Antivaccine nonsense Evolution Holocaust Holocaust denial Skepticism/critical thinking

Falsus in uno, falsus in omnibus: A legal, not scientific, principle and example of dichotomous thinking

Falsus in uno, falsus in omnibus (false in one thing, false in all things) is a legal principle. That doesn’t stop cranks from misusing it to cast doubt on science that they don’t like. Overall, it’s just another form of black/white dichotomous thinking.

After my post on Monday about how one major flaw in thinking that contributes to science denial is dichotomous thinking, or casting an issue for which evidence exists on a continuum as black and white, yes or no, 100% effective and safe versus useless and dangerous, I was thinking about other errors in reasoning favored by science deniers. Then—lo and behold!—the other day I came across just such an example. Even better, it’s an example of a flaw in reasoning that I haven’t discussed in several years, which means that, even though I have discussed it once before, it’s worth discussing again now. I’m referring to the misuse of legal principles to argue science, in particular the idea of falsus in uno, falsus in omnibus. I was “inspired” (if you can call it that) by this:

Mr. Schlichter is a columnist at and, apparently a lawyer. He’s also clueless about science. In any event, my first reaction this was to point out that this wasn’t a courtroom; science is not decided by legalistic arguments; and that’s not how things work in science. It also reminded me of how science deniers misapply legalistic thinking to science in a way that is very much of a piece with the dichotomous thinking that I described on Monday. I’m referring to the legal principle of falsus in uno, falsus in omnibus.

Falsus in uno, falsus in omnibus is a legal principle, not a scientific principle.

Falsus in uno, falsus in omnibus, put quite simply, means false in one thing, false in all things. It’s a legal principle that dates back to ancient Rome that indicates that a witness who is false about one matter can be considered to be not credible in all matters. This principle is why lawyers are often so aggressive at trying to impeach the credibility of a witness and lawyers on the other side labor so hard to prevent that from happening. If a witness can be shown to have been badly mistaken or to have lied about one thing, then by the principle of falsus in uno, falsus in omnibus, it is reasonable to question everything else in that witness’ testimony. In a criminal case such questions could easily be enough to cast “reasonable doubt” on the testimony. Now, there are two things to remember about this principle. It generally applies only to the evaluation of the testimony of one witness, not to the entire case. Second, it’s a legal principle, not a scientific principle. Science doesn’t work that way, as I’ll elaborate on in a moment. Of course, falsus in uno, falsus in omnibus is, at its core, dichotomous thinking. Either every part of an argument is 100% true and correct, or it’s false. Either all evidence supports a conclusion, or the conclusion is false, and if anyone ever in history involved in supporting an argument has ever lied about anything or been very much mistaken, then the whole body of evidence is invalidated.

My favorite example comes, oddly enough, not from science but from history. Specifically, it’s an argument that I’ve seen Holocaust deniers use on numerous occasions. I’ll just give you one example. One claim regarding the Holocaust is that Nazis manufactured soap out of the fat from their victims. It turns out that, although there is evidence that the Nazis did make attempts to make soap out of their victims, the overwhelming majority of Holocaust historians have never believed that the Nazis mass produced human soap. None of that stopped Holocaust denier Mark Weber from writing this as an introduction to an article discussing the limited evidence for the manufacture of soap from the victims of the Holocaust:

For half a century now historians have told us that during World War II the Nazis had a policy to exterminate the Jews of Europe, along with homosexuals and Gypsies. We are told that millions were “gassed” at German camps such as Auschwitz and Treblinka.

We have been told that the ghastly process of mass murder was also carried out in Belzec, Buchenwald and Sobibor. And aren’t there thousands of survivors who “escaped the gas ovens” and swear that all this is true?

And didn’t the Nazis make lamp shades from human skin, and manufacture soap from the fat of exterminated Jews? Of course, you may answer, everyone knows it. After all, aren’t such bars of “Jewish soap” on display in museums in Israel and other countries? How can there be any doubt?

“Falsus in uno, falsus in omnibus,” or “false in one thing, false in everything,” was a Roman legal principle. If a witness may not be believed in one thing, he should not be believed in anything. This principle is as valid today as it was two thousand years ago.

