The Actual Name for Trump’s Logical Fallacy… “Modus Morons” (Seriously)

The Actual Name for Trump’s Logical Fallacy… “Modus Morons” (Seriously) May 27, 2020

In the last post, I mentioned Donald Trump’s comment that he considered it is a “badge of honor” that the U.S. has the highest number of coronavirus cases in the world. I looked at the problem with his appeal to “honor.” Today, I want to highlight a fundamental problem with his logic.

President Trump said,

“I look at that [high number of cases] in a certain respect as being a good thing, because it means our testing is much better. So, if we were testing a million people instead of 14 million people, it would have far few cases, right?”

How might high case number mean testing has improved? Only two possibilities exist.

(1) Increased case numbers          —–> (implies)          better testing


(2) Better testing                 —–> (implies)                    increased case numbers

The first option cannot be true. In any country, case numbers can sky-rocket long before testing capacity catches up. China and the United States are a few obvious examples. A country can have so many cases that most people that get tested received positive tests. This scenario, of course, is not something to celebrate.

The second option seems to reflect what Trump has in mind. In short, his thinking seems to be, “We’re doing more testing, so the effect will be increased case numbers.” The problem, however, is that Trump appears commits what logicians call “modus morons.” (I’m not kidding…. that’s a real term with a real meaning. Google it.)

I’ll explain.

The term “modus morons” is a play-on-words from two other basic rules of logic (i.e., modus ponens, modus tollens). In logic, the following represents good logic structures.

Modus Ponens

A –> B      (A implies B)
A                (A)
∴ B           (therefore B)

Modus Tollens

A –> B      (A implies B)
~B             (not B)
~A        (therefore, not A)

What is “modus morons”? I refers to the common practice of affirming B (the consequent) and then concluding A (the antecedent). Accordingly, the structure looks like this:

A –> B      (A implies B)
B                (B)
 A          (therefore, A)

For example,

If something is a kangaroo, it is a mammal.
I am a mammal.
Therefore, I am a kangaroo.

If you are a women, you are a human
You are a human.
Therefore, you are a women.

These are obvious examples of invalid conclusions and of “modus morons.” Some people nickname this reasoning “modus bogus” and “hokus ponens.”

Let’s return to Trump’s assertion: Better testing implies there will be increased case numbers. At one level, this is certainly true. However, Trump draws an inference that moves in the wrong direction. He accepts the basic fact that reported case numbers have increased, then he concludes, “it means our testing is much better.” In other words,

Better testing —> Increased case numbers
Increased case numbers
 Testing is better.

Nope. That’s modus morons.


Photo Credit: Pixabay

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