The Peculiar Logic of Scientific Knowledge

Understanding the role of negative results is crucial to an intelligent appreciation and application of scientific knowledge.  The amount of mischief caused by the belief that science can “prove” the truth of some statement has been incalculable, as the role of science in public policy has increased in recent decades.  No conclusion drawn from scientific research is ever absolutely certain.  It can’t be because, built into the deepest logic of the scientific method, is the strange fact that we can only be certain of what is not true.  There is no way that I can make a completely convincing argument for these assertions in the space of 1000 words.  Yet it is so important to understanding knowledge based on science, that I’ll try to outline the logic.

When people say, “This is based on science,” they are referring to some general statement, a principle or theory that applies to all instances.  In Jennifer Rohn’s story (see my previous post for a review of The Honest Look) the Universal Aggregation Principle on which the Neurosys company was founded is called “universal” for a very good reason.  It is a general statement about the way certain proteins clump together outside brain cells in Alzheimer’s disease.  Its authors, the company’s founders, claim that it is true, not only in mouse brains where it was first studied, but also in the brains of humans with the disease.

When Claire discovers that the General Aggregation Principle isn’t completely general, the company’s key claim is “proven” false.  Science advances by gradually ruling out an endless parade of general assertions, narrowing and honing the details of general principles that have survived the scrutiny of many experiments or observations under a wide range of conditions, until eventually most people who understand what’s going on are convinced.  That consensus never rules out future negative findings and further revisions of important theories.  And there have many shifts in the consensus of specialists with regard to theories.  In 1900, almost no physicist had heard of the theory of relativity and few geologists would have taken the theory of plate tectonics seriously.  Today, it would be exceedingly difficult to find one who does not.

Jennifer Rohn’s account of Claire’s reaction to her accidental finding brings out several other important aspects of scientific logic.  First, disbelief.  How could her finding be true?  Everything she knows says it can’t be.  Second, replication.  It must be a fluke.  She repeats it “…twice, ten times, and then a hundred times…” (THL, p. 99).  Third, vary the conditions.  Maybe the negative finding is limited in scope.  She samples different regions outside the cell wall.  Fourth, maybe her experiment is different in an important way from the earlier ones.  She goes back and samples the intracellular fluid from mouse brains.

Then, she asks for another human brain.  (More replication.)  Maybe her first brain was an exception or atypical in some important way.  Finally, she tries a different line of explanation, one that’s consistent with her finding.  What if the company’s drug works by some other mechanism?  And she casts about for a different kind of evidence having to do with other molecules involved with the key proteins.

At some point the weight of evidence shifts.  The Aggregation Principle isn’t universal at all.  What are the implications, especially the practical medical and business ones, of believing the crucial principle is false?  Jennifer Rohn’s novel beautifully captures on a small, easily understood human scale, the controversies in science over the interpretation and application of new findings and theories.  I’ll leave you to experience this for yourself from reading this delightful novel!

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