Tag Archive | hypothesis testing

Can you falsify an earth science hypothesis?

Answer: No.  Read on for why.

Science, they tell us in grade school and middle school and high school and often into college, has four simple steps: Observe, formulate a hypothesis, test that hypothesis, reject or accept that hypotheses (usually testing against a null). In this model, hypotheses should be falsifiable.  Is this done in earth science?

Consider the big mountain building hypothesis of the late 19th and early 20th century: geosynclinal theory. The idea was that parts of the earth’s crust would warp down, accumulate a lot of sediment, heat up and get injected with magma and deformed by thrust faults and rise up to be mountains.  One side was continental (the miogeosyncline) and the other we’d now consider to be oceanic (the eugeosyncline). Lots of embarrassing problems emerged: among them, fossils from one part of the geosyncline were totally different from those elsewhere in the geosyncline, so magical barriers had to be made (various flavors of eugeanticlines). Arguably many of these demonstrated that the theory was wrong, but instead scientists proposed ways that the theory could still be right.  It isn’t until plate tectonics overcame the objections to its predecessor of continental drift that geosynclinal theory was abandoned. It took a theory to kill a theory.

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Bad Apples, Picked Cherries and Trees in Forests….

One of the great challenges earth scientists face is knowing when observations refute a hypothesis, when they support a hypothesis and when they are nearly irrelevant. For instance, Alfred Wegener’s argument for continental drift made prominent mention of his geodetic measurements of the opening of the Atlantic. These were quickly found to be in error, throwing considerable cold water on continental drift even though many other arguments that Wegener made were quite sound. Obviously in this case it was a modification of the theory that was required, not outright rejection. This is a case of one bad apple that doesn’t spoil the whole barrel.

On the other hand, sometimes a theory is presented that explains one piece of evidence (usually the evidence that author collected) but ignores other information (several mass extinction hypotheses seem to fall into this category). While this happens in the scientific community, the most extreme cherry-picking comes from outsiders who find some curiosity that, to them, overturns all of earth science (creation science museums are full of such trivialities).

While lab science is often akin to a U.S. criminal trial (where guilt must be proven beyond a reasonable doubt), field science is more like a civil trial (where preponderance of evidence determines a victor). This is because there are a host of other variables in play. In fact it is quite rare for a single contrary observation to bring down a theory that has any real breadth.

Consider the “flat slab” hypothesis for the Laramide orogeny that created the Southern Rocky Mountains between about 75 and 45 million years ago. Read More…