On the supernatural

by Neil Rickert

There has been some recent speculative discussion on the blogosphere, as to the supernatural, and whether there could ever be evidence for it.  Since it is relevant to my posts on epistemology, I thought that I would add my two cents.

First some links.  Chris Schoen has posted Is “Dark Matter” Supernatural? Sean Carrol has further commented, with Is Dark Matter Supernatural? And now Jerry Coyne has commented on that, with Sean Carroll on the “supernatural”.

When considering possible effects of the supernatural, Sean Carrol lists three possibilities, which Jerry Coyne repeats:

  1. The silent: things that have absolutely no effect on anything that happens in the world.
  2. The hidden: things that affect the world only indirectly, without being immediately observable themselves.
  3. The lawless: things that affect the world in ways that are observable (directly or otherwise), but not subject to the regularities of natural law.

In the case of the first of these, there would be no evidence and thus no evidence of the supernatural.  In the case of the second, there would be evidence but it is evidence that science could investigate.  Thus it would not be considered evidence of the supernatural.  Incidentally, the dark matter mentioned in the links would fit with the second case.

It is only with the third case, direct violations of laws, that the authors see a possibility that there could be evidence of the supernatural.  I want to question that.

Suppose, as an example, a Newtonian scientist observed a case where an object was accelerating with no force applied.  Surely that would be a clear violation of Newton’s f = ma.  But that is not how the scientist would look at it.  Rather, he would use f = ma to compute a force, and would then assert that such a force must exist even if we failed to otherwise detect it.  The observed acceleration would be seen as sufficient evidence of the unexplained force.  So what at first looked like a clear violation of physical law, and hence a clear example of the third type of possible supernatural effect, would in fact be seen as an example of the second type of effect so would be considered to be something that science could investigate and something that is natural, not supernatural.

I picked just one example to illustrate the problem.  But I believe the problem to be quite general.  We could not find a violation of Ampere’s law, because the way we actually measure electrical current is based on Ampere’s law.  We could not find a violation of Ohm’s law, because the way that we measure electrical resistance depends on Ohm’s law.

There’s a common assumption that scientists form laws by first collecting data, and then observing patterns in the data.  But it is not nearly that simple.  The scientific laws are intimately connected to the ways that the data is defined and collected.  So easy contradictions are unlikely.

Some of this is summed up in the Quine-Duhem thesis.  Duhem observed, and Quine further discussed, that apparent problems for a scientific theory can be pushed elsewhere, to be a different kind of problem that we can live with while maintaining the theory.  Roughly speaking, we could take the Quine-Duhem thesis as saying that problems which at first appear to fit case 3 of Carrol’s list will in fact be instead understood as being examples of case 2 and will thus not be considered evidence of the supernatural.

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