What kind of fallacy is said if one has assumed that something is caused by another thing just because it is preceded by it?

Post hoc ergo propter hoc is the Latin name of a common fallacy (i.e. a bad argument) in academic writing. Also known as ‘assuming the cause’, it arises when we get confused about what causes something. For more on what this fallacy involves and how to avoid it in your writing, read on below.

What Is the Post Hoc Ergo Proctor Hoc Fallacy?

Post hoc ergo proctor hoc translates as ‘after this, therefore because of this’. In other words, this fallacy is the mistake of assuming that the order of events implies causation. We can set it out in abstract form as follows:

X occurred before Y, so X must have caused Y.

This is also known as the post hoc fallacy or ‘assuming the cause’.

A similar error is assuming that correlation implies causation, where a pattern of coincidence is taken to show that there must be a causal connection between two phenomena. But here we’re focused on the order of events.

Let’s take a look at some examples of this fallacy in action.

Examples of Post Hoc Ergo Proctor Hoc

This fallacy always begins with an observation of two events occurring in sequence. The mistake is then assuming that the first event caused the second. For instance:

Levels of petty crime went down after the town council raised taxes. This shows that raising taxes is an effective way of reducing crime.

Here, we see that two events occurred in sequence, so we might jump to the conclusion that the first (raising taxes) caused the second (reduced crime). But there is nothing in the statement above that establishes a connection between tax and crime (we don’t even know how the taxes raised were spent). And many other factors may affect crime levels, from policing policy to unemployment levels.

As such, we cannot assume the crime level went down purely because the taxes went up! Unless we know how the two are connected, we can’t draw any conclusions. If we do, we end up fallaciously ‘assuming the cause’.

Most superstitions are based on some form of the post hoc fallacy, too. Take the belief that breaking a mirror leads to bad luck, for instance:

I broke a mirror yesterday, and I’ve been unlucky all day today.

In reality, any bad luck you experience after breaking a mirror is mere coincidence, since there is no causal relationship between mirrors and luck! But if someone breaks a mirror and then notices other things are going wrong afterwards, they might assume that the breakage caused the subsequent bad luck.

The error here lies in imagining a causal relationship where there isn’t one.

Is It Always Wrong to Assume a Cause?

So, is it always wrong to assume a causal relationship between successive events? Not entirely! Causes do precede their effects. Thus, observing that one thing happens before another thing may be reason enough to investigate it further.

However, in an academic context, you need more than just an observation of one thing happening after another to claim a causal relationship. You also need to show that X causing Y is the best explanation available based on the evidence.

How you do this will depend on what you are studying. A sociologist, for instance, might look at statistical data to establish a pattern of cause and effect between different social phenomena (e.g. taxes and crime rates). And in the hard sciences, it might involve conducting an experiment that controls for different variables, allowing you to focus on proving (or disproving) a relationship of cause and effect.

In all cases, though, observing that one thing happens after another should only ever be a jumping off point for investigation. If you simply assume that one event causes another based on their sequence, you’ll be in fallacy territory!

How to Avoid the Fallacy

As noted above, the key to avoiding the post hoc ergo propter hoc fallacy in your work is to base your arguments on evidence as much as possible.

Noticing that one event precedes another event may raise questions, but you need to look at how the two events are related – and whether other factors may be involved or offer a better explanation – to establish a causal connection.

It also helps if you have your writing proofread, since this ensures you can express your ideas clearly. To give our academic proofreading services a try for free, upload a 500-word document today and find out how it works.

Explanation of Fallacious Arguments

 The different kinds of fallacious arguments are listed below.  There are other kinds of fallacies or bad arguments that we do not consider here.  One example is a self-contradictory argument.  Another is one in which the reasons given have nothing to do with the conclusion

Many arguments will simultaneously exhibit two or more of the following traits.  So you need to be able to recognize the fallacies AND be able to give good explanations for WHY that particular fallacy is present.

Another thing to remember is that the presence of a fallacy does not necessarily mean that a person's conclusion is not true.  If I say "Since the sky is green and made of moldy Swiss cheese, we know that 2 + 2 = 4."  The argument is poor, but the conclusion is still true.

1.         Personal Attack (ad hominem) - Ad hominem is a Latin term that literally means "to the man."  That describes the fallacy well because the argument about the issue is ignored and instead an attack is made on the person involved instead.  This is one of the easiest to spot.  Just pay attention to the focus of the argument.  Is it the topic?  Or is it the person arguing the other position.

