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Monday, September 25, 2006

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Fingerprinting: A Revolution in Cracking Crime PETERBOROUGH EVENING TELEGRAPH, UK - Sep 21, 2006 ...latest digital technology will be brought in to speed up the fingerprint process...

New Crime Lab Helps Track Suspects  WKRC-TV, OH - Sep 19, 2006 ...fingerprints from arrestees are now entered into a local database to compare with prints left at crime scenes...

Victim Blasts Cops for Delay INDEPENDENT ONLINE, SO AFRICA - Sep 19, 2006 ...victims had to wait for nearly 48 hours before detectives and fingerprint experts arrived...

Fingering Criminals FT WORTH STAR TELEGRAPH, TX - Sep 17, 2006 ...fingerprints inked onto bad checks are searched through an AFIS database...

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No major updates on the website this week


Last week

Frank Fitzpatrick gives us a look at the FQS-I Police Science Accreditation Program

This week

we take a look at Part I of a two-part speech by Steve Scarborough on "Leaps of Logic" and "False Dilemmas".


Infallible - Part I
by Steve Scarborough

Addressing a large audience of latent print examiners)

Good Morning Ladies and Gentlemen,

Today we are going to discuss a number of issues with regard to the uniqueness of Fingerprints1 and hopefully you will gain benefit from seeing another side to some of today's most heated fingerprint-related issues, while pondering some different and thoughtful perspectives. Many fingerprint experts see that challenges are good for the discipline; that challenge help us think about some issues that some would just prefer to let pass by. We are often too busy with our daily casework of making comparisons, processing crime scenes and catching criminals to ponder some of these often theoretical thoughts about Forensics.

      There is the hypothetical and theoretical side of certain issues vs. the practicality of our daily work, something we will discuss later in today’s presentation. However, if there is value in some of these challenges, we should be appalled at the more outrageous claims by the very tiny handful of critics.

Right now though let’s look at this headline: 

: Medicine in shambles. People refuse to go to Doctors for Treatment! A study shows that doctors make mistakes in diagnosis.

I am going to show you a few more headlines throughout this presentation to make a point.

we are going to discuss various ways to look at just 8 issues about fingerprints, though I know there are more bouncing around out there. We all know that there are a lot of ways to look at an issue and usually none of the perspectives are wrong but some are not very logical. I won’t say that any perspective is the only correct one, but I will provide some logical or empirical data for certain points of view.

     First, though, let’s get a perspective on the issue of uniqueness. The science behind the uniqueness of fingerprints and specifically the random creation of friction ridge skin is solid. The statement: Fingerprints are (absolute and) infallible, you must remember, is in response to a challenge that Fingerprints are not unique. And claims like- “we haven’t seen all the fingerprints in the world or in history” or “there hasn’t been enough research to show that they are unique.”

     The “infallible” statement is not meant to address the issue that fingerprint experts may make mistakes. That emphasis or new meaning to the phrase came much later in an attempt to promote a separate agenda. In other words the statement is solid in its original context and the emphasis was changed by someone as a leap of logic.

      So don’t forget now, the context of the strong response statement “Fingerprints are infallible” is in reaction to the challenge “that fingerprints are not unique (and therefore should not be used to individualize to a person.)”  This statement is in the context of the challenge that fingerprints are Not unique therefore it is entirely appropriate in this form. Perhaps a better word than infallible could have been used, absolute, unique, reliable …but the context has nothing to do with the human imperfection of making a mistake.

     Look at the statement here: “Fingerprints are infallible.” Now here is the leap: “So you can’t make a mistake then?” Stop laughing for a second and you can see how the two concepts do not go together.  

Here is another headline.

: Flaws in Radiology! X-Ray machines are not accurate. “X-Rays should not be used,” says California university professor.  Interpretations of x-rays have shown mistakes.

     We have seen a lot of bold headlines to various stories lately. Some of which, if the story is read diligently, can be scrutinized to show that the headline is not supported by the facts of the article.  Of course that is not at all that unusual in journalism. The object is to catch the eye of the reader. I am sure you can remember some of those you have read. 

     Now why show you these headlines?  To point out that leaps of logic are occurring here. These headlines I am showing you are leaps of logic without any substance. Much like the challenge statements that have been posed about the validity and reliability of Fingerprints.

For instance here are some of the headlines we have seen about Fingerprints lately.


The Myth of Fingerprint Science Revealed!

How Far Should Fingerprints Be Trusted?

Fingerprints are Not Infallible Evidence.

Are Fingerprints Really Infallible, Unique ID?

Unproven Forensic Techniques sway courts!

The Real Crime- 1,000 errors in fingerprint matching every year.

     A leap of logic is when the conclusion does not follow the supporting information. It is the opposite of the scientific method in operation.   It is my opinion that that is exactly what occurs in Simon Cole’s book, Suspect Identities. Extensive evidence is presented in the book to show that Fingerprints have been challenged in court, have been extensively researched, are currently being researched and studied, are reliable and are in fact unique. However, the author interjects his own conclusions that are the opposite of the evidence presented; resulting in confusing leaps of logic.

