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15.5.2: Fruitful and Unfruitful Explanations

  • Page ID
    36302
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    Untestable explanations are avoided by good scientists, but fruitful explanations are highly valued. To appreciate this virtue of fruitfulness, consider the scientists' favorite explanation of what caused the demise of the dinosaurs 65 million years ago. Four explanations or specific theories have been proposed in the scientific literature: the sex theory, the drugs theory, the violence theory, and the crime theory.

    • Of all four theories, current science favors the violence theory. Why? There are two reasons: it has been successfully tested, and it has been fruitful. The other three theories are testable in principle, but they are too hard to test in practice. The soft parts of male dinosaurs don't leave fossils, so the sex theory cannot be tested by looking for fossil remains. The drug theory is too hard to test because nothing much is known about which drugs were in which plants so long ago. The crime theory is too hard to test because there is no practical way to check whether little mammals did or didn't steal the dinosaur eggs. On the other hand, the violence theory can be. Suppose a violent global event threw dust into the air, darkening the Earth, leading to cold weather and the end of most plant photosynthesis. Digging down to the 65-million-year layer should reveal a thin layer of dust, no matter where in the world the scientists dig down. And indeed, scientists have discovered a layer of dust there containing a high concentration of a very rare element, iridium. Although naturally scarce on the Earth's surface, the element is relatively abundant both in asteroids and deep inside volcanoes.

      In addition to its having stood up to this observational test, the violence theory is favored because it is so fruitful. That is, scientists can imagine many interesting and practical ways in which the theory can be tested. They can search satellite photos looking for 65-million-year-old asteroid craters. At suspected crater sites, they can analyze rocks for signs of impact—tiny fractures in shocked quartz. Digging might reveal pieces of an asteroid. A large speeding asteroid would ionize the surrounding air, making it as acidic as the acid in a car battery, so effects of this acidity might be discovered. Imagine what that rain would do to your car's paint. Scientists can also examine known asteroids and volcanoes for unusual concentrations of other chemical elements in addition to iridium. Ancient beaches can be unearthed to look for evidence of a huge tidal wave having hit them 65 million years ago. All these searches and examinations are under way today, and there has been much success in finding data consistent with the violence theory and little uncontested counterevidence.

      Thus, the violence theory is the leading contender for explaining the dinosaur extinctions not because the alternative explanations have been refuted but because of its being successfully tested (so far) and its being so fruitful.

      This brings us to the edge of a controversy about scientific methodology. The other alternative theories of dinosaur extinctions have not been refuted; they have not even been tested. But if they have not been refuted, and if proving the violence theory requires refuting all the alternative theories, doesn't it follow that the violence theory will never be proved, no matter how much new positive evidence is dug up by all those searches and examinations mentioned above? This question cannot be answered easily. We will end our discussion of this problem about scientific reasoning with the comment that not only is there much more to be learned about nature, but there are also unsolved problems about the nature of the science itself.

      Exercise \(\PageIndex{1}\)

      The explanation of the dinosaur extinctions most favored by today's scientific community is the one appealing to a violent impact or explosion. One of the reasons that this explanation is favored over reasonable alternative explanations is not that the others have been tested and shown to be inconsistent with the data but that the violence theory

      a. has not been falsified, unlike the alternative theories.
      b. has suggested a variety of new tests.
      c. is known not to be pseudoprecise.
      d. has been confirmed by deducing it from previously known facts and theories.

      Answer

      Answer (b). The violence theory not only is testable but can also be practically tested in many ways. The alternatives cannot be. Choice (a) makes the good point that the violence theory has not been falsified, but it makes the incorrect point that all the alternative theories have been.


    This page titled 15.5.2: Fruitful and Unfruitful Explanations is shared under a CC BY-NC-SA license and was authored, remixed, and/or curated by Bradley H. Dowden.

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