Of course, whether or not the Nazis ever did manufacture soap out of the remains of their victims has no bearing whatsoever on the historicity of the Holocaust and historical fact that the Nazis instituted a program of mass murder on an incredible scale to exterminate European Jewry that very nearly succeeded. That the myth of “millions of Jews being turned into soap” became so commonplace and pervasive outside of historical circles is similarly irrelevant to the historicity of the Holocaust. It does, however, provide Holocaust deniers an excuse to trot out falsus in uno, falsus in omnibus, even though whether or not the Nazis ever actually manufactured soap from their victims has no impact on the overwhelming masses of evidence that lead to the inescapable conclusion that that Nazis murdered roughly 6 million Jews.

Holocaust deniers use the principle indiscriminately and incorrectly, too. For example, they love to zero in on eyewitness accounts of death camp experiences or of Nazi atrocities that don’t quite add up and point to them as though a handful of inconsistent or false stories about the Holocaust invalidate all the other evidence supporting the historicity of the Holocaust. Alternatively, they love to harp on the discovery of a false “Holocaust survivor,” as if finding out that someone lied about having survived a massacre or being in a camp during the Holocaust somehow invalidates the historicity of the Holocaust.

Or, as Gord McFee once put it:

Since, as this list shows, the amount of empirical evidence for the Holocaust is so overwhelming, the “revisionists” must throw in another dismissal trick. This has been called the “falsus in uno, falsus in omnibus” condition (one thing mistaken equals all things mistaken). It means, for example, that if any single piece of survivor evidence can be shown to be wrong, all survivor evidence is wrong and is to be dismissed. If any Nazi official lied about an aspect of the Holocaust (on-topic or not), all Nazi officials lied, and anything Nazis said after the war is dismissed. If any Nazi can be shown to have been tortured or mistreated, they all were and anything they said is invalid.

Obviously, it’s not just Holocaust deniers. it’s antivaxers too. Let me make it clear that I am not saying that antivaxers are Holocaust deniers or antisemites (which all Holocaust deniers are), although I’m sure there will be antivaxers out there who try to dishonestly misrepresent what I’m saying that way. True, I have encountered bigoted antivaxers, but what I’m talking about here is a fallacy in reasoning shared by all science (and history) deniers.

An example of this misuse of this legal principle comes from Mayer Eisenstein, the Chicago doctor who claimed that he doesn’t vaccinate and that he’d never seen a case of autism in his large practice in this 2012 Autism One quackfest presentation:

20th Century medicine has been shown to be false in many of its assumptions and it has held physicians with non-interventionist philosophies to a higher standard than interventionist physicians. The unscientific thinking of “I think therefore I believe” has replaced scientific evidence based decision making. How can we have trust in a medical system which has been shown to be untrue in some of its practice? The answer is with great scepticism. Let us pray that scientific reason will prevail and the motto for the 21st

Here’s another example from Trung Ngyuen that uses some rather strained prose:

The legal maxim, falsus in uno, falsus in omnibus , might with propriety be applied to those who deceive patrons and falsify records to save a medical dogma from deserved reproach.

The author of the foregoing quotation is probably no more blameworthy than many others who are active and unscrupulous promoters of the Jennerian theories, but we submit that this quotation may be a fair expose of the ethics of that class of medical practitioners who “desire to preserve vaccination from reproach.” That they have deliberately falsified the records is well known, but their motive for so doing may not be as thoroughly understood by the public as it should be.

“Jennerian theories”? That’s a dead giveaway that Ngyuen is an antivaxer.

A “classic” of the antivaccine genre of misusing falsus in uno, falsus in omnibus comes from Paul King, the Science Advisor and Secretary of the Coalition for Mercury-Free Drugs (CoMeD), who presented a statement to the World Health Organization’s Strategic Advisory Group of Experts on Immunization (SAGE) meeting in Geneva in April 2012. It consists of a lot of fallacious arguments claiming that the mercury-containing preservative thimerosal that used to be in many childhood vaccines until 2002 causes mercury. In it, King uses some rather old and bogus arguments favored by antivaxers similar to these about a single paper that failed to find a correlation between exposure to thimerosal-containing vaccines and autism risk, concluding:

Given the preceding realities, it seems clear that the WHO has two (2) paths that it can take from this day forward.

