EDITOR'S NOTE: This post is part of a series adapted from a scholarly essay titled "Miracles and Science: The Long Shadow of David Hume," first published in 2010.
Introduction: Miracles as violations of the laws of nature
“Unbelievable, isn’t it, that there are still students at this university who believe in stories from the Bible,” said Martin, an older colleague, at one of the formal dinners around which the traditional life of Oxford University revolves. “But Martin,” I answered, “their faith probably doesn’t differ much from mine.” I can still see his face go pale while he nearly choked on his glass of St. Emilion Grand Cru Classé: “How can you believe in such things nowadays – Walking on water, a resurrection from the dead? Those are miracles, and aren’t you a scientist?”
“Oh, how interesting,” say John and Ruth, a couple that I have just met at the end of a church service. “You are a scientist.” They look a bit unsure of what to say next and John blurts out, “I read recently that we still don’t understand how birds can fly so many miles to the south and yet return to exactly the same place each summer. Scientists can’t explain this; it is a miracle, don’t you think?”
I never quite know what to say next in such conversations. Perhaps nine years of living in Britain have made me too sensitive to that most cardinal of English social sins–causing embarrassment. But there is more to it than that. Behind these statements lies a tangle of complex intellectual issues related to the definition and scope of science, the nature of God’s action in the world, and the reliability and interpretation of the Bible. These have exercised many of greatest minds in history:
The debate between atheism and religious belief has gone on for centuries, and just about every aspect of it has been explored to the point where even philosophers seem bored with it. The outcome is stalemate.
So says my Oxford colleague Alister McGrath. Although these subtleties are well known to philosophers and historians of science, public discourse on science and religion often seems blissfully unaware of them.
Everyone brings a set of presuppositions to the table. To make progress, these should first be brought out into the open. Without time for an honest conversation in which we can listen to each other in depth, I won’t know exactly what Martin, John, or Ruth’s presuppositions are. But, for the sake of this essay, I will be a bit presumptuous and venture a guess. My guess would be that, although both seem to be on opposite sides of a vast divide, they are in fact influenced by a similar perspective on science and miracles, one first laid down by the great sceptical Scottish philosopher David Hume, who wrote:
A miracle is a violation of the laws of nature, and as a firm and unalterable experience has established these laws, the proof against a miracle, from the very nature of the fact, is as entire as any argument from experience can possibly be imagined.
This language of “miracles as violations of the laws of nature” has framed the debate ever since. Martin, John, and Ruth, perhaps without realizing it, are living under the long shadow of David Hume.
Martin may think that science is the only reliable route to gaining knowledge about the world, and that, since belief in miracles is obviously unscientific, such belief must ipso facto be false. John and Ruth may feel a similar tension between science and miracles, and are therefore encouraged by any natural process that seems inexplicable. Weakening the power of science would seem to strengthen the case for God acting in the world: If we know that today God miraculously steers a bird back to its original habitat after a long return flight to the south, then it is easier to believe that 2000 years ago he turned water into wine at a wedding in Cana.
Now, as a Christian scientist who believes in the miracles of the Bible, I take issue with both of the views above. But to explain this better, I need to first take a step back and answer two critical questions: What do I mean by science, and what does the Bible say about miracles?
The problem of deciding where to draw the lines around science has vexed generations of philosophers. Like many unsolved issues, it has been given its own name—“the demarcation problem.” Although one can determine with some degree of consensus what the extremes of the science/non-science continuum are, exactly where the boundary lies is fuzzy. This doesn’t mean, however, that we cannot recognize science when we see it, but rather that a watertight definition is difficult to create. The old fashioned idea (still taught in many schools) that scientific practice follows a well-defined linear process—first make an observation, then state a hypothesis, and then test that hypothesis—is certainly far too simple.
Science as a tapestry
Rather than attempt to come up with a careful and precise definition of science or scientific practice, I will instead resort to a favorite metaphor of mine. It originates with one of my former teachers at Cornell, the physicist David Mermin, who describes science as a “tapestry” woven together from many threads (experimental results, interpretations, explanations, etc.). It is only when one examines the tapestry as a whole that it will (or will not) make a convincing pattern.
Creating scientific tapestries is a collective endeavor building on mutual trust and the communal experience of what kinds of arguments and evidence are likely to stand the test of time. In part because the skill of weaving reliable scientific tapestries relies on subtle judgements, a young scientist may work for years as an apprentice of older and more experienced practitioners before branching out on his own. In this process there are many parallels with the guilds of old. I am fond of this metaphor because it describes what I think I experience from the inside as a scientist. Moreover, it also emphasizes the importance of coherence and consistency when I weave together arguments and data to make an “inference to a best explanation.”
