Geology and the scientific method

The following item was originally posted in February 2007. I have added it to my blog recycling program. Because I have new readers of The GeoChristian, I will occasionally go back and re-use some of my favorite blog entries (sometimes with a little editing).

We often hear about “the scientific method.” It would be better to talk about “scientific methods,” because not all scientific problems can be approached in the same way.

Here’s a quote from geologist John D. Winter on how geologists think as they go about their scientific investigations:

Geology is often plagued by the problem of inaccessibility. Geological observers really see only a tiny fraction of the rocks that compose the Earth. Uplift and erosion exposes some deep-seated rocks, whereas others are delivered as xenoliths in magma, but their exact place of origin is vague at best. As a result, a large proportion of our information about the Earth is indirect, coming from melts of subsurface material, geophysical studies, or experiments conducted at elevated temperatures and pressures.

The problem of inaccessibility has a temporal aspect as well. Most Earth processes are exceedingly slow. As a result, we seldom are blessed with the opportunity of observing even surface processes at rates that lend themselves to ready interpretation (volcanism is a rare exception for petrologists). In most other sciences, theories can be tested by experiment. In geology, as a rule, our experiment has run to its present state and is impossible to reproduce. Our common technique is to observe the results and infer what the experiment was. Most of our work is thus inferential and deductive. Rather than being repulsed by this aspect of our work, I believe most geologists are attracted by it.

Winter, J.D., 2001, An Introduction to Igneous and Metamorphic Petrology, p. xvii. (bold emphasis added)

My thoughts:

  • There is not just one “scientific method.” Even in the experimental sciences, not everything is done in the strict order of Observation — Hypothesis — Experiment — Conclusion. Geologists do experiments, but these are done to give insights into how the world works so we can better understand both the past and the present.
  • The scientific method as practiced by geologists is often more like the work done by a forensic detective, trial lawyer, or historian. We have pieces of evidence, and we try to put together a coherent story about what has happened in the past.
  • This does not mean that geologists aren’t scientists. It just means that there are different sets of rules when one is investigating past, non-repeatable occurrences.
  • Almost all high school science textbooks have a section about the “scientific method” in the introductory chapter, presenting the standard Observation — Hypothesis — Experiment — Conclusion outline. This might be acceptable (though not completely accurate) in a chemistry or physics book, but it is downright misleading in an earth science textbook. I have not seen a single high school earth science textbook that points out these important differences in methodology.
  • This distinction comes into play in discussions about origins. When one is talking about earth history, evolution, or the origin of life, much of the discussion revolves around questions that can only be addressed by the historical scientific method rather than the experimental scientific method. This doesn’t make origins studies less scientific.

Grace and Peace