brain ,on the Chris Clark Britice map , do those large white areas away from the green arrows e.g. one point NJ 81770 37811 , indicate that that there is no erratic path in that area ?

BRIAN JOHN said...

Since the whole area was covered by moving ice, erratics could have been moved anywhere on the mapped area. Chris and his fellow workers have simply picked out those erratics that have been easiest to provenance. Note that the trails were not necessarily directly from source to arrow head -- as the key indicated, the routes taken by erratics might have been zig-zag routes, and might have been over several glaciations.

chris johnson said...

Hi Geo,
I am reassured by your confidence that all archaeologists know about glaciation and erratics.

Perhaps I am overly influenced by just having finished Oliver's book "A history of Ancient Britain", published in 2011, which was "dependent upon the efforts of a whole range of thoughtful and painstaking professionals". On page 119 we get to Stonehenge, "we know for certain that the first stone circle at Stonehenge was built of Presceli bluestones - more than 200 tons of the stuff hacked out of the welsh hills and transported 150 miles" Further down, "around 3000 BC the Herculean effort was made to bring in the Bluestones .. from Preseli". Not a word about a glacial contribution, even as a vague possibility.

Oliver is a trained archaelogist, I am led to believe, and quite an influential chap these days.

BRIAN JOHN said...

Poor Neil -- he obviously doesn't have a clue what it means to be a thoughtful and painstaking professional. He is a media man, after all, and in the media you NEVER want the truth to get in the way of a good story.

Geo Cur said...

Chris , whilst not supporting Neil Oliver , I'm sure he is perfecly aware of the probable use of erratics in monuments which is actually what I mentioned, the same would apply to any of the other stonehenge strong human transport idea . If you are looking for lazy writing I'm sure there is a lot more to be found in his book , if his tv stuff is anything to go by .

Geo Cur said...

Here's an example of a marked erratic very like a recumbent which I discovered a few years ago .You have to scroll to find pics of the main rock in it's setting .
Never any suggestion this was other than natural ,apart from the markings .

chris johnson said...

Brian, returning to the theme and your last post to me in this thread, I recognize what I call "the silo effect". We live in an increasingly specialized society and given recent changes in the education system it can only get worse.

What is needed to resolve this debate is a meeting of minds from several disciplines - what we in the business world would call an "across-function off-site" with plenty of blank flip chart paper and marker pens.

Perhaps something "Stonehenge Thoughts" could put together? Prejudice to be left outside the room and data points please. Who knows, edited highlights might even be televised!

Anonymous said...


I second that suggestion! I think Brian's blog can be that place!

On the topic of 'evidence'. Though it's hard to disagree with anything Brian says, I agree with you that too much reliance on 'expert evidence' is no sure way of arriving at the truth. Experts also told us Saddam had WMDs. Or in earlier times the Earth was the center of the Universe.

I have often stressed in previous comments 'raw evidence' vs. 'interpretations' based on certain accepted theories. In the case of Stonehenge, 'raw evidence' would be such things as the concentric design, the 'empty quarter', the Avenue stripes, the 'foliated rhyolite fragments', the alignment of the Avenue, the outer circular ditch dug up in segments, the empty pits and so many other indisputable 'facts on the ground'.

On the other hand, I don't place too much reliance on carbon dating of different Stonehenge 'stages' since these depend on such things as 'deer antlers' which could have been brought to Stonehenge by natural processes. Nor do I take as evidence the use of deer antlers as the tools used to dig the ditch. These at best are 'interpretations' based on the 'human agency' hypothesis.

We should start afresh and ask 'what working hypothesis best fits the raw evidence'? What I have argued in the past is a 'local ice cover' of Salisbury Plain fits the raw evidence and can provide simple, sensible and consistent explanations for these. Of course, we have no 'direct evidence' for this hypothesis, nor any other hypothesis. Such is the nature of hypothesis. We can never prove a hypothesis, but only disprove it. The reason why any working hypothesis must be falsifiable to be science. This hypothesis is falsifiable.


chris johnson said...

On the contrary. The best way to establish rational plausibily is to talk with experts. In the case of WMD it was not the experts that got it wrong, and for early astronomy people did the best they could in their context. I am afraid you start from a false premise.

BRIAN JOHN said...

Quite right, Chris. The experts (including poor David Kelly -- God rest his soul) got it right -- and it was those devious gits like Blair and Campbell who decided to twist the evidence in their possession for their own political ends. There's a lesson in all of that.....

Anonymous said...


I have no trouble talking to experts or anyone else for that matter. I exclude no one from any honest and sincere conversation searching for truth. I think you may have misread my comments.

