Falsus in uno, falsus in omnibus: A legal, not scientific, principle and example of 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 Townhall.com 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.”