Either the WHO can “suddenly” see the light and support the “immediate” banning of the use of Thimerosal and any other mercury compound in the manufacture of any vaccine or other drug product, or the WHO can continue to be a part of the “lie” that Thimerosal is “safe” and risk having the countries of the world discover the “lie” and not only stop the use of Thimerosal but also stop the use of any vaccine – on the basis that, if the WHO/CDC/vaccine makers/public health officials are “lying” about the harm from Thimerosal in vaccines, then they are probably “lying” about the safety of all vaccines – falsus in uno, falsus in omnibus – indicating that any person who willfully falsifies one matter is not credible on any matter.

This commenter does not know the choice the WHO will make but he does understand what the logical outcomes of either choice will probably be.

Thus, the WHO needs to choose its path; but, it should choose carefully since the “lie” that was hidden has been revealed and the truth about this “lie” is spreading rapidly across the world!

Remember, this was about just one major study from Denmark in the early 2000s. Even if every single critique of the study made by King were absolutely valid (and they’re not), it would just be one study from one country’s health authorities. There are many other studies that fail to find a link between thimerosal-containing vaccines and autism. Removing this one study from the scientific literature would not change the scientific consensus that mercury in vaccines is not a cause of or predisposing factor for autism.

Another example of this phenomenon is the antivaccine obsession with an investigator named Poul Thorsen, who was involved with the same study. Without going into too much detail, Thorsen was accused of misuse of grant funds and absconding with $2 million. As I noted at the time, though, far from being a leading figure in the two Danish studies that failed to find a link between vaccines and autism, Thorsen was in the middle of the list of authors, neither first nor last, the two most important positions, denoting the one who did the most work and wrote the paper and the senior investigator, respectively. Also, to reiterate, even if the Danish studies removed from the scientific literature as untrustworthy due to fraud, that would still not invalidate the scientific consensus that thimerosal in vaccines do not cause autism.

In fact, we see the very same misuse of this principle in alternative medicine circles as well, where it takes an even broader, more insidious form. (Truth be told, antivaxers are partial to this form too at times.) That form is to argue that because conventional medicine has been wrong before about the cause of a disease, we should not trust the present consensus about the cause and treatment of the disease and then to argue by implication that their quackery works. (Conveniently, they forget that, even if they’re correct about science being wrong, that does not absolve them of the obligation to show that their therapy works.) A particular favorite example of this ploy is to point out how medicine was wrong about the cause of duodenal ulcers, having previously thought them due to diet or other predilections until it was shown over the last 30 years or so that most cases of such ulcers are caused by a bacterium, H. pylori. Never mind that it was science, not alternative medicine, that figured out its own error and that treatments used for duodenal ulcers before the discovery of H. pylori were in fact fairly effective. They were just significantly less effective than the treatments we have today and all too often requiring surgery.

Let’s get back to the core issue. Falsus in uno, falsus in omnibus is a legal principle, not a scientific or investigative principle (or a principle in history investigation). It makes sense in the courtroom when assessing the credibility of a single witness. If that witness lied about one thing, then of course you’re going to question everything else that witness testified to. The problem is, this principle doesn’t work in science. Why? The scientific literature is littered with papers whose results were later shown to be either incorrect, mostly incorrect, or only partially correct. In the vast majority of cases, being incorrect about one conclusion doesn’t mean the scientists were lying, and when assessing the conclusions of science (or, for that matter, history) with respect to a given question it is the totality of the evidence that must be weighed.

Moreover, it is not valid to treat all of science as a single source. Science is not a single witness that can be interrogated. Well-accepted scientific theories (like evolution, for example) are supported by many interweaving lines of evidence from many different sources and disciplines. Certainly, you can impeach one minor source or piece of data, but that will not invalidate the rest of the supporting data undergirding, for example, the theory of evolution. Yes, one must concede that there can potentially be some pieces of data that, if ever found, would cast serious doubt on the theory of evolution. That is, however, never the sort of data that creationists present. The same is true of the pieces of data “casting doubt” upon the Holocaust trumpeted by Holocaust deniers and of pieces of data trumpted by alternative medicine mavens casting doubt on the efficacy of conventional medicine.

