The truth...we may never find it

David Hume (1739) summed it up very well I believe:

"Thus not only our reason fails us in the discovery of the ultimate connexion of causes and effects, but even after experience has inform'd us of their constant conjunction, 'tis impossible for us to satisfy ourselves by our reason, why we shou'd extend that experience beyond those particular instances, which have fallen under our observation. We suppose, but are never able to prove, that there must be a resemblance betwixt those objects, of which we have had experience, and those which lie beyond the reach of our discovery."

We live in a time and culture in which the people involved in the brain tumor cluster in McCullum Lake may never know the absolute truth regarding this issue. I say this because the techniques and purposes of law and science differ dramatically. Both seek to find the truth, but each applies a different meaning of "truth".

According to L.O. Gostin, Public Health Law...Power..Duty..Restraint, "While law seeks finality and closure, scientific inquiry is continuous; while law in civil litigation makes decisions by the preponderance of evidence (greater than 50 percent), science uses statistical significance (greater than 95 percent, with a confidence limit that does not include 1.0); while law follows an adversarial method, science embraces the experimental design (the "scientific" method); while legal evidence is testimonial, scientific evidence is empirical. These different understandings do not mean that one field discovers truth and the other less than truth. Rather, the two fields have different missions and each operates, at least partly, in the other's environment. Science and law, therefore, must seek to understand the other, and each must accommodate the methods and cognitive processes of the other."

Conflicts and differences of opinion can occur between law and science in several areas; one area is that of the issue of causality - did an event or exposure to a substance produce or cause a certain harm to an individual or group of individuals. The plaintiff attorney tries to assign responsibility for the alleged harm to the defendant; that is his/her mission. The attorney for the plaintiff claim that a certain substance or substances caused a detrimental health condition to the plaintiffs. Sometimes this allegation takes place years or even decades after the alleged exposure to the alleged agent.

Problems arise in trying to prove scientifically that the alleged exposure to the alleged agent was directly and causally related to the detrimental health condition. Why? ...because of the number of individuals involved, the time span between the alleged event and the detrimental health condition and the many variables that might have or could have affected each of the plaintiffs over the many years since the alleged event and the detrimental health condition.

According to L. O. Gostin, Public Health Law...Power.Duty.Restraint, the "plaintiffs in exposure litigation must establish two types of causation: general and specific. General causation assesses whether the substance is capable of causing the harm found in increased levels in the population. Specific causation assesses whether exposure to the substance in fact caused caused the plaintiffs' harm." It can rarely be proven that the harm in the population or individual was directly caused by a specific event or substance which that population may or may not have been exposed to many years ago.

The epigraph by David Hume states that positive correlations never establish causation; however epidemiologists use statistical significance to establish positive correlations between two events, the exposure and the harm done, to support causality. But to do this by using the scientific method the causality is assumed only if there exists more than a 95 percent chance that the exposure results in harm.

This is the conundrum that exists in proving causation by using the law and using the scientific method.