# Incoherent Arguments Cannot be Right

There are four cards on the desk in front of you: they are labeled A, 4, K, and 5. Your teacher tells you that any card with a vowel on one side will have an even number on the other side. You are supposed to test that rule. Which cards would you turn over to determine whether the rule is true?

If you are like most people, you’d turn over the A and the 4. Would this tell you whether the rule holds?

No, because it doesn’t matter what’s on the other side of the 4; whether that’s a vowel or consonant is immaterial to the rule. For a proper test, you need to turn over the 5—because if you had found a vowel on the obverse, then that would have falsified the rule.

People are notoriously bad at solving this type of logical problem, which goes by rather tortuous names such as “modus tollens” or “denying the consequent”.  I prefer to call it the Most Frightfully Boring Task, or MFBT.

Now for something completely different.

Imagine you are a liquor inspector tasked to enforce the legal age of 18. Suppose you walk into a pub and discover four fellows around a table. One is drinking coke, the second beer. The remaining two are sucking some unknown beverage out of two paper bags, but they very helpfully wear their IDs around their necks. One is 22, the other 16.

How would you enforce the law?

Easy—you ask the beer drinker for an ID and you look inside the 16 year-old’s bag.

Dead easy, anybody can do it.

Amazingly, the liquor-law enforcement is logically identical to the MFBT! Even though people struggle with the vowels and numbers, they have no problem being logical when the task is couched in everyday terms.

This is a fundamental aspect of human cognition. We reason badly in the abstract but we are quite smart within the context of everyday life.

This human frailty is routinely exploited by those who are trying to confuse the public about the well-established scientific fact that the Earth is warming, largely due to human CO2 emissions.

Their ignorance or ideologically-driven mendacity is easily revealed by translating denier illogic into an everyday equivalent—where all of us can instantly recognize some of the nonsense for what it is.

For starters, suppose that while you check his paper bag, the 16-year old suddenly says: “Apples don’t exist.” While your eyebrows are still rising, he adds, “but they grow naturally on trees!”

What? “Apples don’t exist but they grow naturally on trees?”

Needless to say, no one would trust that individual with the lives of their children if their future depended on logical coherence. Instead, we’d all wonder what had been inside his paper bag.

Now suppose the beer drinker says while handing over his ID: “The price of sheep is unknown, but I’d buy some now because they are cheap.”

What? “The price of sheep is unknown but they are cheap?”

One more reason maybe to raise the drinking age to post-primary-school logical literacy.  And no point trusting that fellow with your kids’ lives either, if their future depended on logical coherence.

Now here is the problem: Your kids’ future, and the future of their kids, very much depends on logical coherence—or more precisely, it very much hinges on protecting them and their future from the incoherent illogical mutterings just presented. This is because the sum total of the arguments made by so-called climate “skeptics” is an incoherent muddle of contradictions.

On a Monday morning your resident “skeptic” might tell you that global warming does not exist. On the Monday afternoon, she may tell you that the warming is all natural, just the same way that non-existent apples grow naturally on trees.

Nothing this incoherent can be right.

And on Tuesday, a so-called “skeptic” may drift into town and make claims about the temperature record not being accurate by showing you a picture book of thermometers. He might also assure you that there is nothing to worry about because it hasn’t been warming in the last 23 days anyhow. So the sheep are cheap but no one knows their price.

Nothing this incoherent can be right.

By Wednesday morning, your excited “skeptic” may have invented the possibility that the sun is causing global warming, and by afternoon tea time it might be cosmic rays, or El Niño, or Inspector Clouseau or whatever.

Nothing this incoherent can be right.

And nothing this incoherent is “skepticism”—instead, it reflects either ignorance, denial, or mendacious propaganda that can gain traction only by hiding its incoherence under the cloak of an abstract MFBT that people are known to find challenging.

As a final illustration, suppose you go to hospital after returning from the jungles of New Guinea with a temperature. You are stunned to hear the young intern opine that you couldn’t possibly have a tropical disease, because when you last visited the emergency room with a fever in 1976, you had the measles.

I bet you’d call your lawyer and file a malpractice suit the next day.

And yet, exactly the same malpractice is perpetuated by those who claim that the present warming also happened 800 years ago (or 8000 or 80000 or whatever comes in handy) and that we therefore have nothing to worry about.

Ignoring the fact that present temperatures are likely the highest observed for nearly a millennium, this logic is like saying that your childhood measles prevent you from having a tropical disease now.

It’s like saying that because bush fires were caused by lightning strikes before people came to Australia, arsonists now don’t exist.

Nothing this illogical can be right.

It may strain credulity that anyone could be so muddled; but in fact, it takes little effort to go to a “skeptic” website and dig out dozens if not hundreds of incoherent mutterings and egregious flaws in elementary logic.

If you don’t like to infect your computer with links from the web’s netherworld, then even the ABC Drum occasionally offers up eruptions of illogical and involuntary hilarity. An individual who calls himself a “research fellow” at the “Institute for Public Analysis” recently offered up the medieval warm period as evidence against anthropogenic warming: Because there were vineyards in Greenland in the middle ages, the Arctic isn’t melting today because … who knows … but somehow it’s not CO2 that causes the Arctic to melt because the Vikings drank beer out of beaver skulls. Or something like that.

The medieval warm period is as relevant to current warming as ancient lighting-caused bush fires are to today’s arsonists.

The medieval warm period is as relevant to current warming as your childhood measles are to today’s tropical disease.

The same symptom can have multiple causes: Today’s fever may be a virus whereas your childhood fever was related to the measles. Today’s warming is caused by CO2 whereas previous warming episodes were caused by other factors such as variation in insolation.

The medieval warm period, if anything, tells us that the climate is sensitive to forcings such as greenhouse gas emissions, which is something that real research fellows at actual universities know very well. It is only “research fellows” at the “Institute for Public Analysis” who, securely anchored in their well-funded ignorance, cite the medieval warm period to indulge in muddled logical travesties.

The Institute for Public Analysis, it will be recalled, is known to be funded by mining, resource and tobacco companies. Although large expenditures for propaganda are standard corporate wastage, in this instance \$20 worth of vermouth in a paper bag would have been sufficient to elicit the same logic.