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Strong Analogies

by Hans Bluedorn

IMPORTANT: Read this email very carefully. At the bottom there is a short quiz which you can take if you like. If you answer all the questions correctly, then you will receive an unimportant and not-so-great prize.

We make an analogy when we compare two things. Two things, like cars.

Bert: "My dad just bought a new car–it's a Ford and has a V-8 engine."

Clyde: "Oh really? My dad just bought a new Ford, and it has a V-8, too. Ours is blue."

Bert: "Hey, ours is blue too."

Clyde: "Boy, our cars are a lot alike. Ours drives very fast. I wonder if yours does?"

Bert: "I don't know yet, but if both our cars are so much alike, our new car must be fast too."

Bert is reasoning by analogy.

Bert is reasoning by analogy because he is comparing things with each other. He notices that both his and Clyde's parent's cars are very similar–they have the same manufacturer, same engine, and same color. Since they are so similar in these things, he reasons, they must be similar in other things–like speed.

Arguing by analogy is useful reasoning–if done properly. Many useful observations can be gained through analogies.

Mr. Smith: "The last time we went to the Jones' for dinner we ate salmon, and we were sick for the rest of the evening. The time before that, when we went to the Jones,' we ate salmon and were sick for the whole evening. Now, the Jones' have invited us over again and they are serving salmon–I'll bet we get sick."

In this analogy Mr. Smith is comparing the last two times they visited the Jones' with this time. We could lay it out like this:

1st evening: visit Jones'...Eat salmon...Get sick.

2nd evening: visit Jones'...Eat salmon...Get sick

This evening: will visit Jones'...Will eat salmon...___________

Mr. Smith sees a pattern and fills in the blank with "will get sick."

While in this article I am mostly dealing with scientific analogies–the kind people use to prove things–there are other types of analogies.

Analogy is also used very effectively by famous authors to make a point.

"The difference between the right word and the almost right word is the difference between lightning and the lightning bug." – Mark Twain

Here, Mark Twain is drawing an analogy comparing the difference between "the right word and the almost right word," and the difference between lightning and a lightning bug.

Poetic analogies, unlike more scientific analogies, aren't supposed to be very precise. They are just used to get a point across elegantly.

So how can we tell if an analogy is strong or weak?

1. If the similarities between the things being compared are major and the differences only minor, then it is a strong analogy.

Let's say, for example, that you are a budding scientist wanting to write your graduate thesis on the long term effects of pop tarts on humans. The only problem is, you can't find enough people, at least, not enough people willing to eat 34 pop tarts a day for one year. So you decide to do the experiment on some kind of animal, hoping the results would be the same.

You pick orangutans. There are a lot of similarities between orangutans and people, at least as far as basic anatomy goes (well, actually, I have been informed that this is not the case, but we'll assume it, so I don't have to come up with another example). Let's say we are both about the same size and have generally the same digestive systems–these similarities are relevant to our study. However, there are some differences between orangutans and humans. Orangutans tend to be a little more hairy and have shorter noses than people. Also, people usually don't dip their fingers in the punch bowl at parties.

But, in regard to our experiment, these differences are minor. The similarities between orangutans and humans are major and the differences probably minor.

If you fed pop tarts to striped cucumber beetles for the proper amount of time, it just wouldn't be the same as if you picked orangutans.

2. If the differences between the things being compared are major and the similarities minor, then we call it a weak analogy. A weak analogy is a logical fallacy.

Let's go back to Clyde and Bert's new automobiles. Suppose their conversation went like this:

Clyde: "Our new car is a blue Ford. It has a 15 gallon gas tank, 5 cup holders and a sun roof. Boy is sure drives fast!"

Bert: "Hey! Our car has all of those things. I'll bet it drives fast too."

Clyde and Bert's new cars do have a lot of similarities. However, color, size of gas tank, and number of cup holders have little to do with the car's speed on the road. Its similarities are only minor. If we found out that the two cars differed in speed related things–Clyde's car had a large engine and was designed by BMW, while Bert's had a small engine and was made for removing garbage–we might say that the differences were major.

The funny thing is, car makers, especially Japanese car makers, use this trick all the time on gullible consumers. They take a cheap underpowered car that can barely accelerate onto the freeway, and give it sleek styling, just like the fast cars, and hope people will draw a weak analogy between the fast cars and their car. "Hey, it looks like it could go really fast!"

Sometimes people come up with very wild analogies.

Clyde: "I think it is all right for governments in developing countries to execute citizens who are against its political goals."

Jenny: "That sounds terrible! Why do you think they should be allowed to do that?"

Clyde: "Hey, if you want to make an omelet you have to break eggs."

Clyde, of course, is being ridiculous. The similarities between a developing nation and breakfast food are so minor it would be a waste of time to mention them.

Quiz Time

So, now that you know everything about analogies, it's time for–you guessed it–a quiz. Reply to this email with your answers typed in just below each question.

In each of the following examples, answer these questions. 1. Is it an analogy? (Some are not.) 2. After examining the similarities and differences, do you think the analogy is strong or weak?

Since the strength of an analogy can sometimes be a matter of opinion, I will be lenient with some of the questions, if you are convincing.