     Now why would some people make these leaps of logic? Why would they skew normal logic and ignore their own research? I will let the audience come up for the reasons behind this intentional ambiguity.

Which brings us to Leap of Logic #1 “There is nothing absolute in science”

Let’s explore a response to this statement.

      This is a great philosophical and theoretical expression that is well suited for think tanks and academia, but not for the practical world.  This is one of my favorites. In fact, in the practical world, it falls into one of the


“Nothing is absolute in science!”

Though this might be a good philosophical argument, in practicality it is a science myth.

Let’s look at some other science myths. No, there are really no alligators in the sewers of New York and these are also science myths:

“Humans use only 10 percent of their brains.”  An MRI of the brain shows that most all of the brain is put to use. 2

 “Water drains backwards in the Southern Hemisphere.” Just not true. You can see for yourself on your next trip south.

“Lightning never strikes the same place twice.” Not true, lightning favors certain spots, particularly high locations.

“There is no gravity in space.” “Zero-gravity” and space is a vacuum are more science myths. Gravity affects everything throughout space.

     Gravity is a very good example here because that is one of the major factors to mention to counteract the statement of “nothing is absolute.” Gravity is absolute! The recent NASA space probes used gravity for propulsion in the deepest space. In fact the term “zero gravity” is a misnomer. Gravity is absolute (infallible) and there are no two planets, fingerprints, plants, tigers and snowflakes that are exactly alike.

     If you think about it, this dogmatic approach is really anti-science. To even consider the possibility, from what we know of the random creation of all  of these objects, that any one of these things could have another randomly created object exactly the same flies in the face of scientific knowledge. In other words, to disregard all of the evidence that points to one conclusion and –just for the sake of the old myth- keep thinking of the possibly of a random duplication in nature.  

     If you ask the right questions of most of the scientist in these fields they will say that, in the practical world, no two snowflakes, no two trees, no two asteroids are alike; and that is the absolute.

A sub category of Leap of Logic #1 is the statement “even math is not absolute.”

     The argument follows that because a triangle cannot be created that is perfect, even math is not absolute. Another very theoretical statement, however, this is really referring to the human formation and drawing of the triangle –but the philosophical measurements are exact and absolute –so that just proves the point if created by “nature” or in random manner it can’t be exact –just like no two fingerprints are alike.

      Another thought that relates to this idea that is sometimes professed regarding Fingerprints is the following thought: “After all, every transfer of a fingerprint is distorted and not complete, so it is always different and difficult to categorize as a unique medium.” This statement actually mixes physical structure with interpretation –human intervention (nature) and therefore doesn’t change the fact that the original surface (skin) cannot be recreated and is unique.  Just because every impression is different doesn’t mitigate the fact that the friction ridge skin is still unique.

Hypothetical, philosophical and theoretical

     Obviously there are a number of issues about Fingerprint Science that can be discussed on a philosophical and theoretical level. This approach is absolutely appropriate for think tanks, academia and the published treatise. However, what the working fingerprint expert knows is that just doesn’t cut it in the real world. We have to be able to acknowledge that side of the issue; and then separate it from our practical work.

Next let’s look at:

LEAP OF LOGIC #2 “The FBI says that they don’t make mistakes”

      You might have heard this statement during a discussion about the infallibility of fingerprints. We already know it is a leap of logic to mix uniqueness of fingerprints with human mistakes but let’s look at this statement anyway:  “The FBI has always said and promoted that they do not make mistakes.”  Well this is patently untrue from most of our experience. And certainly not anything that is the official line of the FBI. I would guess that this leap derives from -interviewing some experts and lurking on the websites- hearing that the FBI has always presented an air of superiority. And also from a misinterpretation of very confident FBI court presentations regarding fingerprint IDs.  But that does not translate into “the FBI has always said that they are infallible.” 

     In all the training classes and presentations and testimony, the FBI has never once said that there are no mistakes made by fingerprint experts. In fact the FBI, in warnings about effective verification, mentions mistakes that they are run across in submitted cases from local agencies. The FBI has always promoted verification, consultation and double checks to assure that no mistakes in fingerprint identifications are made. The FBI has always based their high confidence of their fingerprint IDs on the infallibility of the science.

    The FBI instructors stress verification and other quality control measures.  They promote and teach verification to prevent mistakes. If people didn’t make mistakes with regard to Fingerprints (people are infallible) then we wouldn’t need verification.  But we all know that human beings make mistakes, and it goes without saying that humans are not infallible. The assumption that when the FBI fingerprint expert says that they are 100% certain about the ID, that they are implying that they don’t make mistakes, is a grand leap of logic.

:  Miscalculation made in Hubble Telescope. Entire sciences of astronomy & engineering called into question!

      If you look back at these headlines, not only are they leaps of logic, but some are also a false dichotomy or false dilemmas. While the statement, “he said that Fingerprints are infallible therefore he says he can’t make a mistake” is a laughable leap of logic, it is also a gross false dichotomy. A false dichotomy or false dilemma is a logical fallacy that supplies only one answer to a situation. Often used in propaganda, these statements try to lead you into a conclusion that is serves a purpose, implying there is only one conclusion, when there are always many conclusions to any situation.

