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

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

“Science is an ongoing race between our inventing ways to fool ourselves and our inventing ways to avoid being fooled.”- Saul Perlmutter, Astrophysicist and Nobel Laureate.

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 an observation or an idea can be true, but there are an infinite number of ways in which it can be false, including the multiple ways that neither you, nor anyone else, has yet thought of.

“The unknown is the dark matter of all things, the greater part of the universe.” Geoffrey Weiss.  Post in, June 2021

I digress here to the Law, or more specifically, Criminal Jurisprudence. This subject might seem a long way from that of geological mapping, but it provides a good way of illustrating the difference between fact and evidence, truth and opinion.  Lawyers prosecuting or defending a person accused of crime get equal time to present evidence – which is often conflicting – to an experienced judge or a randomly-selected, 12-person Jury. It is then the job of the Judge or the Jury, having heard all the evidence and the arguments, 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, time-consuming and expensive process – the best system that centuries of jurisprudence has yet devised – they often get it wrong. Juries (and Judges) are human beings, not always rational, subject to error, misunderstanding, emotion, group think, societal prejudice, fashionable opinion, deference to authority and uncritical acceptance of expert opinion.

The current proliferation of  “fact” checkers on electronic media assume the role of guardians of fact and custodians of truth with apparently little apparent awareness of their own potential biases. But I will leave that subject for another blog post, which you can read here.

At least the Lawyers have a definition, albeit limited and subjective, for what they mean by “fact” and “truth”.  Many 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 bio statistician Sir Ronald Fisher gave a (sort of) definition of scientific fact in 1926, when he wrote (in 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 result is 0.05 or less (or 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 and thus “a scientific fact”.  If p=0.05 is considered significant, what then of p=0.06?  If this number is also significant, what of 0.07? And so on. What is the logic of imposing any arbitrary cut-off in a continuum of potential results? This is not science, but simply a way of putting an illusion of quantitative rigor onto woolly qualitative results.

Despite Fisher’s eminence and authority, I doubt many scientists today would consider statistical significance, however narrowly defined, as defining scientific fact. In spite of this, researchers in soft sciences like psychology, social science, political science or economics, or even in fields of genuine hard 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 (and the results which fail to make the cut left languishing in a drawer).

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 randomly loaded with live bullets and the remainder with blanks, would you spin the barrel, put the muzzle in your mouth and then 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 after a long diversion 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, from Relativity to Rastafarianism, 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 scientific endeavor 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 that happens to take place in, and defines, what we call east.  But the illusion was good enough to fool the best brains of humankind for millennia. And the earth is not round – it’s not even spherical: this is a convenient simplification, but a simplification good enough for everyday discourse (the earth is, of course, a slightly lumpen and asymmetric oblate spheroid). 

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