UPDATES ON CLPEX.com
No major updates on the website this week
we looked at Part I of a two-part speech by Steve Scarborough on "Leaps
of Logic" and "False Dilemmas".
we take a look at Part II.
Infallible - Part II
by Steve Scarborough
(Addressing a large audience of latent print examiners)
Welcome back from break, Ladies and Gentlemen,
We are continuing to discuss a number today's most
heated fingerprint-related issues while pondering some different and
thoughtful perspectives to gain benefit from seeing another side of the
Leap of Logic #5, “Isn’t that what you are saying by the statement of
That people can’t make mistakes? Well, no. That is not what anyone
is saying by the assertion of the infallibility of Fingerprints. Funny, but
that doesn’t happen in any other discipline or science. When an expert makes
a general statement about their science or discipline they are not referring
to the conclusions made by individuals in that area of expertise. Experts
make assertions, some very restrictive, about what happens in their
discipline to support their conclusions. In other words: due to gravity,
water drops to the lowest point. This statement is positive and solid –it is
not saying that an engineer never makes mistakes. When a hydrological
engineer says that the water invariably flows down that section of pipe and
is 100% confident that is how it works, that person is not saying that
engineers don’t make mistakes. It is a leap of logic to think that one
follows the other.
Now that I have armed you with the tools: leap of logic, false dichotomy&
false dilemma, intentional ambiguity, science myths and the ideas of context
and philosophical vs. practical discussions-
Let’s look at Karl Popper. Here is another perspective on Popper
and falsifiability. Karl Popper was a NOT a scientist, he was a
philosopher. 8 He wrote about
progress of science and scientific ideas. He was vastly concerned with the
social sciences, such as the ideas of Freud, and Marx and analytical
There are many scientists that do not agree with Popper. In fact,
Popper is and always has been surrounded by plenty of controversy.
Remember, Popper was a philosopher, not a bench scientist. Popper worked in
the abstract, the philosophical world. While his theories have merit in that
world, they really have little relationship to the practical world.
“Thomas Kuhn’s influential book The Structure of Scientific
Revolutions argued that scientists work in a series of paradigms and
found little evidence of scientists actually following a falsificationist
“Another objection is that it is not always possible to
demonstrate falsehood definitively, especially if one is using statistical
criteria to evaluate a null hypothesis. More generally, it is not always
clear that if evidence contradicts a hypothesis that this is a sign of flaws
in the hypothesis rather than of flaws in the evidence.”
10 However, one interesting stance
of Popper is that he “makes clear in the Logic of Scientific Discovery,
his belief that the resolution of conflicts between hypotheses and
observations can only be a matter of the judgment of scientists, in each
individual case.” 11
In the end, Popper’s falsifiability notion is a
perfect example of how a philosophical argument cannot always be used for
the practical world. These philosophical thoughts just don’t translate
effectively to every idea or science. Just like “error rates,” are best
suited for chemistry and machines, and should not be applied to a practical
or applied science. Falsifiability should not be applied to an observation
or applied science like Fingerprints.
Our next Leap of Logic is # 6, “The 100% sure statement reveals a problem in
Now wait a minute, this is a huge leap of logic. Confidence shows
a weakness? That doesn’t fit does it? And just like a lot of these other
statements, the two do not go together (false dichotomy) and show why this
is another leap. We have already busted the myth that “there is nothing
absolute in science” in the practical world, so it cannot follow that if you
say you are 100% sure about something that you are automatically incorrect.
Especially when the basis is the random creation of friction ridge skin.
That is a leap of logic into a false dichotomy.
Leap of Logic #7, “They cover up mistakes, so that shows that Fingerprints
are not reliable” -
If an organization is reluctant to admit or reveal mistakes it
doesn’t naturally follow that they are questioning the validity of what they
do. Generally, it just means they would rather not have their mistakes aired
in public. First, it certainly doesn’t mean that mistakes cannot be made
because, at least internally, they are admitting to a mistake. Second, it
generally doesn’t mean that they think that their people doing that
discipline are infallible. It is a leap of logic to think that if a mistake
is not publicly acknowledged by an agency, that it means that the entire
discipline thinks that mistakes cannot be made or that the process is not
Leap of Logic # 8, “Fingerprint experts make mistakes, therefore
Fingerprints are unreliable” -
Look at these statements:
“…the fingerprinting community has
attributed errors to incompetence, rather than to the inherent unreliability
of their craft, in order to maintain the pretense of infallibility in the
face of irrefutable evidence that misidentifications have occurred.”
12 Mistakes are made, therefore the
science is unreliable? Isn’t it obvious where the leap of logic is here?
Look again at that sentence. There are so many things wrong with that
sentence and its propositions it boggles the mind. Can you find all the
fallacies in that statement?
The fingerprint expert says, “Fingerprints are infallible”, the critic
hears “experts can’t make mistakes.” Conversely when the critic sees that an
expert made a mistake, the critic concludes that the science and methodology
are somehow flawed and that the process is inherently unreliable. Huge
leaps of logic that are unscientific, illogical, and frankly, should not be
looked upon as having any viable substance.
That is the purpose of the HEADLINES that I have been showing you.
These statements are controversial so they get the press, like the very
noticeable headline, “Two Snowflakes Found to be Alike!”- But it is easy to
see in the actual story that there is no substance to the boast.
Anytime the critic makes these leaps of logic and statements of false
dichotomy - one of us should be there to say - “NO, that is not what that
statement means." We should be there to say- "I know it serves your
personal purpose, to attempt to discredit Fingerprints, but that is not what
is said nor is it even implied or suggested." "You are wrong. Your
conclusion is mixing two concepts and it is a leap of logic."
Now for later, here is your assignment: look at each of these
statements, and the numbered assertions, and decide upon your perspective
and formulate your responses.
Oh and your future homework is this. Every time you hear someone make
one of these statements like: “You said Fingerprints are infallible so that
means that fingerprint experts don’t make mistakes” or “There is a zero
error rate for fingerprints so that means that fingerprint experts won’t
admit to making mistakes” or any one of the above statements; that you
challenge the person spouting them.
These approaches, when you examine them carefully, are really bizarre and
have no real merit. Don’t let them get away with it without a logical
response. Don’t let them get any momentum for their false dichotomy,
intentional ambiguity, or contextual twist. Stand up and affirm: “That
doesn’t make sense! Or: That thought is interesting but your conclusion
doesn’t follow. Or: That is a philosophical argument that isn’t relevant in
the practical world. Or: That is a bizarre and unscientific leap of logic!
Sounds familiar doesn’t it?
Column: Forensics: Lessons from the
Brandon Mayfield Case, William C.
Thompson; Simon A. Cole, Champion, April, 2005
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