Tuesday, March 22, 2011

The Possibility of Historical Evidence for Miracles (Part 2)

This post is part of my series on miracles. For an index, see here.

I’m currently looking at the following article from Morgan Luck:

In this article, Luck assesses Richard Swinburne’s argument for the viability of strong historical evidence for miracles. As noted last time, Swinburne’s argument is based on three key assertions. We have already considered the first of these assertions, in this entry we’ll consider the second:

  • Assertion 2: The existence of particular present events could be indicative of the prior occurrence of particular violations of the laws of nature (thanks to event causality).

With this assertion, Swinburne is distinguishing himself from those who think that the chief or sole evidence for a miracle is the testimony of eyewitnesses. He is claiming that we could have hard, physical evidence for the prior occurrence of miracle.

1. Jones goes down to the river
The general principle upon which Swinburne’s argument rests is the following:

  • If event E consists in a state of X being followed by a state Y, and we have a trace of state X and an observed later state Y, then we have some evidence that E occurred.

To illustrate the principle, Swinburne asks us to imagine the following story of a man named Jones and his remarkable river-crossing adventure. The story begins with us observing Jones’s footprints in soft mud on one side of the river and Jones himself on the other side. We know for a fact that footprints in this soft mud could not have been left more than a minute ago. We also observe that Jones’s clothes and body are dry and that there are no bridges, boats, aeroplanes or ropes nearby which he could have used to get across.

Under these circumstances, Swinburne argues that we are justified in inferring that a miracle of some kind has occurred. Specifically, that Jones has walked on water. The argument rests on a simple inference that makes use of the principle outlined above:

  • Jones's walking on water would be followed by a dry Jones being on one side of the river and his footprints being on the other side, provided no other means of transportation was available.
  • We have evidence of a dry Jones on one side of river, & his footprints on the other side, with no other means of transportation apparently available.
  • Therefore, Jones must have walked on water.

2. The Principle of Causal Closure
Luck thinks there are serious logical problems with Swinburne’s argument. This is because the possibility of a violation-miracle undermines the indicative strength of historical evidence.

To see why this is the case, we must first appeal to something known as the principle of causal closure (PCC). The PCC is a commonplace is debates over free will and determinism. It maintains that every event is causally determined by a combination of physical laws and the prior physical states of the universe.

The great advantage, from an explanatory point of view, of the PCC is that it means one need only cite natural causes to explain natural effects. The problem for Swinburne is that miracles would violate the PCC because they involve a supernatural agent disrupting the ordinary course of events. This creates problems for the kinds of inferences we can make from present day evidence to events in the past.

3. Using the Principle of Causal Closure
These problems become readily apparent when we consider how we make use of the PCC in our everyday lives. You are making use of the principle right now. As you read this, you are assuming that there is computer screen in front of you upon which some text is displayed. You assume this because you know that, in the ordinary course of events, light is being reflected from the computer screen, is travelling into your eye and on into your brain where the perception of the screen is created.

All of these assumptions rely on the PCC because they assume that one physical event determines another physical event. If the PCC is violated, then these assumptions go out the window. We have to accept other possible explanations of our experiences. For example, you would have accept that there is a possibility that there is no computer screen in front of you and that your experience is an illusion created by God.

Applying this to the case of Jones and the river we note that, without causal closure, it is:
“...quite possible that Jones could have swum across the river and god afterwards caused him to be dry, or god may have spontaneous[ly] created fresh footprints on one side of the river and Jones may never have crossed, alternatively God could have directly created the sensation that we are observing a dry Jones and he is in fact soaking wet after having swum across the river.” (Luck 2005, 16)
Other scenarios are possible as well.

The violation of the PCC thus creates a problem for the proponent of historical evidence for miracles. Luck is at pains to point out that the problem is a relatively modest one. He is not claiming that there can never be evidence for the occurrence of miracles. He is simply claiming that the evidence could be consistent with any number of potential miracles.

Despite its modesty, I think Luck’s point is important. Miracles are often deemed to be theologically significant because of the particular form they take. For example, the resurrection is thought to have particular theological significance for God’s plan of salvation. If it turns out that the evidence for the resurrection is consistent with a large number of potential miracles, then these theological interpretations of the resurrection fall by the wayside.

That’s it for this post. Next time out, we’ll consider Luck’s evaluation of Swinburne’s third and final assertion.


  1. Is that seriously Swinburnes argument? I don't see how it could possibly be defended. It's more likely that a couple birds landed and happened to make footprints shaped like a humans or that someone else other than Jones made the footprints and then retraced their steps or that Jones used a boat and released it downstream after he crossed. That's just off the top of my head, I'm sure there are plenty more potential explanations that are much more likely than someone walking on water.

  2. That's Swinburne's argument as presented in Luck's article. I'm not sure exactly what Swinburne originally said but Luck does give a fairly sizeable quote from him.

  3. This is an interesting point -- the more one buys into a miracle as a deviation from how things work... the more one would seem to concede that induction isn't all it's cracked up to be. So then why assume anything not understood wasn't a miracle (though, I suppose this is the reason for theologists creating criteria for miracles...)? If natural laws and typical causal chains apparently need not be followed, why assume that they do?

    Thanks for breaking things down so "bite sized." When I have a free evening (like tonight), your little snippets make for delightful reading and thought stimulation!

  4. Wow -- while I was writing "theologist" I recall thinking that didn't sound right. Then as I'm summarizing this to my wife and say theologian without even thinking, I had that feeling like I'd made a fool of myself in the above post :)

  5. Actually, I've seen "theologist" in a number of sources (including the dictionary). I don't think it's wrong, although "theologian" is certainly the norm.