Finally, when scientists find inconsistencies in the data supporting a hypothesis or theory, they do not reject the entire theory out of hand in this manner, as cranks do. Rather, they use anomalous observations or experimental results as a springboard on which to improve our understanding of a phenomenon. They see if the existing theory can be modified to account for the anomalous observations. They make hypotheses about potential explanations of the anomalous observations and then test them experimentally. They seek to determine whether a new theory with better predictive power and utility than the old can be developed, either by modifying the old or by building a new theory, that takes account for the new observations and makes more accurate predictions. Of course, this particular “science was wrong before” fallacy depends on the mistaken belief that there is absolute truth in science, when in fact all scientific knowledge is provisional and vulnerable to be proven incorrect by future experiments or evidence. That self-correcting mechanism of science is not a weakness at all, but rather sciences’ greatest strength, in which present concepts and theories are constantly subjected to testing and attempts to falsify them. Those hypotheses that can stand up to such attempts become accepted as closer to the “truth” than previous understandings (and may even reach the level of being called a theory), and, with each successive iteration, scientific understanding eliminates error and comes closer to the way things “really are.”

To bring it on home, I’ll paraphrase something sometimes said about the way cranks use evidence and science. In brief, cranks use falsus in uno, falsus in omnibus the same way a drunk uses a streetlight, not for illumination but for support. They creates the sort of false dichotomy that I wrote about yesterday: Either everything is true, everything is correct, or nothing is true or correct. A single minor inconsistency, a single case of scientific (or financial) fraud, a single instance where a study was found to be incorrect and reversed can be reason enough for cranks to make sweeping claims about how the “edifice” of the science or history they hate is “crumbling” (and therefore their views could well be correct). When will they learn that science is not the law and that scientific questions are not answered using the same methods as legal questions? My guess is that they probably never will.

And don’t get me started on the concept of “reasonable doubt.”

By Orac

Orac is the nom de blog of a humble surgeon/scientist who has an ego just big enough to delude himself that someone, somewhere might actually give a rodent's posterior about his copious verbal meanderings, but just barely small enough to admit to himself that few probably will. That surgeon is otherwise known as David Gorski.

That this particular surgeon has chosen his nom de blog based on a rather cranky and arrogant computer shaped like a clear box of blinking lights that he originally encountered when he became a fan of a 35 year old British SF television show whose special effects were renowned for their BBC/Doctor Who-style low budget look, but whose stories nonetheless resulted in some of the best, most innovative science fiction ever televised, should tell you nearly all that you need to know about Orac. (That, and the length of the preceding sentence.)

DISCLAIMER:: The various written meanderings here are the opinions of Orac and Orac alone, written on his own time. They should never be construed as representing the opinions of any other person or entity, especially Orac's cancer center, department of surgery, medical school, or university. Also note that Orac is nonpartisan; he is more than willing to criticize the statements of anyone, regardless of of political leanings, if that anyone advocates pseudoscience or quackery. Finally, medical commentary is not to be construed in any way as medical advice.

To contact Orac: [email protected]

28 replies on “Falsus in uno, falsus in omnibus: A legal, not scientific, principle and example of dichotomous thinking”

One of my “favorite” examples of falsus in uno, falsus in omnibus is the invoking of pharma failings to damn vaccination.

Since there have been drug company scandals in the past (the case of Vioxx is most often invoked), we are to think that vaccines are bad and should be avoided.

I have responded to this argument by asking if diabetics should stay away from insulin, those with serious infections should refuse antibiotics and people with impending strokes are obliged to decline clot-busting drugs, since, y’know, pharma has done bad things.

No rational response is ever forthcoming. The usual comeback is…


Here’s a comment that was posted on a CBC article about a former politician supporting homeopathy:

Homeopathy, like traditional medicine, works for some people. For crying out lod we know that prozac didn’t work as well as placebos in clinical trials – what’s the big deal? Well, the CBC does support big Pharma and continues to push flu and measles vaccines and the fluoridation of water – all of which defy the lessons that we have learned from the science. But after facing scores of lawsuits for the damage caused by the opioid crisis the Pharma industry does need the vaccine money.

