In order to understand what a fallacy is one must understand what an argument is.
An argument consists of one or more premises and one conclusion. A premise is a statement (a sentence that is either true or false) that is offered in support of the claim being made, which is the conclusion (which is also a sentence that is either true of false).
There are two main types of arguments: deductive and inductive.
A deductive argument is an argument such that the premises provide complete support for the conclusion.
An inductive argument is an argument such that the premises provide some degree of support (but less than complete support) for the conclusion.
Fallacies are defects that weaken arguments. A fallacy is, very generally, an error in reasoning.
Some fallacies with examples and tip to avoid them:
Making assumptions about a whole group or range of cases based on a sample that is inadequate.
Example: My roommate said his Constitutional Law class is hard, and the one I am in is hard, too. So, all Constitutional Law class is hard.
Tip: Ask yourself whether you are relying on the opinions or experiences of just a few people, or your own experience in just in a few situations. If so, consider whether you need more evidence, or perhaps a less sweeping conclusion.
Missing the point
The premises of an argument do support a particular conclusion- but not the conclusion that the arguer actually draws.
Example: “The seriousness of a punishment should match the seriousness of the crime. Right now, the punishment for drunk driving may simply be fine. But drunk driving is a very serious crime that can kill innocent people. So the death penalty should be the punishment for drunk driving.” The argument actually supports several conclusions- “The punishment for drunk driving should be very serious” in particular- but it does not support the claim that the death penalty, specifically, is warranted.
Tip: Separate your premises from your conclusion. Looking at the premises ask yourself what conclusion an objective person would reach after reading them. Looking at your conclusion, ask yourself what kind of evidence would be required to support such a conclusion, and then see if you’ve actually given that evidence. Missing the point often occurs when a sweeping or extreme conclusion is being drawn, so be careful if you know you are claiming something big.
Post hoc (Also called false cause)
It came from Latin phrase “post hoc, ergo propter hoc” which translates as “After this, therefore because of this.”
Example: “President Bush raised taxes, and then the rate of violent crime went up. Bush is responsible for the rise in crime.” The increase of taxes might or might not be one factor in the rising crime rates, but the argument hasn’t shown us that one caused the other.
Tip: To avoid this fallacy, the arguer need to give some explanation of the process by which the tax increase is supposed to have produced higher crime rates.
The arguer claims that a sort of chain reaction, usually ending in some dreadful consequence, will take place, but there is really not enough evidence for that assumption. The arguer asserts that if we take even one step onto the ‘slippery slope’ we will end up sliding all the way to the bottom; he or she assumes we can’t stop halfway down the hill.
Example: “Animal experimentation reduces our respect for life. If we don’t respect life, we are likely to be more and more tolerant of violent acts like war and murder. Soon our society will become a battlefield in which everyone constantly fears for their lives. It will be the end of civilization. To prevent this terrible consequence, we should make animal experimentation illegal right now.” Since animal experimentation has been legal for some time and civilization has not yet ended, it seems particularly clear that this chain of events won’t necessarily take place. Even if we believe that experimenting on animals reduces respect for life, and loss of respect for life makes us more tolerant of violence, that may be the spot on the hillside at which things stop- we may not slide all the way down to the end of civilization. We have not yet been given sufficient reason to accept the arguer’s conclusion that we must make animal experimentation illegal right now.
Tip: Check your argument for chains of consequences. Make sure these chains are reasonable.
If the two things are being compared are not really alike in the relevant respect, the analogy is a weak one, and the argument that relies on that weak analogy commits the fallacy of weak analogy.
Example: “Guns are like hammers-they are both tools with metal parts that could be use to kill someone. So, if buying of the hammer is not restricted, it is illogical to restrict the buying of a gun.” But by using guns, one can kill several people from distance which is not possible by hammer. So the analogy is a weak one.
Tip: Identify what properties are important to the claim you are making, and see whether the two things you are comparing both shares those properties.
Appeal to authority
Often we add strength to our arguments by referring to respected sources or authorities and explaining their positions on the issues we are discussing.
Example: “We should abolish the death penalty. Many respected people, such as Film Actor Riaz has stated his opinion about it.” Riaz may be a big star in Bangla film but there is no reason why anyone should move for his opinion- while he is not a bigger authority on the death penalty then the arguer himself.
