Saturday, April 24, 2010

The Line Drawing Fallacy

Take a second and look at these four pictures:
image1 image2 image3 image4
For those of you who aren’t familiar with the cars here, there is a Volkswagen Thing and a Jeep. The question now is “Which is which?” The one that looks like a jacked up thing actually is 4-wheel drive and has the motor in the front and the one that looks like the Jeep has the motor in the rear.
These pictures reminded me of a logical fallacy called the Line Drawing Fallacy. I’m going to modify it from the way I first heard it in order to fit these pictures. Let’s suppose that I have two cars in the garage. A Volkswagen on the right and a Jeep on the left. One day I decide it would be fun to start swapping parts form one car and sticking them on the other. I start with a bumper. Then I move to fenders. Then on to the to more serious stuff, the suspension, the wheels, drive train, frame and on and on. When I’m finished I will have a complete Jeep on the right and a complete Volkswagen on the left. Now for the big question. At what point in the process did the Jeep become the VW and the VW become the Jeep? Was it when they swapped the frame? The motor? The hood emblem? So far there isn’t a logical fallacy, just a philosophical conundrum. But what if I challenged the identity of the cars like this? Since you can’t exactly answer when the VW became the Jeep then the car on the right must still be the VW even though it now has every single part of the original Jeep.
It kind of sounds absurd when you are talking about cars. Nevertheless, people make this fallacy of reason frequently. I hear it frequently in the debate about the definition of life. Some argue that since you can’t really define when a person became alive then we must have always been alive. The most egregious abuse of this concept came years ago during the trial of the officers who assaulted Rodney King. An attorney asked the question, “At what point did the officers use excessive force? Was it after the first hit, the second, the third?” He then went on to tell the jury that if they couldn’t define exactly when it became excessive then they couldn’t accurately define what excessive force meant and the officer was not guilty. The other attorney, recognizing the fallacy, approached the jury and took a book and slammed it against the table the exact number of times that King was hit. I think it was 23 times. He then said, “I don’t care exactly when their actions became excessive. It was somewhere between the first hit and the 23rd.” And that’s the correct answer here too. There are multiple shades of gray in our world. But that doesn’t mean that black is the same as white or that Jeeps are the same as VWs.


  1. Wow, philosophy and car shows. You're blowing my mind. Hope you had a good time at the show. Sorry to hear about your old van. Let me know if you need any help on it (not that I know a thing about them).

    randolph (dot) jim (at) gmail (dot) com

  2. Anonymous10:12 PM

    I like your car illustration, it's much better in my opinion then the lightness/darkness example that is commonly used.