The scientific literature is littered with papers whose results were later shown to be either incorrect, mostly incorrect, or only partially correct.

Science is fundamentally different from the courtroom because the subject a scientist examines and reports on is basically a total unknown (from a fundamental science perspective). Nobody but that initial observer has seen it before; if people are error prone just as a function of being people, that initial report is subject to unpredictable flaws not because the scientist lied, but because that person may not have seen it or measured it quite correctly to begin with. And, with an initial observation, the rest of the field can only criticize the methodology by which the observation was made, rather than the actual veracity of the observation, until someone else goes and makes a supporting observation. You can basically always assume that the first observation has low resolution in some way.

That’s why cherry picking is so destructively misleading. Some sort of consensus is needed to fret out how much of any given frontier paper is truly correct. Applying Falsus in uno, falsus in omnibus to science fundamentally undercuts the ability for science to see new, previously unknown things.

Shouldn’t the falsus in uno, falsus in omnibus be applied to, for example, Andrew Wakefield? There is no doubt that he is a person of little to no ethics.

Another key difference is that Wakefield is one person, and the falsus in uno standard makes some sense when you are dealing with individuals.

In this regard Wakefield is like Jan Hendrik Schön, to take an infamous example from physics. Schön was caught fabricating data in one paper, so it became reasonable to investigate whether he had fabricated data in other papers–which turned out to be the case. But even the conclusions in his papers that turned out to be correct had to be investigated independently, because other scientists could not trust without independent verification that the results were true, and even with papers where he was not proven to have fabricated data, there remains the suspicion that he did and got away with it in that instance. That scandal is estimated to have set back his particular branch of solid state physics back by at least several years, and was a factor in the closure of Bell Labs, which had been regarded as one of the world’s top physics shops prior to the scandal.

Edward Jenner, who discovered inoculation with cowpox pus was an effective way to prevent smallpox.

[apologies if you already knew that]

@ Panacea:

No problem. But I’m glad that you self-identified.

As you may know, several people who comment regularly at RI also say that.
Here’s my big reveal:
if you ( or they) didn’t tell me, I would have never guessed AND I am someone who studied how people differ in abilities, what testing looks at, how people communicate in differing ways, writing skills and other achievements.

I also find it insulting that some trolls dismiss the spectrum as being mostly people with serious disabilities and a few odd geniuses ( or fictional characters) who excel. It’s a way to showcase their hatred of vaccines which they believe cause the ( fictional) damage by misleading readers.
People who study cognition and individual difference know that amongst groups of people – including NTs- people vary in multiple skills: e.g. some are adept at learning languages, some fail miserably; some have variable skills in imagery and visual memory, skills in mathematics are well-known to be diverse. Then, there are more arcane but important measures like field independence and social cognition skills.
A spectrum means diverse and variable.

I thought I’d mentioned it. Either I’ve lost track or I have unrealistic expectations given I come and go as a commenter 😉

But I try to be on my guard and avoid the black and white thinking (no pun intended) that I’m prone to because I know it irritates Orac 😉

But the part you said about cognition . . . nicely put 🙂

It’s also a double standard. Because they ignore glaring issues things like chelation or homeopathy have.

By the way, even in law a slight inaccuracy wouldn’t usually completely undermine a testimony, though a lawyer can present it that way. For example, it’s completely normal for honest witnesses to get dates wrong, occasionally.

it’s completely normal for honest witnesses to get dates wrong

As an exercise, try to recall what you were doing the last 29th of February.

An extreme case may have happened in the Courrier de Lyon case. According to one TV retelling, one witness was dismissed because she couldn’t recall the exact date of meeting one of the accused without prompting.
The case happened shortly after we French adopted the Republican Calendar, and the witness, barely literate, like maybe three-quarter of the population at the time, was evidently still not used to the new calendar and its slightly challenging base-10 system.
The message from the movie, is that, if only the judge had allowed the witness to corroborate the date using the old calendar, or some other dating system she was more familiar with…

I would point out that in modern time, a competent lawyer would help the witness prepare, and on dates too, and this would be raised in deposition and can be fixed. But still, any new question could raise issues.