Tip: There are two ways to avoid this fallacy. First, make sure that the authorities you cite are experts on the subject you are discussing. Second, give an explanation why he gave such opinion.
The Latin name means “to the people”. There are several versions of ad populum fallacy, but what they all have in common is that in them, the arguer takes advantage of the desire of the most of the people and uses that desire to get the audience to accept his or her argument. One of the most common versions is the bandwagon fallacy, in which the arguer tries to convince the audience to do or believe something because everyone else (supposedly) does.
Example: God must exist. After all, I just saw a poll that says 85% of all Americans believe in God.
Tip: Make sure you are not recommending that your audience believe your conclusion because everyone else believes it or people will like you better if you believe it. Keep in mind that the popular opinion is not always the right one!
Appeal to pity
When arguer tries to get people to accept a conclusion by making them feel sorry for someone.
Example: “Please Sir, give me A in my exam. My mother was sick, we changed our house, I have had a cold. It was really hard for me to study.” The conclusion here is “you should give me an A”. But the criteria for getting an A have to do with learning and applying the material from the course; the principle the arguer wants us to accept is clearly unacceptable.
Tip: Make sure you are not trying to get your audience to agree with you by making them feel sorry for someone.
Appeal to ignorance
In this fallacy, the arguer says, ‘Look, there’s no conclusive evidence on the issue at hand. Therefore, you should accept my conclusion on this issue.’
Example: “People have been trying to prove that God exists. But no one has yet been able to prove it. Therefore, God does not exist.” In this case, the arguer tries to use the lack of evidence as support for a positive claim about the truth of a conclusion.
There is one exception to this. If qualified researchers have used well-thought-out methods to search for something for a long time, they haven’t found it, and it’s the kind of thing people ought to be able to find, then the fact that they haven’t found it constitutes some evidence that it doesn’t exist.
Tip: Look closely at arguments where you point out a lack of evidence and then draw a conclusion from that lack of evidence.
One way of making our arguments stronger is to anticipate and respond in advance to the arguments that an opponent might make. In the straw man fallacy, the arguer sets up a wimpy version of the opponent’s position and tries to score points by knocking it down. But just as being able to knock down a straw man, isn’t very impressive.
Example: “Senator Jones says that we should not fund the attack submarine program. I disagree entirely. I can't understand why he wants to leave us defenceless like that.” Here, the arguer thought in advance that the senator Jones is trying to make the country defenceless and he opposes his thinking while this is not the fact.
Tip: Be charitable to your opponents. State their arguments as strongly and accurately as possible. If you can knock down even the best version of an opponent’s argument, then you’ve really accomplished something.
A Red Herring is a fallacy in which an irrelevant topic is presented in order to divert attention from the original issue. The basic idea is to "win" an argument by leading attention away from the argument and to another topic.
Example: "Argument" for making grad school requirements stricter:
"I think there is great merit in making the requirements stricter for the graduate students. I recommend that you support it, too. After all, we are in a budget crisis and we do not want our salaries affected.”
Tip: Try laying your premises and conclusion out in an outline-like form. How many issues do you see being raised in your argument? Can you explain how each premise supports the conclusion?
In false, dichotomy, the arguer sets up the situation so it looks like there are only two choices. The arguer then eliminates one of the choices, so it seems that we are left with only one option: the one the arguer wanted us to pick in the first place.
Example: Either 1+1=4 or 1+1=12.
It is not the case that 1+1=4.
Tip: Examine the arguments. If I am saying that we have to choose between just two options, is that really so? Or are there other alternatives I haven’t mentioned? If there are other alternatives, I should not just ignore them- I have to explain why those, too, should be ruled out.
Equivocation is sliding between two or more different meanings of a single word or phrase that is important to the argument.
Example: “Giving money to charity is the right thing to do. So charities have a right to our money.” Right has two meanings- a) correct or good and b) claim.
Tip: I have to identify the most important words and phrases in my argument and ask myself whether they could have more than one meaning. If they could, be sure you aren’t slipping and sliding between those meanings.
How to find fallacies in writing?
- Pretend that you disagree with the conclusion you’re defending.
- List your main points.
- Learn which type of fallacies you’re especially prone to.
- Be aware that broad claims need more proof than narrow ones.
- Double check your characterizations of others.