Observational vs historical science

Update: For another take on this, check out this great article by John Timmer.

In last night’s debate between Bill Nye and Kentucky’s Creation Museum founder Ken Ham, Ham focused on a favorite argument of his. Ham thinks all of science can be neatly divided into two types: observational (or experimental) science, and historical science. In his view, observational science is sound, because it can be tested in a laboratory. Historical science, however, is just a belief about the past that cannot be tested, and so is not really science. Now that’s an atrocious misrepresentation of the way that, say, geology, is actually done, but it’s a tremendously useful claim for Young Earth Creationists like Ham.

It allows them to shrug off virtually any piece of scientific evidence that disagrees with their religious contentions about the history of the Universe and life on planet Earth. The first bit is obvious. By positioning any science that deals with the past as merely conjecture, they need not deal with evidence at all. “Well, you have your beliefs and I have mine,” they can say. Suddenly, the accumulated knowledge of centuries of scientists has been put on equal footing with a literal and dogmatic reading of the Bible. The second bit is even more pernicious. If evidence of physical or biological processes in the modern day (fitting under Ham’s umbrella of “observational”, and therefore trustworthy, science) causes problems for the Young Earth Creationist viewpoint, it is simply claimed that the observed process must have been different in the past– which, of course, is not a claim that can be tested with evidence because it is “historical”. During the debate, Ham stated that treating physical processes as if they functioned similarly in the past is just an assumption. (His contention that the very laws of physics twiddled around capriciously in just the right way to make each of his outrageous claims work out, however? An acceptable assumption, to him.) In this way, every scientific weapon that could possibly do damage to the claims of Young Earth Creationists is blunted and turned away.

Let’s put the past behind us

But how is this so-called “historical science” really done? Are we merely forming beliefs about the past that cannot be tested? The answer is an emphatic, resounding, “NO!!” In the debate, Bill Nye used an example that many in the audience could relate to: the TV show CSI. We all have an intuitive feel for the fact that forensic evidence at a crime scene can tell us about who was there and what happened. Let me try a simpler analogy.

Imagine that we’re examining ancient tablets on which Arabic numerals (1, 2, 3…) were once drawn with pricks of black pigment akin to a tattoo. As the tablet has been worn, chipped, and even broken over time, many of the dark points are gone. How, then, can we determine which numeral was drawn? Well, whether or not you realize it, we have 10 working hypotheses for each digit. That is, it could be 0-9. Each numeral has its unique shape. Now, we carefully map the position of the remaining points and see this.


We can rule out some of our hypotheses– some numerals. The numeral 3, for example, is not consistent with these points.


That was a test. The data points, these literal points of pigment, eliminate some of the hypotheses. Which hypotheses remain? Well, it could be a 1, obviously. It could also be part of a 4, or even a 7 drawn straight up and down, or possibly even a 9 without a curve at the bottom. However, that means there are 6 numerals we know it cannot be. Now, perhaps we study enough of the numerals in this archaeological find to learn that 7s were always drawn diagonally and 9s with curves. And let’s go a step further, and say that the iron in the pigment suffused into the surrounding material such than an MRI can show us if a point was once near a surface that has since eroded. That MRI shows no signs of the rest of a numeral 4.

Now, we will have our caveats and perhaps, in this silly example, we will not be 100% confident in our conclusion, but we will be able to say that the available evidence is only consistent (or at least most consistent) with a numeral 1. Because we are thinking scientifically, we will always be open to future evidence challenging this conclusion. If a new kind of analysis somehow finds points tracing out the rest of a 4, we will immediately revise our conclusion to state that the available evidence is most consistent with a numeral 4. Were we there to see the numeral drawn? No. Do we have a complete copy of it? No. Is our conclusion merely an assumption untested by evidence? Absolutely not.

Ken Ham misrepresents the scientific study of Earth or cosmic history because he has to in order to defend his beliefs, which are completely inconsistent with the available evidence.

Elementary, my dear Watson

In science, we must always be careful to make a distinction between an observation and an interpretation. Observations are inarguable. They are measurements. A telescope measured a given intensity of light at x wavelength. A mass spectrometer measured a given ratio of isotope A to isotope B in a mineral sample. Interpretations provide meaning to observations. According to this calculation, that isotope ratio corresponds to an age of x.x million years. If research causes some detail of that equation to change slightly, our calculated age will, too. That wouldn’t, however, change the measured isotope ratio.

When thinking scientifically, observations must always be in control of interpretations. Or as Jacob Bronowski put it, “This is the scientist’s moral: that there is no distinction between ends and means.” Your conclusion is only good to the extent that you carefully followed the scientific method.

For Ken Ham and other Young Earth Creationists, however, things are much different. As Ham freely admitted several times during his debate with Bill Nye, his starting point is that his literal reading of the Bible is an unerringly accurate representation of the world. He starts with an interpretation about the world– that a global flood ravaged the Earth and must account for the details of life history and the Earth’s surface, for example– and constructs a force-field of Biblical inerrancy around it. Any observation that is inconsistent with the interpretation is explicitly rejected. It bounces right off. Observations don’t tell Ken Ham that his interpretation is wrong. Ken Ham’s interpretation tells him that the observations are wrong.

So, in fact, even the “observational science” that Ken Ham lauds as trustworthy is antithetical to the thing he calls “creation science”.