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

5 thoughts on “Geology and the scientific method

  1. geochristian


    I have run into YECs who view geology as an inferior science because it works with historical methods rather than the “scientific method.”


  2. As a YEC, I’d like to make some comments.

    First of all, I think that this doesn’t make geology less scientific. It does, however, make the results of geology less epistemologically compelling. What makes physical science epistemologically compelling is that if someone has a different idea, the processes involved are usually generally amenable to set up the experiment in many different ways. We can see the variables, and we can map out, with precision, precisely how each variable fits. Likewise, every skeptic has the ability to rerun the experiment with different variables changed. Even with all of this, this does not guarantee the validity of the resulting theories and laws, but it does mean that, at minimum, the problem and solution are well-defined and well-tested.

    However, with sciences that are more forensic in character, such tamperings with the process are not available. Therefore, we are dealing with circumstantial, not experimental, data. Circumstantial data should not be ignored, but it is much less epistemologically compelling for a definitive conclusion.

    A lot of people (I think Mayr was in this camp), while they admit the differences in the methodologies between experimental and forensic approaches, don’t realize the epistemological restrictions this places on them. It is fine to operate a science this way, but only if the difficulties in doing so are honestly handled.

    If it is true that post-hoc circumstantial data is all that is available to geology, then one also has to admit the massive limitation this makes in any compelling case that one tries to establish from it. Every methodology has its pros and cons. The problem is that many who engage in forensic-type activities try to place upon it the same weight that experimental approaches have. Just because experimental approaches aren’t available is not a valid reason for arbitrarily increasing the certainty of other methods of inquiry. It just doesn’t follow.

    In my own case, I think that forensic methods are not the only ones we have. We have an additional set of accounts – written reports of historical incidents. I believe that observation is to be taken over circumstantial evidence. The written evidence from nearly every culture in the whole world is that there was a flood that drowned nearly all of humanity. Therefore, I think it is more appropriate to interpret the circumstantial evidence in light of the written reports, instead of taking the circumstantial evidence as more forceful, and then interpreting the written reports in the context of what we think the circumstantial evidence says.

    In summary, you can’t automatically upgrade the epistemological status of a methodology just because more reliable methodologies aren’t available.


  3. Jay C.

    Nice quote. This would fit nicely into my Powerpoint talk I’m giving this month entitled, “Evolution, but is it Science?” It shows the difference between the empirical and forensic sciences. I quote a forensic scientist who would agree with Winter that Historical Geology, Paleontology and Biological Evolution are all forensic sciences, because all their activity occurred in the past and are unrepeatable today. Thanks for recycling this quote. If I credit your blog, may I use it?


  4. geochristian

    Jay C:

    Go for it.

    It is the nicest summary of the difference between the experimental and historical sciences I’ve seen in a textbook. I have never seen anything even remotely like it in an introductory or high school text.


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