2.         Circular Reasoning - Sometimes people will make an argument for something by simply restating what they are trying to argue.  "We should help the underprivileged because we have an obligation to watch out for those less fortunate than ourselves."  Notice that the two parts of the statement "We should help the underprivileged" and "we have an obligation to watch out for those less fortunate than ourselves"  are merely the same thing said in two different ways.  This basically says "I think this is true because it's true."

3.         Diversion (Red Herring) - A red herring was sometimes dragged across a trail to divert hunting dogs from the scent.  In the same way a "red herring" argument diverts the person's attention from the actual discussion to some side issue.  "Bill Clinton should not have been charged with perjury because he did a good job with the economy."  The economy, whether good or bad, has absolutely nothing to do with whether or not the former president should have been charged with perjury.

4.         Straw Man - This argument is much the same as the red herring argument.  This one, however, deals with a false caricature of a person or group.  "Bob is a democrat so he obviously supports abortion and gun control, and opposes the death penalty."  Stereotypical "democratic issues" may or may not be ones that Bob supports.  This fallacy involves aligning your opponent with an easier target to attack.

5.         Appeal to Popularity - No one likes to be in the minority on things.  It is much more pleasant to be in agreement with people.  The appeal to popularity tries to argue, truthfully or not, that "most people think this way so you should too."  "More people brush with Crust toothpaste."  The hope is that you'll think that the fact (if it is indeed a fact) that more people do or believe something implies that that action or belief is one you should embrace. 

6.         False Cause - A "false cause" argument basically says that since Event A preceded Event B, then Event A must have caused Event B.  Superstitions are classic examples of false cause.  A person saw a black cat cross his path and then something bad happened.  "Aha!, the black cat crossing my path caused this bad thing to happen."  That is obviously absurd but similar things are embraced quite regularly by otherwise intelligent people.  Some cases of false cause are not as obvious.  "I took some aspirin and my headache went away so the aspirin cured my headache."  That may be true, but some headaches go away all on their own.  It is possible that the aspirin had nothing to do with it.

7.         Appeal to Ignorance - This one is often misunderstood.  Sometimes the person making an argument is ignorant or says something that is stupid or ignorant.  That is NOT an appeal to ignorance.  Appeal to ignorance relies on the lack of sufficient knowledge about something to be evidence for one side or the other of the argument.  "We've never shown life can't exist on Mars so there must be life on Mars."  That is an example of appeal to ignorance.  Not knowing the answer to a question does not mean we can assume one or another possible answer.

8.         Hasty Generalization - This is one of the most common fallacies in everyday life.  It is used to perpetuate stereotypes.  I grew up in a town with very few blacks.  About the only blacks that most people in my town heard about were ones on the news who were getting in trouble.  A hasty generalization would be to take that information and conclude that all blacks must be troublemakers.  If I've had a Ford car that was not good it is not reasonable to assume that all Fords are lousy cars.

9.         Limited Choice - Sometimes people will make an argument by saying "option A is a bad one because of these reasons so therefore option B is the best choice."  Well, even if they are right that option A is a bad choice, isn't it possible that there might options C, D or E?  "What's your favorite kind of soda, cola or root beer?"  There are other possibilities that are precluded by the wording of the question.

            Keep in mind, just because the choices are limited does not necessarily mean you have an example of "limited choice."  For instance, if a poll asks "Do you own a motorcycle? Yes or no."  This is not limited choice because "Yes" and "no" are the only choices possible.  If it is really limited choice, then you should be able to identify a choice that really exists but is not included.

10.       Appeal to Emotion - This fallacy is similar in some ways to the appeal to popularity.  It is also VERY common in commercials and advertising.  The idea is to associate a particular argument, product or idea with a very good or very bad feeling or outcome.  We've all seen the commercials where a man uses a particular kind of shampoo and all of a sudden he is surrounded by beautiful women.  The idea is to associate the shampoo and the beautiful women flocking around.  Another way to use this one is in arguing something like "If you ban guns then only criminals will have guns so we'll all be living in fear."  This takes an issue and tries to tie it to a particular, negative emotional situation. 

One thing to note on the usual form of the last example.  "If you ban guns then only criminals will have guns."  This is actually true.  If guns are illegal, then anyone who has a gun is, by definition, a criminal.  The argument actually says nothing.