QUESTION 1. Chicago and Detroit are cities of approximately the same size. They are both in the Midwest and are located near a large body of water. I know Chicago has a bad crime problem, so, Detroit must have a bad crime problem too.

QUESTION 2. A cloud is 75% water, a watermelon is 75% water. Therefore, since a plane can fly through a cloud, a plane can fly through a watermelon.

QUESTION 3."The broad mass of a nation ... will more easily fall victim to a big lie than to a small one." – Adolf Hitler

QUESTION 4. Rock music is bad for you. I heard a test was done with cows. They had two milk cows listen to music. One listened to Mozart and the other listened to heavy metal. The one that listened to Mozart produced more milk and acted more contented, while the one that listened to heavy metal ate more, knocked over the milk bucket, and grew a horn.

QUESTION 5. "David Copperfield" was a novel by Charles Dickens, set in England and I hated it. "Oliver Twist" was a novel by Charles Dickens, set in England and I hated it. "Great Expectations" is a novel by Charles Dickens, set in England. I think I will hate it.

QUESTION 6. Let's say you examine 400 engineers all over the world and of that number, 300 have at least 8 pens in their shirt pocket. Therefore, you conclude, 75% of engineers keep at least 8 pens in their shirt pockets.

QUESTION 7. Since a single human cell becomes a grown man over a period of a few years, then surely it can't be impossible for a single-cell organism to become the human race over a period of several million years.



Date: Sat, 15 Dec 2001 04:40:52 EST


I found an example of circular reasoning from an individual from whom I would least expect it. It is a Christian apologist who will remain unnamed so as not to discredit him, because he is one of the best thinkers I have ever encountered and is more logical than I could ever hope to be. I wouldn't want to let one little slip discredit him in anyone's eyes. He was giving reasons to reject the Apocrypha as part of the canon of Scripture. His third reason was as follows: "Some books promote unbiblical concepts, e.g., prayer for the dead (2 Macc. 12:45-46)." The question here pertains to the contents of the canon, and whether or not the Apocrypha is to be considered part of the contents or not. But he assumes already what the canon is to judge the canonicity of the Apocrypha. He is assuming that which he is trying to prove; i.e., that the canon does not include the Apocrypha. If he did not start with this conclusion, he would have no basis to say that the Apocrypha cannot be included because it promotes "unbiblical concepts." If indeed the Apocrypha should be part of the canon (which is the question at hand), then it would be part of the Bible, and thus its teachings could not be considered unbiblical. De facto its teachings would be biblical, and thus could not contradict the Bible, because it would be contradicting itself (this argument of mine presupposes the unity of Scripture). He had already assumed that the Apocrypha is not part of the canon, and then goes on to argue based on this a priori commitment that its teachings are unbiblical. While he made it seem that he moved from a question (whether or not the Apocrypha is part of the canon) to a conclusion, he actually moved from a conclusion to a conclusion, using circular reasoning to "prove" his point. The rabbit was always in the hat just waiting to be pulled out!

–Jason Dulle

Stockton, CA

Here are the answers to last loop's quiz.

QUESTION 1. All plumbers are brilliant. I know a plumber who can calculate Pi to the 289,954th digit. [Generalization. Sample of one. Hasty.]

QUESTION 2. All plumbers are rich. I just went to the international plumbers convention and studied 3,000 plumbers there. They all made over $100,000 a year. [Generalization. Sample of 3,000. Hasty–only rich plumbers would go to an international convention.]

QUESTION 3. My mom teaches people well. Whenever she explains something to me, I understand it perfectly. [Generalization. Sample of one. Hasty.]

QUESTION 4. Some plumbers are brilliant. I'm a plumber, and I know I'm brilliant. [Not a generalization. Some means one or more.]

QUESTION 5. Everything by Charles Dickens is boring. I have read all his novels, and they all put me to sleep. [Generalization. Sample of only Dickens' novels, not short stories, letters, grocery lists, etc. Probably hasty.]

QUESTION 6. There are parts of Alaska that have a high elevation. Mount McKinley is 20,320 feet high. [Not a generalization.]

QUESTION 7. All dogs have fleas. I just finished examining every single dog in the universe, and they all had fleas. [Not a generalization.]

QUESTION 8. A barrel contains 100,000 jelly beans. After shaking up the barrel thoroughly (taking care that none get squished), you extract 5,000 jelly beans. 500 of them are black. Therefore, 10% of the jelly beans in the barrel are black. [Generalization. Sample of 5,000. Probably not hasty.]

QUESTION 9. Commercial airlines are very safe. How many major airline crashes do you hear about every year? Maybe two or three. Compare that with how many flights there are every year. Or compare the number of plane crashes with the number of car crashes! [Generalization, although more like an analogy. The study is very subjective and is based mostly on a feeling of how many plane crashes there are. I would say it is hasty.]

QUESTION 10. Premise: I wore this straw hat several times last week while weeding the garden and I started to sneeze.
Premise: I wore this straw hat when I went to the bonfire, and I started to sneeze.
Premise: I wore this straw hat outside yesterday and I started to sneeze. Conclusion: I'm allergic to this straw hat. [Generalization. Sample of several. Hasty.]

Copyright February 06, 2002, all rights reserved. 16998 views

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