I don’t spend much time these days reading about the colourful and exotic habits of that other hominid species, homo creationist. It’s not that I’m not interested in the alien mythologies of strange creatures. It’s just that the subject is very old news. Much more than 6,000 years old, in fact.
But every so often I’m drawn to the weird world of these alien beings, and when I am, I’m reminded all over again that the big difference between our two species is not what we believe but rather how we believe.
Whatever your earliest exposure to philosophy, logic, and the scientific method might have been, it’s pretty certain that one of the first topics covered was the distinction between deduction and induction, followed closely by an introduction to the notions of a priori and a posteriori principles.
Well aware that I risk being pedantic and patronizing – more or less the same thing, really – let’s take a look at these terms before moving on to some real life examples, as outlined in an article titled “Tracking Creation in Glen Rose,” published by the Texas Observer on April 9th.
(If you’d rather skip my rehash of Logic 101, head on down to the middle of this piece, to the paragraph that starts “When people reason this way … .” I’ll never know that you didn’t read the whole thing.)
Deductive reasoning describes a logical process in which, if the premises (assumptions) are true, the conclusion must also be true. This is due to an appropriate construction of the argument, as in “Fido is a dog,” “All dogs are mammals,” “Therefore, Fido is a mammal.” Simple. All members of the dog category are mammals, and Fido is a member of the dog category. Ergo, a valid argument.
A truth problem arises, however, even in valid arguments, if the premises (the assumptions) are not themselves true. For example, “Fido is a dog,” “All dogs are invertebrates,” “Therefore, Fido is an invertebrate.” The argument is still valid, for if all dogs were in fact invertebrates, Fido, who is a dog, would be an invertebrate.
But of course Fido is not an invertebrate. What happened? The argument is valid (it’s form is correct), but it’s not sound. That is, it’s not true. Why not? Because one of the premises is not true. True plus true equals true in a valid argument, but true plus false equals false.
Try this one. “The universe is 6,000 years old, give or take a decade,” “There are dinosaur footprints in Glen Rose, Texas,” “Therefore, the Glen Rose footprints are no more than 6,000 years old.” This kind of reasoning leads to creation theme parks, where little cave children play with their pet baby pliosaurs.
But according to all of the evidence, the universe is not only 6,000 years old. What to do? Well, you could say to yourself, “Oops, I got that one wrong.” Or you could do what creationists do, which is to reframe the argument.
“God made the universe 6,000 years ago,” “The dinosaur footprints at Glen Rose appear to be more than 6,000 years old,” “Therefore, the science is wrong.” But that doesn’t work, because there’s absolutely no evidence that the science is wrong. OK, then, try this one. “Therefore, God faked the evidence.” (Presumably, to test our faith by leading scientists astray.) Or, a bit more sophisticated, “Therefore, God played with time.”
OK, these are pretty silly arguments – unless you subscribe to the conceptual assertions (a kind of a priori reasoning) that God exists, that he created the universe, and that the Bible that tells us that he did this about 6,000 years ago is infallible.
Start with these assumptions, and what happens to contradictory evidence? Well, to start with, it can’t be true, because we’ve already accepted the conceptual context above. So any contrary “evidence” must be either wrong or faked (by God or by evil scientists).
Take a silly but simple example. “Fido is a dog,” “All dogs are invertebrates,” “But Fido is not an invertebrate.” What are our options? We can alter any one of our statements. We can assert that Fido is not a dog because he isn’t an invertebrate. We can assert that, in fact, looking at the evidence, dogs are not invertebrates. Or we can assert that, despite the appearances, Fido is, in fact, an invertebrate.
The same reasoning process could apply to the Glen Rose footprints – except that we are constrained by our a priori assumptions. We can’t do anything but deny that the footprints are more than 6,000 years old without abandoning our core conceptualizations. Therefore, the footprints aren’t more than 6,000 years old. Problem solved.
When people reason this way, they usually fail to see anything wrong. Crucially, they fail to see that the problem is that they’re arguing from unproved assumptions. When you do that, you can’t assert the truth of your conclusion, no matter what you believe. What you end up with is “God exists (???),” “God created the universe (???),” “The Bible that tells us that he did this about 6,000 years ago is infallible (???),” “Therefore, the dinosaur footprints at Glen Rose are either younger than 6,000 years old or they’re fakes (?????????).”
This is not a good spot in which to find yourself. After all, there is the sound reasoning principle that “He who asserts must prove” – the Burden of Proof.
And worse, many of the people who reason this way believe that this kind of “I believe it, therefore it’s true” is just as valid and just as meaningful as the quite different kind of reasoning used by science: inductive reasoning and a posteriori postulations.
Inductive reasoning doesn’t produce the kind of unyielding certainty that deductive arguments do. Inductive reasoning argues from the particulars to the general, precisely the reverse of the way that deductive reasoning works. “I’ve seen many dogs, and all of them have been vertebrates,” “Fido is a dog,” “Therefore, Fido is a vertebrate.” Not 100% proved, but entirely un-disproved, which, according to Karl Popper, is as good a kind of probability as we’re ever going to get.
(You may have noticed that I’m ignoring all of the invalid arguments, such as concluding in the paragraph above, that “Therefore, all invertebrates are dogs.” This article is getting long enough as it is!)
Inductive reasoning requires evidence. That’s how it works. No evidence, no premises. No premises, no conclusion. It’s just that easy.
It’s impossible to prove a deductive conclusion based on conceptual assumptions like “God exists” or “The Bible is infallible.” In a real way, there is no factual assertion with which to engage. That’s why we have a Burden of Proof. Without it, any opinion about anything would be just as reasonable as any other opinion about anything else.
In fact, that’s exactly what some of the Glen Rose creationists – remember the Glen Rose creationists? This is an article about the Glen Rose creationists – believe.
“I believe in the Bible,” McFall says. “I don’t believe the world’s over 6,000 or 7,000 years old. Course, everybody’s got their own interpretation.”
Well, no, that’s not good enough. You’ve got your belief despite the evidence because you’ve framed the argument with a set of a priori assumptions that do not depend on evidence. Some other people, like scientists, express their conclusions with an a posteriori assertion that depends entirely on the evidence.
“Most everyone in Glen Rose that I know believes man and dinosaurs coexisted,” Alice Lance tells me at the annual tractor pull. “The only conflict we have is when people move from metropolitan areas and have different value systems. I think some don’t have a strong [religious] belief system, and they’re more likely to go with science than faith.”
“More likely to go with science than faith” is not the same as “More a Sooners fan than a Longhorns fan.” Ms. Lance thinks that she’s being kindly and understanding in pointing out that those poor folks from “metropolitan areas” just lack the requisite belief system. What she’s doing, instead, is showing that she doesn’t understand the category difference between arguing from presumption and extrapolating from evidence. Her belief and the paleontological data are not at all the same kind of things.
“I’m religious,” Sue Bussey says, “and I know God made it all, but I don’t know or care if he made it in billions of years, or if he put time zones in there to make it look like billions of years.”
That’s a little better. The evidence is the evidence, and Ms. Bussey believes that God made it. I think that she’s wrong, but at least she’s putting her apples in with the rest of the fruit.
Okay, I’ve gotten this post out of my system again. I promise that I won’t write it for a third time until the same year and a half has passed between this one and the next as passed between the first version and this one.