Fact, Truth, and the Scientific Method

Is there such a thing as a geological fact map? Can we justify the widely used term ground truth to describe such a map, or indeed any direct geological field observation? This is not just a question of semantics. Surface indications of ore are usually subtle, and your predecessor’s claim that their observations represent “fact”, let alone the “truth”, should never be taken at face value. Yet these descriptors are very commonly used by economic geologists. The purpose of this essay is to persuade you that we should abandon these terms.

A map is a two-dimensional virtual reality representation of a portion of the earth’s surface. A geological map is an artifact constructed according to the theories of geology and the purpose of its maker in putting it together (i.e. his or her biases). It presents a selection of field observations and is useful to the extent that it is a graphic which aids the prediction of things which cannot be observed. There are different kinds of geological map. With large‑scale maps (i.e. detailed maps of small areas, generally 1:500 to 1:2500 scale), the geologist  aims to visit and outline every significant rock outcrop in the area of the map. These are often called “fact” maps or even “ground truth” maps acquired through a process of (ouch) “ground truthing”.   But geologists, indeed all scientists, should scrupulously avoid the words “fact” and “truth”.  A much better descriptor for such maps is “observational” or simply “outcrop”. In a small‑scale map (which covers a larger area: but the terms small-scale and large-scale are relative), visiting every outcrop would be impossible. Generally, only a selection of available outcrop is examined in the field and interpolations made between the observation points. Such interpolations may be by simple projection of data or by making use of features seen in remote sensed images of the area, such as satellite imagery, air photographs, aeromagnetic maps and so on. Small‑scale maps thus generally have a much larger interpretation element than large‑scale maps, but no geological map, at whatever scale, is ever free from interpretation, or from the biases of the observer.

Outcrop geology map

A portion of a large scale (original at 1:2000) outcrop geology map, called by some a “fact” map. The author was an economic geologist: his biases and purpose in making the map are obvious. Another geologist, with different biases, would have made a very different map. Click for larger, sharper image.

“Fact”, and the related but more portentous idea of “truth”, are abstract ideal concepts. They are loaded words that are too often used as a means of asserting authority and preempting debate. When you say, “this is a fact” you are saying, in effect, “you may not dispute this”. When you say, “this is the truth”, the unstated implication is that those who disagree with you are deniers, heretics or contrarians. Recall, from your own experience, how often in debate these phrases are used to introduce a controversial statement that the speaker knows you might well not accept and wants to ring-fence in advance against your anticipated skepticism. Phrases such as “in fact…” or “the truth is..” are standard figures of speech that we all use in conversation as a means of emphasizing the strength of our belief. You are entitled to respond: “that’s not a fact, it’s just your opinion” – or – “where’s your evidence?”  But quoting “fact” and “truth” are always to weaponize these words in pursuit of an agenda (e.g. to persuade, to win an argument, to convince a doubter). Evidence for this abounds from all fields of communication: the words “fact” and “truth” are stock phrases used in advertisements to convince you to buy a product; they populate the language of journalists and of politicians[1] trying to convince their readers or influence their electorate.

At the most fundamental level, the ideas of objective fact and truth are ideal philosophical concepts that we can only seek to achieve. Claims of absolute fact and enduring truth belong to the realms of faith and belief[2]. The Scientific Method is not based on faith or belief but on evidence. At any rate, that is the ideal, and is the process which underpins the authority of science to speak on the natural world. Evidence (and its digital version, data) is not the same as fact, though the two ideas are often conflated. “Alternative evidence” is the proper subject of much scientific discourse: “alternative fact” is an oxymoron[3]. There is only ever one way that something can be true, but there are an infinite number of ways in which it can be false, including multiple ways that neither you, nor anyone else, has thought of.

I digress here to two subjects that might seem a long way from geological mapping, but both provide a good way of illustrating the difference between fact and evidence, truth and opinion.

The first subject concerns “fact’ checking. The current proliferation of “fact” checkers on Social Media platforms, web sites such as politifact.com and factcheck.org, or on “our” ABC, assume a god-like knowledge and ex-cathedra authority that never acknowledges, or is apparently even aware of, their own potential biases.  Google, Facebook, the ABC, the Royal Melbourne Institute of Technology, The Conversation along with many other media organisations worldwide, are members of the International Fact Checking Network. IFCN is a division of a small South Florida Journalism school called the Poynter Institute. As well as the IFCN, the Poynton Institute also operates the politifact.com and mediawise.com web sites. These “fact” checkers mainly concern themselves with politics but also pronounce on hotly-debated areas of science and technology such as climate change, energy policy and (unsurprisingly, given the current crisis), epidemiology.

truth o meter

The Truth-O-Meter: a graphic used by the Poynter Institute to illustrate their opinion.

Who are these self appointed Custodians of Truth?  Perhaps a panel of retired Judges experienced in impartial judgement and the sifting of conflicting evidence? Perhaps a range of scientists with appropriate knowledge of a subject and a lifetime of applying the Scientific Method? Perhaps a broad spectrum of randomly-selected citizens impaneled to select between competing claims on the basis of life experience and common sense?  Perhaps a military style adversarial blue team v red team approach? No, none of the above, but “journalists and media experts”. And not just any journalists out there in the real world filing copy for a living, but salaried academic journalists in media schools. Can we expect objectivity from this source? Not according to Emeritus Professor Ted Glasser, current Head of the Department of Communications, Stanford University and for nineteen years head of their School of Journalism. In a recent interview with The Stanford Daily, Glasser is quoted : ” reporters must embrace the role of social activists and it is hard to do that under the constraints of objectivity”.  If this is what is taught at Stanford, then, at the very least, one would have to be cautious of any “fact” check carried out by one of their graduates.

