Step 4. Identify Logical Fallacies

A logical fallacy is an argument that seems to present a good case for its conclusion, but for various reasons fails to do so. There are many logical fallacies, so many that we will only discuss one for illustrative purposes and provide a list of a few common fallacies with an online reference for further information. The point we wish to make here is that the existence of a logical fallacy in an argument does not mean the conclusion to the argument must be false or is probably false, it only means that the conclusion is not supported by the fallacious premises. This means when analyzing an argument (assuming it contains more reasons to accept the conclusion than just the fallacious ones), one should point out that part of the argument which is a fallacy, name the fallacy (or explain in your analysis why it is a fallacy), and state the conclusion of the argument is neither strengthened or weakened by the part of the argument that is fallacious.

As usual, it is helpful to illustrate this process by an example. First we need a logical fallacy.

An ad hominem fallacy occurs when some personal characteristic of the arguer is attacked rather than the conclusion of the argument itself.

Example: President Smith just signed a treaty with Bolivia which will open the doors to more trade between those two countries by removing tariffs and other economic obstacles which prevented many companies from doing business with Bolivia. However, these tariffs were put in place to prevent corporations from simply packing up and moving to whichever country is the most economically depressed and hence has the cheapest work force. The end result will be loss of jobs in the USA, and no real help to the Bolivian people, since the profits will go to those Bolivians which are already extremely rich. Beside this, President Smith's wife, who accompanied him on his diplomatic mission to Bolivia to sign the treaty, refused to eat "cuy" which is a national dish of Bolivia, offending all Bolivians present at the treaty signing ceremony. Hence not only does President Smith not care about his own fellow Americans, he has a wife who is so insensitive to the Bolivian people that she insulted all of them needlessly. Clearly President Smith's decision to sign the treaty with Bolivia is wrong.

Observe the above argument gives some reasons why the given treaty would be a bad idea, but also commits the ad hominem fallacy by attacking President Smith's wife. The correct way to analyze this argument is to point out the premises whose truth does affect the conclusion such as jobs being lost in the USA, economic benefits not going to the average Bolivian etc., and point out that the comment about President Smith's wife is an ad hominem attack and is irrelevant to the truth of the conclusion.

Since it is impossible to point out logical fallacies if you are unable to identify them, I list below just a few common logical fallacies and give a link at the end where many more are given. It is helpful to become familiar with as many as possible.


Some Common Logical Fallacies

Common Name

Defining Characteristics

Post hoc (ergo propter hoc)

Since y follows x, then x is the cause of y

Hasty generalization / bad induction

Takes a small set of examples and assumes all other examples are the same

Appeal to (inappropriate) authority

Appeals to the opinions of someone who is not an expert in the given field under debate

False dilemma/all or nothing/black-white

Presents two choices (many times extreme) as if they were the only ones, when there are others

Argument from ignorance

Assumes x is false since it has not been proven true, or that x is true, since x has not been shown to be false (hint: this fallacy is committed in the counter argument on page 2, can you find it?)

Slippery slope


A series of consequences which lead to an undesirable conclusion are said to follow from an a particular claim which casts doubt on the truth of the claim. What makes this chain of reasoning a fallacy is that each consequence is thought to be unlikely.


ad hominem (abusive)


Casting doubt or arguing against a specific claim by attacking some personal aspect of the person making the claim. Attacking the person making the argument rather than the argument.

ad hominem (circumstantial)


Same as above except one attacks the circumstances of the individual rather than the argument where circumstances might be; where one lives, one's nationality, where one works, one's marital status etc.


Begging the question/ circular reasoning


This occurs when the truth of the conclusion is already contained in one or more premises. In other words this fallacy occurs when a person assumes the very thing they are supposed to prove.


This fallacy occurs when one characterizes another argument in such a way as to make it patently absurd or much easier to argue against. This fallacy is very common and also difficult to detect since its detection requires knowledge of the proper characterization of the original claim.


inability to be falsified


This occurs when a proposition (not claimed as an axiom) is such that nothing could show it to be false. In other words, normal propositions about the world have consequences if true, a proposition which has no such consequences is said to be unfalsifiable, hence to assert that it might be false is an error in reasoning.


Appeal to tradition

This fallacy occurs when the truth of a claim is said to follow from traditional views or claims like "that is the way it has always been . . .".

ad populum / appeal to the masses

This fallacy occurs when the truth of a claim is stated to follow from the mere fact that everyone believes it to be true or, equivalently, no one doubts it.


The above list is quite short. There are dozens of such fallacies. Thankfully there are several great online sites which list many more together with examples.

See the sidebar Learn more for links.



Value: 10

Match the items.

The task is to match the lettered items with the correct numbered items. Appearing below is a list of lettered items. Following that is a list of numbered items. Each numbered item is followed by a drop-down. Select the letter in the drop down that best matches the numbered item with the lettered alternatives.

a. ad hominem circumstantial

b. strawman

c. Post hoc

d. slippery slope

e. ad hominem abusive

f. Hasty Generalization

g. appeal to inappropriate authority

h. False dilemma

i. begging the question / circular reasoning

j. Argument from ignorance