All scientific disciplines share at least one commonality, they all utilize the scientific method.  All scientific inquiries start with observation, the first step of the scientific method.  The importance of the power of keen observation can never be over--emphasized. The second step of the scientific method involves forming a hypothesis in an attempt to describe that which was initially observed.  It is usually the case that the simplest, most straightforward hypothesis that involves the least amount of explanation or assumption is the correct one.  Contrary to popular belief, hypotheses should be more of a prediction than an “educated guess”.  The next step, and incidentally the one that is most often neglected in science, is to conduct a review of the literature.  Since scientific progress is a building process that starts with some sort of foundation, or prior work, it is necessary to determine if prior research conducted in this area has already addressed one's initial observation and/or hypothesis.  To put it simply, literature reviews keep scientists from constantly reinventing the wheel.  Interesting situations can come about at this stage because if someone has already addressed this topic, one can see if the hypothesis is similar or different from the one currently being pondered.  If someone has previously tested the hypothesis, then the necessary work has been done and you get an answer to your inquiry.  Since one fundamental aspect of science is that all research should be reproducible, one can make the decision at this point to repeat the published experiment or to go on to something novel.  Sometimes it is the case that the method or design of the experiment used to test the original hypothesis is either totally invalid or is deeply flawed at best.  Therefore one can design a new way to test the same hypothesis.  However, if after an extensive literature review one's own hypothesis has never been examined, the fourth step of the scientific method is to perform an experiment designed to directly test the hypothesis.  Sound experimental design is critical because if your method of testing is invalid, the results obtained from the experiment will be invalid.  Therefore, experimental design is as precious as the data collected for research.  The fifth step is to arrive at a conclusion based on the results obtained from experimental testing.  The final step in the scientific method is peer review.  This is necessary because the research project must stand up to criticism and meet all necessary standards of the science of the day.  Peer review can lead to publication of findings in the appropriate journal(s) of that particular field.  Since studies of friction ridges can conform to the scientific method, it is evident that fingerprint science can be regarded as a science.

It can be said that one of the intended goals of science is to determine proximate and ultimate causation and their effect.  Proximate causation looks at the mechanisms of causation and answers the “what” and “how” questions.  An example of this is “What causes fingerprint deposition?”  Of course our scientific knowledge of  fingerprints tells us that the components of perspiration are responsible for causing normal eccrine and apocrine fingerprint deposition.  “How” fingerprints are deposited forms the next aspect of proximate causation.  Science once again tells us that when an individual makes contact with an object with his/her hand, perspiration from the volar pad region is transferred from the person to that object.  In fact, anxiety and fear can increase the probability that a person will perspire and therefore deposit fingerprint marks.  All these examples show the proximate causation of fingerprint deposition.  Ultimate causation looks at “why” something is the way it is.  This type of inquiry is a favorite among evolutionary biologists.  For example, the ability to firmly grasp objects in our environment gave us a distinct advantage over other organisms that lacked epidermal ridges.  In the case of humans, those that possessed epidermal ridges had a greater chance of survival, hence a greater potential to reproduce and leave progeny than those that did not possess this trait.  Of course this has to be empirically proven for it to be valid in the eyes of science.  It is important to note that inquiries into ultimate causation rely on the foundation of proximate causation in order to fully explain “why.”  This is yet another example of how the study of fingerprints can conform to science.

Another facet of science is deductive and inductive reasoning.  Deductive reasoning is a process whereby a scientist infers by reason from a general premise to specific conclusion(s).  An example of this is when a fingerprint examiner has a large “pool” of suspect exemplars to compare with an unknown print and she/he conclusively matches the unknown print to a single suspect exemplar.  This is deductive reasoning due to the fact that it narrows the suspect pool of numerous individuals down to a single individual.  Inductive reasoning refers to the process in which a scientist begins with a specific conclusion and, from this conclusion, makes a general inference.  A good example of this is the assertion that there are no known cases of two individuals having matching fingerprints, therefore the general inference is that all fingerprints are unique.

Every scientific discipline has a paradigm, or central unifying theory, that explains the basis for the existence of scientific phenomena.  The paradigm of biology is the theory of natural selection.  Chemistry is based on atomic theory.  The theory of relativity is central dogma to physics.  Forensic science is based on Locard's principle.  It can be argued that the paradigm of fingerprint science is that all fingerprints are unique and that the spatial arrangement of epidermal ridge detail is permanent.  True science adheres to theories that are falsifiable.  In other words, theories must have the potential to be proven false.  Every time an examiner compares prints of different individuals, there is always the chance of falsifying the paradigm of fingerprint science.  The fact that no two people have identical fingerprints after over 100 years of fingerprint comparisons tends to strengthen and validate the paradigm of fingerprint science.  Usage of theories that are falsifiable is what separates true science from religion.  Science is based on acceptance of facts derived from inquiry and experimentation whereas religion is based on personal belief.  It is the material realm versus the spiritual realm.  The fact that personal beliefs cannot be falsified due to the fact they are based on subjective opinions is evidence that religion is not a science.  Another major criteria for science is that results gained from an experiment or test must be reproducible within an acceptable margin of error.  Without reproducibility there is no reliability.

As mentioned previously, science must be falsifiable in order to be separate from religion.  So what happens if a paradigm is eventually falsified, or proven wrong?  The answer is the theory is simply re--examined in order to determine how to accommodate the new finding.  This is known as a paradigm shift.  A classic example of this is when the germ theory of disease was eventually recognized by the established medical community.

It is obvious that fingerprint identification surpasses the criteria for being a true science yet much ink is still spilled in trying to defend it as such.  Relatively few areas of science can claim that their paradigm is based on absolute certainty.  Fingerprint science has that luxury.  If  a fingerprint examiner makes a conclusive identification, he/she must be 100% certain because that is both the theoretical and the real standard of a conclusive match.  Upon reflection, high school science teachers and university professors alike have instilled in all of us that nothing can be an absolute certainty in this world (even though, ironically, this is in itself an inherently absolute statement).  In the case of fingerprint ridge identification it looks as if they were wrong.

References:

Lee, H.C. and R.E. Gaensslen (eds.) Advances in Fingerprint Technology. CRC Press:Boca Raton, 1994.

Magner, L.N. A History of the Life Sciences.  Marcel Dekker, Inc.: New York, 1979.

McRoberts, A. “Is Friction Ridge Identification A Science?” The Print, 14(1) 1998. Pp 4--5.

(Editor--—While there has been a great deal of discussion about the merits of a Bachelor level degree requirement for latent print examiners, one thing is certain--—students seeking  degrees to pursue careers in Forensic Identification will provide a great deal in the way of literary discussion.  These discussions will benefit and advance our science.)

This article was printed in “THE PRINT”
Volume 14(4) July/August 1998, pp 4-5
and has been obtained from the online library provided by the
Southern California Association of Fingerprint Officers
www.scafo.org