All Men Are Mortal: Using Logic to Your Advantage

Discriminate between inductive and deductive reasoning; that is, be aware when an argument is being made from the particular to the general or from the general to the particular.

One of the most difficult things involved in analyzing claims is the difference between inductive and deductive reasoning.  Many of us remember the most basic form of deductive reasoning in the form of the classic syllogism presented in high school and college composition classes:

  1. All men are mortal.
  2. Socrates is a man.
  3. Therefore, Socrates is mortal.

The essence of deductive reasoning is starting with a general premise or hypothesis and using specific or particular examples to reach a conclusion.  An example in the medico-legal world is the general consensus that keyboard use does not cause or aggravate carpal tunnel syndrome.  This would be a general premise.  To support our argument we would then cite the relevant medical literature that demonstrates the correlation between keyboard use and carpal tunnel syndrome symptoms is coincidental and not causal.  We would also want to cite the relevant medical literature demonstrating the types of motions and forces necessary to cause carpal tunnel syndrome.  In addition, we would cite to medical literature demonstrating common risk factors for developing idiopathic carpal tunnel syndrome.  Finally, we would conclude that in our case the employee’s carpal tunnel syndrome bears no relationship to her employment because her keyboarding could not have caused the carpal tunnel syndrome, her other job duties do not involve the type of repetitive motions or forces that would be necessary to cause or aggravate the carpal tunnel syndrome, and that she demonstrates X number of factors that predispose her to idiopathic carpal tunnel syndrome. 

Inductive reasoning is the opposite:  we take many specific instances to reach a general conclusion or hypothesis.  For example, when an IME doctor says something to the effect of, “I have performed 10,000 total knee replacements and I have never seen osteoarthritis of the knee caused or aggravated by standing,” the doctor is engaged in inductive reasoning.  Likewise, all peer-reviewed, randomized, controlled medical studies use inductive reasoning because they measure the effects of individual outcomes in test and control group subjects and draw general conclusions therefrom.

In one of the more famous clinical trials, Kirkley, et al. concluded that using arthroscopy to treat osteoarthritis of the knee produced no better outcomes than treating the condition with physical therapy and medical management alone.  To reach this conclusion, the researchers randomly assigned patients with osteoarthritis of the knee to two groups, one which received arthroscopy, optimized physical therapy, and medical management and the other (control) group which received optimized physical therapy and medical management alone.  The researchers ensured that the subjects in each group were sufficiently similar so that unrelated factors (large bucket handle meniscus tears, extreme varus or valgus alignment) would not influence the outcomes.  Blinded nurses then followed both groups to measure the outcomes in each (patients in both groups wore neoprene knee sleeves so the nurses could not tell which persons had arthroscopy and which did not).  The researchers measured the results and found that there was no difference between the two groups with respect to physical function, pain, or health-related quality of life at 6, 12, 18, and 24 month intervals.  Based on the findings, the researchers concluded that “arthroscopic surgery provides no additional benefit to optimized physical therapy for the treatment of osteoarthritis of the knee.”

The question for us is how to apply this to the world of medico-legal claims.  Much of what we do when we analyze claims is inductive reasoning.  We look at particular behavior and argue that the claimant is not credible because he did X, Y, and Z, suggesting he isn’t being honest.  The hidden premise is that when we have observed others doing X, Y, and Z, we have found that they were being dishonest.  In order for inductive reasoning to be sound, we have to be able to demonstrate that the claimant in our case is sufficiently similar to the claimants in other cases that comprise the sample against which we are comparing our claimant in order for the conclusion to be valid.  Perhaps the X in our claimant’s case is employees who claim they were injured on a Friday while at work but do not report it until the following Monday.  In general, this fact pattern may suggest a credibility problem.  However, what if our claimant was a salesperson not expected to report to the office until Monday who was leaving after making his last call for the day who slipped while leaving the client’s house and suffered a head injury that required him to be transferred by EMS to a hospital.  Would this employee’s failure to report the injury on Friday still be a red flag regarding his credibility or honesty?

The point is that for inductive reasoning to be persuasive and accurate, it needs to be concrete and consistent.  Change the sample or the instance to which you are comparing it and the argument becomes less persuasive.  When analyzing a claim it is critical to recognize when you are using inductive reasoning to reach a conclusion so you can determine if there is actual evidence that supports your reasoning or if your conclusion is based on shaky assumptions about either the sample or the particular instance.

In essence, claims often involve a dance of inductive and deductive reasoning.  We frequently use inductive reasoning techniques to establish the minor premise of our deductive argument.  Let’s return to the carpal tunnel syndrome example.  We know that keyboarding does not cause carpal tunnel syndrome.  This is our general premise.  We also know what types of forces have been proven to cause carpal tunnel syndrome.  Our job, if we represent the employer, is to demonstrate that that claimant’s chief occupational exposure is through keyboarding and that she does not engage in other occupational activities that are known to cause carpal tunnel syndrome.  This is our minor premise.  Establishing that our claimant fits into the minor premise is an inductive process.  We gather all relevant information available to us:  job description, job video analysis, recorded statement, witness statements, etc. to demonstrate what the claimant does in her job to the highest degree of probability possible.  Then we make the inductive leap and state that the claimant engages primarily in keyboarding and does not engage in any occupational activities known to cause carpal tunnel syndrome.  We are then able to argue to the ALJ that the claimant’s carpal tunnel syndrome is not work-related based on the medical consensus that keyboarding does not cause carpal tunnel syndrome because her only occupational exposure is keyboarding.  We might also wish to gather evidence that the claimant has characteristics common to those who develop idiopathic carpal tunnel syndrome to be able to provide the ALJ with an explanation for why she developed carpal tunnel syndrome, though strictly speaking this is not necessary to our deductive argument.   

In this way, we integrate inductive and deductive reasoning to establish a strong argument.  The key, though, is to understand when we are engaging in each type of reasoning so that we are gathering the appropriate evidence for each type of reasoning.  If we understand this our reasoning will be sound and persuasive and we will be more effective in administering claims.  

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