Guardians of Truth (cropped)




Wannabe Guardians of Fact and Custodians of Truth: participants at the International Fact Checking Network Summit, Cape Town 2019. Quis custodiet ipsos custodes? 

My objections the groups operating under the umbrella of the IFCN is not with their stated aims (which are noble) or their conclusions (which I might well agree with) but in their use  of the words “fact” and “truth” in order to award themselves the mantle of authority and infallibility.  The use of these words implies a value judgement and indicates that their primary aim is to persuade, rather than merely inform. If the groups were called, and operated, as “evidence checkers” they arguably would have a useful role to play, provided they presented all the evidence, in a fair and balanced manner, with acknowledgement of area of uncertainty. The aim of an evidence checker should be to present information for readers to form their own judgement. This is not easy with the soi-disant fact checkers where some of the information presented comes pre-labelled  as “fact” and “truth”, and some as “false”, or even “pants on fire” (American rhyming slang: meaning “liar”).

These ideals for communicating evidence are set out in a timely November 2020 article in Nature, entitled: Five rules for presentation of evidence. (Michael Blastland & co-authors, Nature 587, 362-364 https://doi.org/10.1038/d41586-020-03189-1). The article is aimed at scientists but should be essential reading for every self-appointed “fact” checker.

My second example of the distinction between evidence and fact comes from the field of criminal prosecution. Lawyers prosecuting or defending a person accused of crime present evidence – often conflicting – to an experienced judge or a randomly-selected, 12-person Jury. It is the job of the Jury to determine “fact” by giving a guilty-not guilty verdict. But the legal definition of fact to which they must adhere is limited and qualified. It is an opinion to which all 12 Jurors must agree and which they consider to be “beyond all reasonable doubt”. And in spite of this laborious and time-consuming process, fine-tuned over centuries of jurisprudence, they often get it wrong.

At least the Lawyers have a definition, albeit subjective, for what they mean by “fact” and “truth” (beyond all reasonable doubt). Scientists, on the other hand, tend to use these words to mean, like Humpty Dumpty in Alice in Wonderland, whatever they want them to mean. The famous statistician Sir Ronald Fisher gave a definition of scientific fact in 1926 (Journal of the Ministry of Agriculture of Great Britain, 33, p 504):

a scientific fact should be regarded as experimentally established only if a properly designed experiment rarely fails to give this level of significance.

By this level of significance, Fisher  meant that the probability (known as p) that pure random noise in the data would yield your results is 0.05 or less (p ≤ 0.05 : e.g. five or less chances in a hundred). If such a number can be calculated then, according to Fisher, a p≤0.05  enables you to call your result “statistically significant”.  Despite Fisher’s eminence and authority, I doubt many scientists today would consider a statistical significance as defining scientific fact. However, researchers in pseudo sciences like psychology, social science, political science or economics, or even in fields of genuine science such as medical research, have to make sure they meet Fisher’s arbitrary  “wee pee” criterion if they want their work to be published.  A geologist would doubtless consider a 95% or better chance that he or she is on right track to be the basis for a pretty good working hypothesis, but they would hardly bet their lives on it.

Thought experiment: if you had a (hypothetical) revolver with 100 chambers, five of which were loaded with bullets, would you spin the barrel,  put the muzzle to your head and pull the trigger in order to explore the “true” meaning of statistical significance?

None of the above is to dispute that an observation (evidence) can be so well established by universal experience that for all practical or everyday purposes can be called a ‘fact” that few rational people would dispute without being dismissed as a boring pedant or a nut case (maybe you already fit me with one of these hats?). That the sun rises in the east or that the earth is round are all, by this definition, statements of fact[4]. But, to return to the main subject of this essay, when a geologist produces a large-scale outcrop map and calls it “fact” or “ground truth” I do not think we have to accept that his or her lines on a piece of paper can be described with the same level of certainty.

Sun rises in the east

The sun rises in the east. Fact…or an optical illusion?

You may think on reading the above paragraphs that I have strayed into the area of post-modern philosophy called Relativism. Relativism denies that there is any objective truth out there: all systems of knowledge and ideas are social constructs and all such constructs, from Dark Matter to the Dreamtime, have equal validity. That is neither my opinion nor the point I wish to make. My point is this: in their professional writings Scientists should avoid using the words “fact” and “truth” and accept that all their observations and theories are subject to scrutiny, qualification, and skepticism.

In the real as opposed to the theoretical world, truth, like beauty, is in the eye of the beholder. One observer’s “ground truth” could be another’s irrelevant noise.

The purpose of science is to seek truth, not proclaim it.

(This post is a greatly expanded and rewritten update of a previous post first published in 2015, entitled: “Is there such a thing as a geological fact map?)


[1] For maximum impact, Al Gore’s 2006 disaster movie was titled “An Inconvenient Truth”. As an ex-politician he knew the technique. A technique good enough to win him a joint share of the 2007 Nobel Peace Prize.

[2] The legendary editor of the Manchester Guardian, C P Scott, acknowledged this in 1921 with his famous quote: “comment is free, but facts are sacred”. A noble sentiment, but how could he, or the generations of journalists who followed,  be sure they always know the difference?

 [3] When Donald Trump’s campaign manager Kellyann Conway used the phrase “alternative fact” in a 2017 interview she was widely ridiculed. “Alternative facts are not facts” spluttered her interviewer “They’re falsehoods”. And he was right.

 [4] The sun does not “rise” – this is an optical illusion, but an illusion good enough to fool the best brains of humankind for millennia. And the earth is not round – not even spherical:- this is a convenient simplification, but a simplification good enough for everyday discourse. The earth is, of course, a slightly lumpen oblate spheroid. 

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