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.
Hi Brett - this is a great series, lots of food for thought as to how Christian Theism integrates with science. Christians who are also professional scientists (like me, PhD physicist) are keenly interested in the integration of science and Christian Theism (see www.asa3.org, for example).
Your third point seems to me to have the relationship between the regularities and the generalizations reversed, this sentence in particular:
From such regularities, scientists can deduce law-like generalizations that are causally responsible for those regularities.
I'd like to offer an alternative statement of the point you are trying to make:
Let me define two concepts:
1. The Laws of Nature(the physical universe, designed and created by God): these are the properties and dynamics of the 'stuff' that the physical universe is made of. The regularities and patterns that we observe are due to these laws. From a Christian point of view, these are the Laws Of God's Physics - how Nature works as God understands it, and sustains it.
2. The Laws of Physics: these are our generalizations and mathematical frameworks that we have constructed to describe those regularities and patterns that have been designed and implemented in Nature and are inherent to Nature (by God Himself). Our generalizations are not causally responsible for Nature's dynamics - it is the other way around. Now, I am a critical realist and hold to a correspondence theory of truth, so I think our Laws of Physics are (hopefully, increasingly) good approximate descriptions of Nature (or perhaps even God's Physics), as we observe and experiment with various systems at ever increasing resolutions. The fact that we can apply our knowledge to construct technology that actually works suggests that we are on the right track.
What do you think?
Posted by: Victoria | December 17, 2014 at 07:42 AM
Victoria, in most of the things I've read, "Law of nature" and "laws of physics" are used interchangeably. Are these technical definitions you're using, or is this the way these terms are generally used by physicists, or is this just how you prefer to use these phrases?
Posted by: Sam Harper | December 17, 2014 at 08:53 AM
@Sam
I'm using the distinction to disambiguate between how Nature actually behaves (God's physics), and our descriptions and mathematical models of that behaviour (humankind's physics). I think that there can be a real correspondence between the two, and that we really can see what principles God used to design Nature - my current favourite is the universal applicability of the Principle of Least Action (or Stationary Action) - the fact that the dynamics of a system can be described by the time integral of a Lagrangian function, and requiring that this integral be stationary (first derivative = 0) to extract the dynamical equations (see the Euler-Lagrange equations) for the system. This carries with it a whole lot of implications: (see Noether's Theorems) related to symmetry and conservation laws; originally developed as a deeper understanding of Newton's 3 laws, it can be extended to electromagnetism, quantum theory, special and general relativity very naturally. This principle has to be postulated as axiomatic - there is as yet no more fundamental theory as to why this applies to Nature.
Ever wonder why gravity behaves as a spherically symmetric inverse-square-law force? Because we live in a universe where the macroscopic geometry of space-time is (3 space, 1 time) dimensional. But that only follows because Gauss' Divergence Theorem holds for any N-dimensional space, and the gravitational force is irrotational (zero curl - see Helmholtz's Theorem: a vector field can be completely specified if its divergence and curl are known).
Yet Newtonian gravity is only approximately correct - it works well enough in the appropriate scale limits, but we need General Relativity to understand what we can observe at higher resolutions.
Posted by: Victoria | December 17, 2014 at 09:33 AM
Victoria,
I understand the distinction you're making. What I'm wanting to know is whether this distinction you codify with the phrases "laws of nature" and "laws of physics" is codified by those same phrases by all physicists or not. Are you just choosing to use these phrases this way, or are these technical definitions that all physicists would use?
Posted by: Sam Harper | December 17, 2014 at 10:29 AM
I also think that the answer to Eugene Wigner's essay on the "Unreasonable Effectiveness of Mathematics in the Physical Sciences", is that God thought of it first, and designed His Laws of Physics accordingly, so that we could have the joy and privilege of discovering it for ourselves.
Posted by: Victoria | December 17, 2014 at 10:29 AM
@Sam
I can't speak for all physicists, but most of the Christian physicists I know would subscribe to that distinction. I'm sure if you went to the American Scientific Affiliation web site, you'd find articles discussing this very topic.
The reason and necessity for the distinction should be obvious - our 'laws of physics' are always subject to modifications and corrections, as our insight and ability to resolve details more precisely improves.
For almost three centuries, Classical Physics were 'The Laws of Physics = The Laws of Nature', until Relativity and Quantum Physics changed all that. Currently, Quantum Field Theory and General Relativity are our two fundamental frameworks, yet they are incompatible. From cosmology, we understand that there would have been a time when the entire universe (all of spacetime itself) was at a size where quantum effects would be important. Yet, we have no good theories for unifying QFT and GR yet (maybe M-Theory (or string theory), maybe Loop Quantum Gravity, maybe ???). Yet this is no problem for Nature or God - He has always known what the real physics is.
Even in QFT, all the really interesting calculations are perturbation series (see for example, 'determination of the fine structure constant from magnetic moment measurements'), and the mechanisms by which a field creates and annihilates its particles are opaque to us - the formalism describes what is going on in those terms, but doesn't let us see behind the veil.
Posted by: Victoria | December 17, 2014 at 10:49 AM