In my first two posts of this series (PART 1 and PART 2), I laid a foundation with an epistemological account of the nature of explanations. Given that account, let us move to a more specific question: What constitutes a scientific explanation?
This is a difficult question because science notoriously resists definition. There is no accepted list of necessary and sufficient conditions that constitute an adequate definition of science. To demonstrate this problem, let us examine a highly popular feature often proposed as necessary and sufficient for an explanation to count as scientific. Many scientists and philosophers of science point to falsifiability as a feature that demarcates science from non-science. There are, however, a number of reasons that count against this criterion.
First, J.P. Moreland points out that “the nature of falsifiability in science is often difficult to clarify” (Christianity and the Nature of Science, p. 33). Science rarely tests propositions or theories in isolation. Any number of theories may be in play during experimentation. But what if the scientist’s observation does not correspond with his predictions? Which theory in play has been falsified? Has the entire cluster of theories been falsified?
There is a second problem with falsification. In our account of explanation, we made a distinction between meta- and minor-explanations, a distinction clearly evident in science. I may hold to some evolutionary meta-explanation regarding the origin and existence of biological life, but at the same time hold to minor-explanations (e.g. that a particular feature of a certain bacteria confers upon the organism some survival advantage) that may fall under umbrella meta-explanation. While the minor-explanations may be easier to falsify, broad meta-explanations are very difficult to falsify as they may encompass entire clusters of minor-explanations. Certainly, falsifiability is relevant to scientific explanations but it cannot constitute a necessary or sufficient condition.
What then are we to do? How do we differentiate between mere explanation and scientific explanation? We may find some progress in identifying a cluster of features that would make an explanation scientific rather than historical or sociological, et al. However, we recognize that taken individually or collectively they would not constitute necessary or sufficient conditions.
First, scientific explanations should exhibit correct deductive or inductive argumentation. The explanadum should be explained by inferring it from the explanans.
Second, scientific explanations should be empirically accurate. Observation, prediction, and experimentation are foundational to scientific inquiry. Positive empirical testing leads to important observations. Important observations lead to law-like generalizations. And continuing scientific testing provides important justification or disconfirmation of scientific explanations. Thus, scientific explanations should cohere with available empirical evidence (anomalies not withstanding).
Third, scientific explanations should include generalizations about laws. Over time, certain scientific predictions are confirmed through observation or experimentation. Given enough justification, they can be taken to demonstrate certain patterns of regularity within the world. From such regularities, scientists can deduce law-like generalizations that are causally responsible for those regularities. And those laws can guide further fruitful scientific investigation.
I have given an account of explanation that is narrow enough to be useful, yet broad enough to be adequate for all disciplines. Although we cannot list necessary and sufficient conditions for what counts as scientific explanation, we can outline a cluster of features that help in this task. We are now in a good position to consider the nature of interaction between science and theology and to follow evidence from both disciplines wherever it may lead us.