Let's talk a moment about the theory of Plate Tectonics.
Scientists have this new-fangled theory about the continents sitting on huge "plates" that slosh around all over the place and collide with one another. They even say that at one point, all the continents were all joined up together in one big piece! They say they have a lot of evidence, and let's be honest, we're not arguing that there are certain facts we can agree upon, it's simply the interpreation of these facts that we disagree with. I mean, we've all experienced earthquakes or tremors, and this kind of micromovement we can agree upon, but macromovement? The movement of entire continents? I think not! Were you there to see them move? Also, isn't the whole thing rather circular? Earthquakes occur along fault lines and we know where fault lines are because earthquakes happen there? I'm not saying we shouldn't teach plate tectonics in geography and geology classes, merely that we should teach the strengths and weaknesses of the theory, teach the controversy, and let the kids decide. After all, it is only a theory.
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Of course the above paragraph is mostly bullshit. Plate tectonics is indeed an accepted science, and there is a lot of evidence for it (some quite recent). The point is, the exact same argument made by creationists against evolution can in fact be used against every area of science, and this is what some of them are actually driving at. Part of the problem, for some of these people, is that science doesn't deal in proof. It deals in evidence and the most likely explanations for a series of facts.
So, to begin with, let's get a few things straight.
A fact, in science, is roughly equivalent with the idea of data (though humanity studies love to point out that data is what is "given" while a fact is "made"...thanks guys). It is an observation that can be objectively verified. For example, it is a fact that when I release an object, it falls down. It is a fact that the sun appears to rise in the east. It is a fact that earthquakes occur. It is a fact that the magnetic orientation of rocks on various continents align to a point in space as they are now, but if the continents were closer together, they would converge on the north pole. It is a fact that we have a large, though certainly incomplete, fossil record of species that seems to show transformations from one to another while preserving significant morphological, geographical, biomolecular (in some special cases), and chronological similarities. It is a fact that we have witnessed events of speciation the lab and in the wild within the past few decades. It is a fact that we have witnessed novel mutations bringing about a net increase in fitness. Several of my previous posts deal with these issues and more.
A law, in science, is a description of how certain principles operate, typically expressed in mathematics. For example, there are Newton's Laws of motion. These describe the ways that objects behave and finally pin down those really hard observations like "the harder you shove something the faster it moves." I'm not trivializing here - F=ma is a very important law, and it took us centuries to nail it down. Good going, Newton. Likewise, there is Newton's Law of Gravity - it describes to a fair degree of accuracy how two bodies of mass interact with one another in the absence of other forces. There are also laws in population genetics, a field with some notable influence in evolutionary biology. A law is not the "highest" class of scientific ideas - they are merely a subset of them. Getting a law named after you is a pretty cool thing, though.
A theory, in science, is a well-tested explanation that attempts to tie together a large set of facts and laws and explain why they are the way they are. For example, we had Newton's Law of Gravity for a long time (as well as his theory), but it failed in some important aspects, specifically with the orbit of Mercury. Also, his theory had low plausibility. It wasn't until Einstein that we understood why the planets orbit the way they do (i.e., due to the curvature of space-time), and also picked up some pretty cool new predictions, such as gravitational lensing. These predictions, a necessary component of any theory, allow for evidence supporting its veracity, but they don't "prove" a theory true. A theory never graduates into a "law" or any such thing, it either stands the test of time, or is falsified and rejected in the harsh reality of the scientific world. What works stays and gets refined over the years, what doesn't work is rejected and scorned. Sorry, them's the breaks. So, for example, we still don't say that Einstein's Theory of Relativity has been proven true - people are constantly trying to disprove it. However, so far, no one has been able to offer verifiable evidence against it. It stands thus far, but may be replaced in the future. That's one of the wonderful things about science, we go where the evidence leads us, and we're willing to change our minds. Hell, we may even win a Nobel Prize in the process. Sweet! This is also why the "just a theory" claim is so laughable. A theory is a battle-tested and hardened contentor in science. We want to teach our theories, they're the best explanations we have in the world.
Anyways, back to what this has to do with plate tectonics and evolution.
I've heard the arguments I started out with said about evolution all the time. It's really pretty trite, I must say, and five minutes with a google search or a good librarian should be able to clear up these misconcepts. Darwin proposed his theory of evolution in 1859, and within a few decades, the scientific debate over the matter was settled - Darwin was right. Now, the funny thing is, I hear people say all the time, "We have evidence for microevolution, but not macro. That's just fantasy." What makes this laughable, beyond its merely being invented by creationists, is that it comes from our rather peculiar time in history. Had we lived when Darwin first published his book, the argument would have been exactly the opposite. Darwin based his theory on evidence from palentology, biogeography, comparative anatomy, physiology, and embryology and drew a very large picture. He had no workable theory of inheritance, the "micro" of this particular scale. It wasn't until the 1950s, actually, until we had a solid model of that, which allowed for the neo-Darwinian synthesis. Since that point, Creationists have been making a huge effort to ignore or create elaborate explanations for all the evidence that had existed and continues to mount against them.