It’s just not usually the case that one mistake can negate a lot of supported facts in most cases.

When great scientific theories fall, they do so of many grievous wounds followed by a rethinking of the total picture. And even then the old theory is often still of some utility if its limitations are recognised. That happened when classical physics gave way to quantum physics. They had the Ultraviolet Catastrophe, where Lord Rayleigh and James Jeans tried to derive a formula for blackbody radiation using the principles of classical electromagnetic theory and came up with a formula that was hopelessly incorrect, as it predicted that all heated bodies should emit radiation at an infinite rate. Ernest Rutherford found that atoms had a small, positively-charged nucleus, so it was thought that the electrons must be orbiting it. But that ran against the other fact from classical electromagnetic theory that said that any charged particle that experiences acceleration (as all orbiting bodies do) must emit radiation and lose energy that way, so it predicted that rather than being stable, the electrons would instead spiral into the nucleus. There were many more failures of classical physics and these led Max Planck, Niels Bohr, Albert Einstein and many of the other great physicists of the last century to develop quantum theory.

Does that completely invalidate classical physics? No! We still use Newton’s equations to calculate the motion of baseballs, cars, and even spacecraft. We still use Maxwell’s Equations to calculate the performance of electric motors, generators, and electric power systems. Even though we know that all these formulas are technically “incorrect”. You’d not use the Schrödinger wave equation to calculate the motion of a baseball or quantum electrodynamics to determine how much electricity you’d expect from a large electric motor. Newton and Maxwell are correct enough within the limits of those problems.

Falsus in uno, falsus in omnibus cannot and should not be applied to science. Just because Newton’s formulas are false when applied to the motion of an electron in an atom, doesn’t mean that the whole edifice of classical physics is totally wrong. Isaac Asimov’s essay on the relativity of wrong is particularly appropriate:

Is there a name for the reverse logical error? Recently, in response to a blog post on the unreliability of research coming out of China, a commenter tried to dismiss this by giving an instance of excellent research coming out of China.

That would be a non sequitur (loosely: does not follow). I have no reason to doubt that much of the research coming out of China is unreliable, and in many cases should be viewed skeptically. It will, and has, turned out that some of that Chinese research really is high-quality stuff, but the fact that some Chinese research is high quality does not imply all of it is.

China, like most large countries, has many universities that range widely in quality. I can vouch from firsthand knowledge that, at least in my field, Peking University and the University of Science and Technology of China are top rate. There are undoubtedly others, for which I do not have firsthand experience, that are top rate in other fields. But there are many second- and third-tier universities in China, and one has to be considerably more careful about trusting the results from an unfamiliar research group.

2 + 2 = 4
3 + 3 = 7

You must now accept both the truth and falsity of everything I say. I am a short alphabetic paradox.

If you lie about Chicago style pizza, you’ll lie about public transportation. Those Romans were way ahead of their time.

Describing Chicago style pizza being more like a casserole is not a lie. Though I do enjoy a well prepared double crust spinach pizza. Of course the well prepared one is prepared by me. 😉

Nov 2019: they announce that over 19 million USD will be given to fund 7 research projects ( I recognise a few of the names) to study indicators of autism that occur in the first year of life.
They include studies of eye gaze patterns and the earliest beginnings of social interaction of infants’ first few months.

Anti-vaxxers like Rossi and Wright despise this work, as they do genetic research, because it invalidates a great deal of anti-vax theory and their reportage of devastation of children’s brains following later vaccines.
I suppose they’ll have to now attack vaccines given around the time of birth or during pregnancy ( although that may point to prenatal causation which DOES occur though not because of vaccines)

Mrs Frisby and the Rats of?

(Just looked this up and oh my goodness, yes it is the same NIMH! That’s super weird and I think my brain just slightly slipped a gear. I’m going to have to go back and re-read that book.)

This is an awesome lesson in critical thinking and I’m passing it on to all the older grandchildren. I think it’s going to help me with my seemingly frequent encounters with cranks.

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