Overfitting the Bible (the Creation/Evolution Debate)

A few years ago I built a machine learning model to predict changes (up, down, or neutral) in Apple's stock price up to 3 hours in advance. When testing it against a past dataset, the model was correct 80% of the time. Cautiously optimistic that I would soon be a billionaire, I tested it with real-time data. The result: it was correct 50% of the time, no better than flipping a coin. So what went wrong?

My model was overfitting the data. Overfitting is when a model models noise (i.e., irrelevant data) rather than the signal (i.e., the true relationship between the input data and the output). Overfit models can superficially match the data very closely but usually don't make accurate predictions.

The above example of overfitting relates the maximum wind gust in Norman, Oklahoma to the number of points given up by the Oklahoma Sooners football team during 2013. The red curve fits the data points (red dots) very well but is not an accurate interpretation of them  (keep in mind that some of these games were played hundreds of miles away from Norman). Applying it to the 2014 Sugar Bowl gives a 20 point error. [Wind data courtesy of the Oklahoma Mesonet]

Overfitting is common in Bible-based theology. The Bible contains a lot of data, but the issues people debated 3000 years ago were not necessarily the same as those debated today. For example, Tuesday night I watched a debate between Bill Nye and Ken Ham. Ham used the Bible to argue against the theory of Evolution and for a 6,000 year age of the Earth. But was the book of Genesis written to teach biology and geology to scientists 3000 years later? Is the data relevant or was Mr. Ham overfitting it?

Ken Ham never presented an alternative to evolution because the Bible doesn't contain one. Genesis says God created animals and humans but doesn't explain how. It says the first human ultimately came from the soil, which sounds vaguely like evolution to me, but how soil became man is not explained. The entire process is covered in one sentence with no details. Even less is written about how animals were created. The author clearly wasn't trying to answer the same questions that evolution answers. Thus, using Genesis to deny evolution is overfitting the data. Likewise, using the vast evidence for evolution to deny the truthfulness of the Bible also is overfitting it.

The age of the Earth isn't mentioned in Genesis either. Ham infers it from genealogies and an assumption that the first human was created 5 days after the Earth was created. But does the Bible actually teach that?

Much of the argument is about the word "day". The Hebrew word "yom" usually is translated into English as "day", but it also is translated as age, period, time, lifetime, years, always, forever, eternity, and several other words. Hebrew has far fewer words than English, so they tend to have a broader meaning, very dependent on the context. So what does "yom" mean in the context of Genesis 1?

I think it probably means "day", but there's a catch. According to most sources, a "day" was understood by ancient near-eastern people as a cycle of lightness and darkness that the sun happened to follow. It was not, as we think of it now, an abstract measure of time equivalent to 24 hours or one rotation of Earth. Genesis 1 mentions three "days" that have "evening and morning", but before the sun was created on day 4. With the sun not yet existing, there's no reason to assume that a "day" had anything to do with the sun or that it was 24 hours long. There's also nothing to suggest that the meaning of "day" changes halfway through the chapter. I'm assuming here that Genesis is a literal description of creation. If it's anything else, there's even less reason to believe it's 24-hour days.

The Young Earth model closely fits a superficial, anachronistic, English reading of the text. In other words, it fits noise. The true test of a model is how well it makes predictions. Like my Apple stock price model and wind gust football model, the Young Earth model doesn't make accurate predictions. As Bill Nye pointed out, what we observe in nature is very different from what the Young Earth model would predict. But as with evolution, using evidence for an old earth as evidence against the Bible is to make the same mistake as Ken Ham.

Many Bible believers use the Bible to answer questions that the Bible doesn't actually address. Many non-believers find in the Bible absurd and immoral teachings that it doesn't actually teach. Both feel confident because their models fit the data, but both are overfitting it. Always remember that fitting the data is far different from accurately interpreting it.