Can you outsmart the apples and oranges fallacy? - Elizabeth Cox

Baking apple pie? Discount orange warehouse has you covered! A fruit’s a fruit, right?

It’s 1988, and scientist James Hansen has just testified to the United States Congress that global warming trends are caused by human activity, and will pose an increasing threat to humanity in the future. Well, well. That’s unusually prescient for a human.

Looking for a wedding dress? Try a new take on a timeless classic. It’s sleek, flattering and modest—just like the traditional dress. Commercials. Could anything be more insufferable?

It’s 1997, and the United States Senate has called a hearing about global warming. Some expert witnesses point out that past periods in Earth’s history were warmer than the 20th century. Because such variations existed long before humans, the witnesses claim the current warming trend is also the result of natural variation.

Ah, there is something more insufferable than a commercial. Luckily for the humans, there’s one more expert witness. What are you looking at? We’re all dressed. At least we are by the logic you just used.

It’s as if you were to say apples and oranges are both fruits, therefore they taste the same. Or that underwear, wedding dresses, and suits are all clothes, therefore, they’re all equally appropriate attire for a Senate hearing. The European wars of the 19th century and World War I were all wars, right? So World War I couldn’t be any more devastating than those other wars, could it?

Let’s say two people have a fever. They must have the same disease that’s causing that fever, right? Of course not. One fever could be caused by chicken pox, the other by influenza, or any number of other infections.

Like your claim about rising global temperatures, these claims make a false analogy. You're assuming that because two phenomena share a characteristic, in this case warming, they are analogous in other ways, like the cause of that warming. But there’s no evidence that that’s the case.

Yes, there have been other warm periods in Earth’s history—no one’s disputing that the climate fluctuates. But let's take a closer look at some of those older examples of global warming, shall we?

The Cretaceous Hot Greenhouse, 92 million years ago, was so warm, forests covered Antarctica. Volcanic activity was likely responsible for boosting atmospheric carbon dioxide and creating a greenhouse effect. The Paleocene-Eocene Thermal Maximum, 55 million years ago, was so warm, crocodiles swam the waters of the Arctic Circle.

This warming may have been caused by the drying of inland seas and release of methane, a potent greenhouse gas, from ocean sediments. Even among these other warm periods, you’re making a false analogy. Yes, they had natural causes. But each had a different cause, and involved a different amount and duration of warming.

They’re as dissimilar as they are similar. Taking them together, all we can reasonably conclude is that the Earth’s climate seems to change in response to conditions on the planet.

Today, human activity is a dominant force shaping conditions on your planet, so the possibility that it’s driving global warming can’t be dismissed out of hand.

I’ll grant that the more complicated something is, the easier it is to make a mistaken analogy. That’s especially true because there are many different types of false analogy: that similar symptoms must share a cause, that similar actions must lead to similar consequences, and countless others.

Most false analogies you’ll come across are far less obvious than those comparing apples to oranges, and climate is notoriously complex. It requires careful, rigorous study and evidence collection—and making a false analogy like this only impedes that process.

It’s 2013, and the United Nations Intergovernmental Panel on Climate Change has found, aggregating decades of research, that there is more than a 95% chance the global warming trend since the mid-20th century has been driven by human activity, namely the burning of fossil fuels.

You’re both pets, and he likes living in water, so you should, too.