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Post Hoc Ergo Propter Hoc Again

by Hans Bluedorn

Post-Hoc-Ergo-Propter-Hoc Sighting in Time Magazine!

I have received reports of yet another sighting of the Post-Hoc-Ergo-Propter-Hoc logical fallacy–this time hiding in TIME's August 27th issue.

Yes, in yet another sordid TIME article on homeschooling, the magazine has done it again–and post hoc ergo propter hoc wasn't the only fallacy seen in that issue. Other notable fallacies–as well as a few out-and-out lies–were noticed in the cover article, "Home Sweet School," written about the current upsurge in homeschooling.

Excerpts from the article:

"In some school districts, so many parents are pulling their children out to teach them at home that the districts are bleeding millions of dollars in per-pupil funding. Aside from money, the drain of families is eroding something more precious: public confidence in schools."

"Thomas Jefferson and the other early American crusaders for public education believed the schools would help sustain democracy by bringing everyone together to share values and learn a common history. . . ."

"Home schooling forsakes all that by defining education not as the pursuit of an entire community but as the work of one family and its chosen circle. . . .Home schooling may turn out better students, but does it create better citizens?"

"'Homeschooling is a social threat to public education,' says Chris Lubienski, who teaches at Iowa State University's College of Education. 'It is taking some of the most affluent and articulate out of the system. These are the parents who know how to get things done with administrators.'"

In order to find the post hoc ergo propter hoc in this, you have to look closely. Notice two sentences: "Aside from money, the drain of families is eroding something more precious: public confidence in schools," and "'Homeschooling. . . is taking some of the most affluent and articulate out of the system.'"

So–if I understand these people correctly, we are to suppose a cause-and-effect relationship, where people taking their children out of public schools causes low public confidence in the schools and the removal of the "most affluent."

That is, they are claiming that homeschooling is CAUSING the EFFECT–the erosion of public confidence in schools and the removal of the most affluent out of the schools, rather than acknowledging the possibility that erosion of confidence in schools is encouraging the most affluent (who have more educational options open to them) to leave the schools.

This reasoning is clearly post hoc ergo propter hoc (which means in Latin: after this therefore because of this), in which someone assumes that since one thing happened before another, the first thing caused the second.

Example: It's obvious Bill Clinton helped our economy. First he became president, then our economy got better.

Post hoc ergo propter hoc errors also occur when we assume that since two things happen at the SAME time, or can be connected in some way, one caused the other: A and B happen at the same time, therefore A caused B. This ignores other possibilities. B, as far as we know, might have caused A, or a mysterious and conspiring W, M and P may be masterminding the whole plot. Example: Poverty makes people commit crimes because most criminals are poor.

This is wrong because it is also possible that being a criminal would make you poor, or that choosing to be a nasty person might make you both poor and a criminal.

The author of the article is probably trying to convince people with both methods of post hoc ergo propter hoc–whichever one he can get away with.

"Aside from money, the drain of families is eroding something more precious: public confidence in schools."

Among a host of equally-plausible cause-and-effect scenarios, TIME only considers one of them.

It is just as possible, perhaps more plausible, that erosion of confidence in public schools is causing people to homeschool.

Later on in the TIME article, we read: "According to the Federal Government, up to three quarters of the families that home school today say they do so primarily because, like so many of us, they are worried about the quality of their children's education."

Where do these children normally get their education – or un-education? The public school.

This seems to be saying that families are leaving the school system because they have no confidence in it – not the other way around, yet the author insists on making homeschoolers the problem.

Now, it is true that this could be a downward spiral. Loss of confidence in the schools make families homeschool, which makes the schools worse, which makes people loose more confidence, which makes more people homeschool, which makes...........till everyone gets dizzy.

However, what we are dealing with here in this magazine article is not a belief in the graveyard spiral. We are dealing with an argument to a hidden presupposition.

In the last Logic Loop, I briefly discussed the importance of assumptions and how they determine every conclusion you make. I called it "presuppositional bias."

If I always presupposed (that is, I always assumed) that food is bad for me, and will ultimately kill me – that is, if I keep on eating it – then you could guess that almost all the decisions I would make in my inevitably short life would be directed by that single presupposition.

But, don't you bother arguing with me about it. When someone has duped themselves in that way, it is no use to argue, their mind is made up. I will even show you ample proof of my claim. I could remark that every person who has ever lived (so far) ate food pretty near all their life, and they all died.

"Now," I say, "if that ain't proof, I don't know what is." No matter what evidence came along to the contrary, I would snatch it up and turn it around to support my presupposition.

That may sound silly, but we all do it in one way or the other. Presuppositions can get into every nook and cranny of the way we think. We all would rather buy the name brand laundry soap, if we had the money, rather than the generic product, because we assume (another word for presuppose) that the company that advertised on TV must make a better soap.

