The problem of the Decline Effect

Most scientists understand today that scientific fact is never absolutely certain.  One reason is that a new theory might always displace an earlier theory, which then puts everything we thought we “knew” into a different perspective.  And indeed this has happened more than once in the last four centuries.

Many non-scientists are unaware of just how fragile the “facts” of science often are, how often they change, and why.  An article published last month in the New Yorker magazine explores one of the factors creating this uncertainty that until now most of us scientists have not fully appreciated.

The article is about what is called the “Decline Effect.”  Fundamentally, this is a phenomenon in which scientific findings get progressively weaker as they are repeated over time in new studies of the same phenomenon.  The effects of a new generation of anti-psychotic drugs, for instance, which twenty years ago seemed to reduce psychotic symptoms dramatically, have, bit by bit, begun to dribble away.

The Decline Effect, though, has not just appeared in relation to research into the effectiveness of new drugs and medicines.  It has shown up in psychology, in biology, in physics, in fact in almost every area of science.

What is going on?  Probably several different things are causing this disturbing phenomenon.  I will examine four of them in my following posts here.  And then, in light of its inescapable uncertainties, address the questions of science itself:  is it a valid source of information?  is it any better than intuition?  or even just a good guess?


About Terry Sissons

Terry Sissons is the author of The Big Bang to Now: All of Time in Six Chunks, and this blog is a dialogue about the universe and what’s happened in the last 13 billions years.
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