One of the more laughable comments from creationists is the "Where you there?!" question, intended to cast doubt on any scientific theory, because, as they say, it is supposed to be based entirely on "observable evidence," which for them means only which can be seen under a microscope in a lab. I'm sorry, creationists, but science is bigger and more imaginative than that. When you have a theory that allows for predictions, and can go out and test those predictions, and follow the evidence, well, that's science. For example, Neil Shubin knew that there had to have existed an intermediary between fish and amphibians. He predicted, based on the theory of evolution, when this type of creature had to have lived. He went out and found rock of that age (I may go into how geological layers are laid down, and why there is no single geological column that contains all the layers, in another post), and bam...there Tiktaalik was. More confirmation of the predictions of evolutionary theory, which goes to offer more support for evolutionary theory. Listen, if you want to say evolutionary theory is false, well, okay, you've still got to explain the facts of evolution that we've seen, as well as come up with evidence that the theory doesn't work, and supply a theory that has at least as much evidence and plausibility as evolution has going for it now.
Now, the plausibility bit is important. The old saw is "extraordinary claims require extraordinary evidence," and that's true. The more prior plausibility you have, the less extraordinary the evidence you must have to make a claim believable. For example, if I am known to love cookies and tell you that I had a cookie this afternoon, you'd probably believe me. If, however, I am deathly allergic to cookies, have shown you how terrible my reactions are in the past, and then saunter in and tell you that I just got done eating twenty-three pounds of cookies, you'd probably ask for some proof or just assume I'm bullshitting you. It's the same in science - the work is still based on evidence, but the more out-there your claims, or the more it directly contradicts all the evidence we have so far, or proposes new mechanisms, the more evidence you have to have to convince people. Likewise, this is why supernatural explanations don't work - they have low prior plausibility and they are utterly untestable. Science is a field in which testing is supreme. When you say you want to insert an untestable, unnatural explanation in there, you've got a contradiction of terms.
Some people say that evolution is a circular argument - the survival of the fittest really means that whatever survives is the fittest. Well, not really. Evolution predicts the differential survival of individuals dependent on the interaction of their differential genetic and behavioral characteristics and the dynamic environment. "Fit" is not a static thing, it changes from environment to environment and from species to species. Sometimes, otherwise fit organisms die in catacylsmic events. Too bad. What you end up with the differential survival of alleles in populations. That's the important thing - evolution is about populations.
Evolutionary theory takes evidence from biology, palentology, geography, geology, chemistry, and many other fields to create a comprehensive explanation for the diversity of life forms and generate new predictions. There are significant controversies in evolutionary theory, but they're not the ones that creationists tell you about. They're about things like gradualism versus punctuated equilibrium and the overall influence of genetic drift versus natural or sexual selection. If you doubt evolution, with all the evidence for it, I would argue either you haven't done your homework well enough, have been indoctrinated against it, or should also doubt that gravity exists, that the earth is roughly spherical, that modern medicine has anything going for (as so much of it is based on evolutionary theory anyway), or that atoms exist. We're talking about the same levels of evidence here.
Anyways, look up plate tectonics sometime. It's a fascinating field, and some of the lines of evidence for it are just great. Science, people!
Lastly, a guy I've had some frequent debates with, Tom Sheepandgoats, is fond of a phrase: "Why should I listen to scientists telling me that my car doesn't work when I'm driving along in it?" It's pithy, I admit. I can understand the feeling behind it - some of science is quite counterintuitive and some of it is incredibily difficult to grasp. However, my response would be that it was in fact science and technology that built the car and explain how it works in the first place - how chemical reactions release energy stored in hydrogen bonds in the hydrocarbon fuel and powers a drive train to produce rotation in the wheels, which interacts through friction with the road to propel the car foward. In fact, it seems more the creationists who want to argue that the car can't work, even though it clearly does. They continually deny evidence put before them, or argue things along the lines that because the drive train can't steer the car or because the steering wheel can't propel the car, cars are impossible, or because they haven't personally seen any tractor trailers, they deny the possibility that tractor trailers exist, even though other people have seen them.
For one example of this, I'm going to go for radioisotope dating. You get a lot of claims about radiocarbon dating being wildly inaccurate or incorrect. For example, Kent Hovind loves to talk about living mollusks being dated to millions of years old, or shrimp, or marine seals....hmm...there's something going on here. His statements are actually true - these creatures have been dated with obviously wrong dates, but they are also incredibly misleading. In one video, Hovind even cites one of the studies he's quoting from, but he doesn't give the title - which clearly states that the paper is about fraudulent dates for mollusks and marine animals and why it happens. Listen, these creatures are filter feeders that tend to live in and feed on carbon-14 depleted environments. This becomes incorporated in their shells and bodies, and then when other marine predators eat them, they likewise absorb depleted carbon. It's true, radiocarbon dating is very inaccurate for marine organisms, and this is one of the reasons that scientists don't use it for those types of creatures! See, that's the other thing. Scientists aren't stupid. They know the limits of their tools and they're careful to describe exactly what they're doing with what and why. You use radiocarbon dating for a narrow range of materials and it has a limited time period in which it is generally accurate. Luckily, we have many other kinds of radioactive dating, all of which can be independently verified by other means. Likewise, creationists often play up the "random chance" element of evolution - the mutations. They always forget the selective elements, or the evidence that mutations can increase fitness. If you need a real-world, real-time example...let's use viruses, Influenza A H1N1, for example. There you go. Thank you, done.
That's about it for now. If you want to comment or debate any of these issues, feel free to reply. Likewise, if you see any mistakes, go for it.
Friday, May 8, 2009
Let's talk a moment about the theory of Plate Tectonics.