You see how the presuppositions we have will determine the way we think? We pick up presuppositions in the most unnoticeable manner. Did we ever sit down and think about laundry soap and whether good advertising companies make better soaps. No. We picked that up without noticing.

Most of the time, we don't even know what presuppositions we have, so we certainly don't know what conclusions they are driving us to.

So, to get back to the article, what are the presuppositions of the author of this article?

The author of the article certainly knows that the public schools were bad before homeschooling came along. His claim is ridiculous and he knows it.

Since he knows it's wrong and says it anyway, he is lying. This may be a case of someone telling a bold lie in the hope that its very boldness will cause people to believe it.

The author of this TIME magazine article post-hoced-ergo-propter-hoced that homeschooling caused loss of confidence in public schools because he first presupposed that public schools were the good and normal thing, and that homeschoolers were the deviant ones–deviant from "normal" culture.

This goes back to what I say about presuppositions. His presuppositions cause him to be willing to lie, which causes him to convince others of it with the fallacy of post hoc ergo propter hoc. So, the problem isn't just with a presupposition, it is also an ethical problem.

So, my point, if you haven't picked it up somewhere along here, is this: Presuppositions determine conclusions, and bad presuppositions can cause you to commit fallacies. If we want good conclusions we need to examine our presuppositions and make sure they are the ones we wish to have.

When reading the entire article, this presupposition bias becomes fairly obvious. Below, I will quote some others in the article, and ask you to name what fallacies they are.

So, to end with thought-provoking questions: What are our presuppositions? And what evidence do we have for them? (We don't want to ask: "What evidence can I find to support my presuppositions?" Anybody can come up with evidence to support an argument. Proof is harder.)

Other fallacies in the article.

This first quote isn't necessarily a fallacy; it is, however, something which has several problems. I would like your comments on it. Specifically: What is the absurd conclusion that he is trying to prove.

"Despite its growing acceptance, there are nagging shortcomings to home schooling. If you spend time with home schoolers, you get a sense that some of them have missed out on whole swaths of childhood; the admirable efforts by their parents to ensure their education and safety sometimes seem to have gone too far.

"In 1992, psychotherapist Larry Shyers did a study while at the University of Florida in which he closely examined the behavior of 35 home schoolers and 35 public schoolers. He found that home schoolers were generally more patient and less competitive. They tended to introduce themselves to one another more; they didn't fight as much. And the home schoolers were much more prone to exchange addresses and phone numbers.

"In short, they behaved like miniature adults. Which is great, unless you believe that kids should be kids before they are adults. . . . One could argue that kids need to get into a certain amount of trouble to learn how to handle temptations and their consequences."

This second quote from the article is a fallacy. I will list several fallacy types below. Pick which one you think this is, and email me your answer.

"The same blinkered approach can extend to academics. "I make pretty much all the decisions about what to study," says Maren McKee, 15, of Naperville, Ill., who left public school after third grade. "I wasn't interested in math or composition, so I didn't really do it. I liked to dance." But now McKee, who is dyslexic, realizes she will need more than dance steps to get into college. "My mom and I are going to spend this whole year on math and learning to write," she says, perhaps not fully appreciating that both of those skills can take much longer than a year to learn.

"Brie Finegold, 22, a graduate of the University of North Texas, says she did fine without the traditional classroom. 'I got to do volunteer work at the food bank at my synagogue and apprentice to a dance company when I was a teenager, when others my age were sitting in classrooms,' she says. But volunteering and dancing aren't necessarily better than chemistry and poetry. "The basic function of a liberal education is to expose people to fields they normally wouldn't investigate. Whether you believe the purpose of education is to shape one's character in a democracy or to prepare Johnny for his job, neither is accomplished when kids get to study only what they want."

The entire article is available online at:

Fallacies to choose from:

* Hasty Generalization: Generalizing about something without enough of a sample:

Ex: All Fords are bad. I once owned a Ford and it was junk.

Ex. I don't think anybody lives in North Dakota. Everybody I ever talked to who was from there doesn't live there anymore.

* Appeal to Ignorance: Saying something is true because it hasn't yet been proven false:

Ex: You can't prove you didn't steal that car, so you must be guilty.

Ex: No evidence has been found that there isn't life on other planets. Therefore, we are not alone in the universe.

* Genetic Ad Hominem: an attempt to prove an argument false by attacking its source (its genesis), not the argument itself.

Ex: The only reason you disagree with me is because you were abused as a child.

Ex: That church cannot possibly be good. It was formed by an unregenerate heretic.

Waiting for your answers,

Copyright September 05, 2001, all rights reserved. 11463 views

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