The strong communal element inherent in scientific practice has at times been seized upon by sociologists of science to argue that scientific knowledge is just one more type of human construct with no greater claim on reality than any other form of knowledge. But scientists as a whole have reacted to this proposition in a negative way. Although they agree that all kinds of economic, historical and social factors do play a role in the formation of scientific theories, they would argue that, in the long run, the scientific process does lead to reliable knowledge about the world.
The view of nature embraced by most scientists that I know could be described as critical realism. They are realists because they believe that there is a world out there that is independent of our making. The adjective “critical” is added because they recognize that extracting knowledge about that world is not always straightforward. Thus, the primary role of the collective nature of the scientific process is to provide a network of error-correcting mechanisms that prevent us from fooling ourselves. The continual testing against nature refines and filters out competing scientific theories, leading to advances in the strength and reliability of our scientific knowledge tapestries.
Although there are many commonalities in the ways that scientists in distinct fields assemble their tapestry arguments, there can also be subtle differences. These differences are foisted on us in part by the types of problems that each field attempts to address. For example, as a theoretical physicist I’ve been trained in a tradition of what the Nobel Laureate Eugene Wigner called “the unreasonable effectiveness of mathematics:”
The miracle of the appropriateness of the language of mathematics for the formulation of the laws of physics is a wonderful gift which we neither understand nor deserve. We should be grateful for it and hope that it will remain valid in future research and that it will extend, for better or for worse, to our pleasure, even though perhaps also to our bafflement, to wide branches of learning.
We believe, based on a history of spectacular success, that mathematical consistency among threads is a key indicator of strong tapestries. These days, I spend much of my time interacting with biologists who tend to view my confidence in the ability of theoretical models to extract knowledge about the physical world with great suspicion. I, on the other hand, am often instinctively skeptical of the huge error bars that can afflict their data.
To a large degree, these cultural differences are forced on us by the kinds of questions we study. My reaction above arises because physics is self-limiting. As a community we simply don’t deal with problems of the same level of complexity that biology does. If an experiment is too messy we will often define it away by declaring “that isn’t physics,” and move on. Similarly, molecular biologists can afford to be more selective about their data than medical scientists or psychologists can.
But, despite these cultural differences, which can lead to heated and sometimes frustrating discussion, we do agree on a number of ground rules for defining what makes a tapestry strong. For example, what we either predict or measure should be repeatable. If I claim to see an effect in an experiment, someone else in a different lab should be able to reliably measure the same effect. That simple requirement has many ramifications for the types of problems we are able to address.
The Limits of ScienceThere are many questions that simply are not amenable to purely scientific analysis. A very lucid discussion of this issue can be found in the book The Limits of Science by Nobel Prize winner (and atheist) Sir Peter Medawar, who wrote:
“That there is indeed a limit upon science is made very likely by the existence of questions that science cannot answer and that no conceivable advance of science would empower it to answer… It is not to science, therefore but to metaphysics, imaginative literature or religion that we must turn for answers to questions having to do with first and last things.”
“Science is a great and glorious enterprise - the most successful, I argue, that human beings have ever engaged in. To reproach it for its inability to answer all the questions we should like to put to it is no more sensible than to reproach a railway locomotive for not flying or, in general, not performing any other operation for which it was not designed.”
Science’s great power derives from its self-imposed limits. It is wrong to ask it to pronounce on issues outside its jurisdiction. In fact, the most important decisions in life cannot be addressed solely by the scientific method, nor do people really live as if they can. In the words of Sir John Polkinghorne, former professor of Mathematical Physics at Cambridge and Anglican priest:
“We are entitled to require a consistency between what people write in their studies and the way in which they live their lives. I submit that no-one lives as if science were enough. Our account of the world must be rich enough – have a thick enough texture and a sufficiently generous rationality – to contain the total spectrum of human meeting with reality.”
But just because we don’t live life by the scientific method doesn’t mean that the only alternative is irrationality. For example, if I were to decide to get married, a truly irrational approach would be to pick a random woman off the street. Instead, assuming I find a potentially willing partner, it is wise to go through a period of courtship during which we get to know each other. We may also ask for the opinion of wise friends. There are helpful counseling programs with compatibility lists, etc. that, in fact, often use knowledge that scientific techniques have extracted from our collective experience and wisdom. But at the end of the day I can’t demand scientific certainty before deciding to marry someone. Nor is it wise to perform repeatable experiments! I need to make a volitional step because there are aspects of marriage that I can only see from the inside.
Another example of a method used to obtain knowledge is the legal process which, although it is a tightly organized system, is not strictly scientific. Similarly, a historian will use a combination of evidence (e.g. manuscripts) and understanding about the thinking patterns of a particular era to make informed judgements about what happened in the past. Clearly, this big question of how to extract reliable information about the world, how to separate fact from mere opinion, is indeed a very difficult and important one.