      “You are either with us, or you are against us”. “If you vote for that protection law -they will just raise prices (rates).” "You're either part of the solution or part of the problem."  You may see how some of these leaps of logic do not account for other alternatives and are false dilemmas.

Leap of Logic #3, “After all that is what we have been saying for all this time” -

    Another thought being suggested is the idea that the fingerprint community has been saying all along that fingerprint experts don’t make mistakes. Well, in reality, what we have been saying is that this ID was achieved through extensive evaluation, it has been verified and we are 100 percent confident in the conclusion.  That doesn’t sound anything like the discipline has always said that they don’t make mistakes now does it?

     By stating, as we have over the last 100 years, that we are confident of an ID, it means just that, and it is obviously a leap of logic to twist that assertion to mean that we have always been saying that experts don’t make mistakes.

: Two Snowflakes Found to be Alike!

     This is actually part of a real article. It can be found on the Australian “great moments in science” website. There is an article entitled “Fingerprints Identical?” The article, written by Dr. Karl Knuszelnicki, is skeptical about the validity of Fingerprints. However, it reeks of leaps of logic. For instance, it states there were 22 mistakes of fingerprint identifications in the last 100 years, therefore that reverses the validity of Fingerprint Science. And the article arrives at the bizarre conclusion that because the IAI requires that conclusions must not have possible or likely results, therefore “they never admit to an error.” 3

     Within the article it mentions that “a scientist by the name of Nancy Kerry found two identical snowflakes in a Wisconsin snowstorm in 1988.” The implication is that snowflakes can be alike and so can fingerprints. However, the real story is that a scientist by the name of Nancy Knight observed two attached ice crystals that were “very similar if not identical.” (her words) 4  What seems to have happened is that it is unusual to have ice crystals even closely resemble each other, and that was an event in the world of atmospheric research. In actuality, when comparing the crystals with an eye for uniqueness, like a comparison expert does, the crystals are not at all alike. 5 

     Look at these photos of the crystals.6  They are similar but not exactly alike. You can see that this similar rarity of ice crystals actually reinforces the axiom that no two snowflakes are alike and pretty much shoots a hole in this “great moment in science.” Once you delve into the article you find that the headline isn’t true.  

Leap of Logic #4, Well that is what we have been taught

     Another thought or argument is that we have all been taught or trained that fingerprint experts cannot make a mistake. This seems to me to be another logic twist to information gleaned in interviews or internet lurking. In fact, just the opposite it true.

     Look at this statement: “Finally, we hope that fingerprint examiners will rethink their longstanding claim that competent examiners cannot make errors. Always wrong, this claim is now absurd. Like emperors caught without clothes, fingerprint examiners must now decide whether to acknowledge reality or continue their brazen pretense.” 7

     That statement is a huge leap of logic with plenty of skewed thinking. As fingerprint experts, we have been taught that the science of Fingerprints is exact, the methodology and biology supports that fact, but as a practitioner, a fingerprint comparison does have pitfalls and you have to prevent them the best you can.

     Many of us were not taught in just that language or rhetoric.  However, just like Ridgeology, we may not have been using the language, but it was a process we have been following from day one.  As fingerprint experts we have been taught that we must work to avoid mistakes.  We have always talked about mistakes and have never, ever, had conversations that there are no mistakes in fingerprints.  Almost every expert was taught in classes and by their trainers to prepare for questions about mistakes in court.

Remember that moot court question you are always asked? “Have you ever made a mistake?”  Does that sound like we have always been taught that fingerprint experts don’t make mistakes? Of course not!

     In training, and in our in moot courts, we were questioned about the importance of verification and what would happen if you made a mistake. Remember the old adage “If you make a bum ID that will pretty much end your career.”  Despite the hyperbole, it is obvious that statement means, not that there are never mistakes, but that an expert must take all the precautions to prevent them.

         Additionally as part of our training we have been taught about confirmation bias and pressure from DAs and detectives.  We were taught not to let that outside pressure effect your examination and to keep a clear head on those high profile/pressure comparisons.

We would never have been taught about these issues if at the same time we were being taught that it there were no mistakes in Fingerprints.

In training, our instructors show us the mistakes we made, so that we can try not to make them in actual casework.  The message has been: be very careful and have a through verification of all your IDs.  So obviously statement #4 is a tremendous leap of logic.

Why don't we take a little break at this point in time... let's try to be back in our seats in... say about 7 days from now. (*smile)

[we will continue next week with Part II - #5 through #8.]


1  The Detail, issue #174, Dec. 13, 2004, They Keep Putting Fingerprints in Print, S. Scarborough
2  Live Science,

3  great moments in science, , as reported by Dr. Karl Knuszelnicki; unsure of the original source of the other statements.

4 Original article in the Toronto Star, Dec. 17, 2005 by Jay Ingram, and the Wilson Bentley Newsletter Archives,

5 Earth & Sky,

6 Photos of ice crystals.

7 Column: Forensics: Lessons from the Brandon Mayfield Case, William C. Thompson; Simon A. Cole, Champion, April, 2005

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Until next Monday morning, don't work too hard or too little.

Have a GREAT week!