Wednesday, January 29, 2003

The philosophy of science, evolution, and Sacred Scripture

I've been reading up in the philosophy of science recently, and came across the notion of scientific theory (found first in Mill, but later in Hempel) that says that for any scientific theory, its explanatory content is the same as its predictive power. In other words, a scientific theory is a device for taking present facts and predicting future or undiscovered facts. Now, I have some problems with this theory about theories, since I think that theories are ways to get at metaphysical truths. But the caution is well taken: if the things we talk about in theories (force, atom, number) are not things that we sense, we must be careful in how we attribute existence to them. A decent test for the truth of a theory is whether or not it can predict future events.

As I read this last night, I thought about the theory of evolution. What sort of predictive power does this theory have? I can test the theory of gravity in a laboratory, and I can even test Einsteinian time dilation, if I have a good enough watch. But can I test evolution? Natural selection occurs over millions of years, so the theory says, and given enough time, amoebas can become elephants, or even more wondrous, human beings. But we don't live long enough to species changes, and therefore the theory of evolution has no predictive value. There are those who argue that species change does occur, but they say this only by making the definition of "species" so fluid that it has no meaning. If you consider dog breeding to be species change, then perhaps the theory works. But dog breeding is a far cry from developing human beings out of apes.

Evolution is an explanation that more or less fits the observed facts. But there are lots of theories that fit the observed facts, from six-day creationism to the Raelian cult's cloning theories. How do we decide among these theories? If none of them have predictive power, then how do we decide? We need to use unscientific criteria. I propose that we use a variation of Sherlock Holmes' dictum. Holmes said to eliminate the impossible, and whatever else is left, no matter how improbable, is the solution. I follow Dirk Gently (the famous detective invented by Douglas Adams), who says "Eliminate the improbable, and whatever is left, no matter how impossible, must be the solution." The reason for the change is that we don't know what's impossible, but we have an intuition about what is improbable. On Holmes' theory, God's providence is seen as impossible, and the improbable view that molecules can bounce into each other and make intelligence is believed. On Gently's view, bouncing molecules becoming intelligence is patently and absurdly improbable, and who knows if God is impossible? So perhaps we are able to affirm the theory of theistic evolution, as a simpler and less improbable theory.

How does this all relate to scripture? There are theories of biblical interpretation that purport to explain exactly how the text came to be. For example, there is redaction criticism, which seeks to determine how the text was edited together by some unknown editor, and source criticism, which looks for unknown sources. You may have heard of Q-source theory for the gospels. The idea is that the similarity in Matthew, Mark, and Luke can be accounted for by some unknown Q text, that no-one has ever found. Problem: is there any way to test this theory? Could we do a laboratory experiment, and subject a divine revelation to controlled variables and changed variables? Clearly not. So the historical-critical theories of biblical origins cannot ever be tested, and they have no predictive power, since revelation is closed with the death of the last apostle. All of these theories are and can only ever be a guess about what happened. No-one has ever found Q, and no-one has ever attempted to test whether this sort of criticism can lead to the truth. In fact, in the case of revelation, no one ever could test the theory, since revelation is a unique fact.

But, if you read the New American Bible (tm), you will find all sorts of footnotes putting forth as facts that which can only be a guess. For example, Matthew 22:1-14: "This parable is from Q. . . ." Not "this parable may be from Q, which no-one has ever found and is only a guess from scripture scholars," but rather "this is from Q." But there is no basis for using the word "is" in this case, since it is only a guess, and can only ever be a guess.

And that's why thinking about philosophy of science, theories, and evolution can cause me to recommend you never read the footnotes in the NAB.

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