Some truths may lie 'outside the box' of accepted theories. Certainly we can never know that a priori! For this reason we are best guided by the indisputable 'raw facts' rather than 'interpretations' based on established theory.

Above all, we must keep an open mind! Often, 'experts' forget that!


chris johnson said...

I think we talk about "process" in this thread, and then I would take issue with the approach you are suggesting. We are better to rely on experts with many years experience to interpret raw facts than try and do it ourselves. When experts are unsure or unconvincing we can look for a second opinion, or identify the missing piece we need to find. When experts need to learn from other experts - i.e. archeologists and geomorphologists then we move quicker via debate than by challenging the others raw data.

Your antler example is a case in point. There is such a volume of circumstantial evidence that has been looked at by so many expert eyes that I see no value for another discipline to challenge the theory that antlers were used as construction tools.

I fully agree that we always need to keep an open mind but not to the extent of becoming vacuous.

BRIAN JOHN said...

...and most of the "expert" opinions are based on common sense. For example, if a scatter of charcoal is found in the bottom of an Aubrey Hole, that means it got there after the hole was dug and before the hole was filled in. Then there's my example of the flattened Coca cola can underneath a large recumbent stone. Normal stratigraphic principles apply. I'm prepared to accept that for most of the time, experts get it right -- and the evidence that antlers were used as picks seems to me to be incontrovertible.

Anonymous said...


The question is not whether the pine charcoal got to the pit before the pit. Rather, what is the charcoal found in the pit doing in the pit!

Experts tell us these two pieces of pine charcoal are the remains of human cremation. Since we have no 'direct evidence' (historical records and the like) to give us the answer, we only have 'interpretations of the evidence' based on hypotheses (beliefs) assumed to be true. And if these beliefs are held by 'experts', acting as 'high priests' of the current thinking, Chris would have us bow down in reverence to their Certificates of Higher Thinking.

Sorry! I come from a long tradition of bowing down to no one but Reason.

Chris: Is thinking for ourselves the 'process' you object? Are you suggesting 'mindless control' by letting others do our thinking?


BRIAN JOHN said...

Kostas -- bits of charcoal are not evidence of human cremations. Burnt or charred bits and pieces of human bone or teeth are evidence of human cremation (or cannibalism, if you want to be really imaginative...). I dare say that the archaeologists are sensible enough to know the difference between the one and the other.

Anonymous said...


The bit about pieces of charcoal as evidence for human cremation goes back to some intense discussions I had with Geo Cur in your blog several months ago.

But be that as it may. Why should “Burnt or charred bits and pieces of human bone or teeth are evidence of human cremation”? As you already admitted, there is room here for other 'interpretations of the raw evidence'. I can think of even other scenarios.

Most telling of all, since when do you think “archaeologists are sensible enough to know the difference”? And what if their thinking is skewed to a prejudiced conclusion knowingly or unknowingly? Should we always obediently accept their pronouncements as 'experts'? And what is so wrong about challenging anybody's reasoning and belief system? Like we often do in your blog? Are 'experts' the intellectual 'holly cows' not to be touched or questioned? I find that particularly objectionable! Chris I am sure thinks I am wrong!


BRIAN JOHN said...

It makes me feel slightly uncomfortable, defending archaeologists, but I do at least give them credit for being intelligent human beings who try to examine the totality of evidence at a site before stating that they are dealing with cremated remains -- or whatever. Your type of blanket cynicism is counter-productive, as I have said many times before, especially when you have patently not examined the literature properly.

Anonymous said...


Don't get me wrong. I do admire and respect all human achievements. Including those by 'specialists'. And I wont question their technical knowledge. Like I wont question my car mechanic fixing my car (though in all honesty, sometimes I think I should!)

But even specialists are people too! And like the rest of us they are 'under the influence' of their theories. There is nothing 'real' about any theory! These are human creations. They represent a view. They can and should be challenged! Prehistory theories especially. With no historical records and lots of made up stories.

Does the archeological discovery of the tomb of the architect of Stonehenge make sense to you Brian? We all looked at the 'raw evidence'. Anything there to convince you the excavation site is of an architect? Should we acquiesce and admire the emperor's new clothes?

Truth has nothing to fear but fear itself! We must be courageous in spite of the pressure!


Jon Morris said...

Interesting thread.

"So the archaeologists control the agenda and control the means of publication."

But this subject is seen to be their general field rather than other specialists? I see where you're coming from, but archaeologists are specifically employed to determine the nature of the past whereas other specialists rarely are.

So shouldn't they be in the position of being referred to for the task that they are specifically employed to do?

The question of who carries the weight usually goes with who carries the can if things go wrong. Not sure if that applies to archaeologists.

Overloaded with work! makes a nice change.