A photograph of several students studying together in a library. There are two females and two males present.

Source: Study Group at UBC Library, UBC Library, Flickr

Consider the following argument:

If the professor doesn’t give us extra study time for the exam, we’ll fail the test and then fail out of school. We won’t get jobs, and we’ll wind up homeless. And the terrorists will have won!

Are you convinced by these claims? They seem rather absurd, don’t they? The writer has created a kind of logical fallacy that we call a slippery slope.

The student claims that a chain reaction ending in a dire consequence will occur if we take even one step on this slippery slope, assuming that there’s no stop partway down the hill between lack of study time and the triumph of terrorism. As you can see, the reasoning is simply not logical.

Recognizing logical fallacies in others’ arguments, as well as spotting them in your own writing, is an important skill to master. In this section of the lesson, you will learn to name some of the most common fallacies, such as slippery slope, and identify them in argumentative claims.

As you read the chart below, keep in mind that rhetorical fallacies often overlap.

Type of Fallacy Definition Examples
Ad hominem (from the Latin for “against the person”) A personal attack on the character of one’s opponent, designed to distract the reader from the opponent’s argument The strategies of Green Peace (an environmental organization) aren’t effective because the members of the organization are all dirty, lazy hippies.
Hasty generalization A conclusion based on insufficient evidence (rushing to the conclusion before you have all the facts)

Red flags that often indicate a hasty generalization include absolute words such as all, ever, always, never, instead of; and qualifiers such as most, many, usually, seldom. Hasty generalizations often involve stereotyping.
• Even though it’s only the first day, I can tell this is going to be a boring course.

• Most politicians are corrupt.
Slippery slope An argument based on the premise that if A happens, then eventually through a series of small steps B, C, D . . . X, Y, Z will happen, too, basically equating A and Z. So if we don’t want Z to occur, we must not allow A to occur. If we ban Hummers because they are bad for the environment, eventually the government will ban all cars.

(Think of “Hummers” as A and “all cars” as Z on this slippery slope.)
Non sequitur (from the Latin for “it does not follow”) A conclusion that cannot be logically drawn from the premises Stanley is tall. Therefore, he will be an excellent basketball player.
Bandwagon An argument based on the assumption that the opinion of the majority is valid; might also be called “an appeal to a commonly held opinion”

The expression “jumping on the bandwagon” means doing or thinking something just because everyone else does.
• Since everyone prefers vanilla ice cream, you should, too.

• During ancient times, many people believed the earth was flat, so the earth must have been flat during those times.
Circular argument A restatement of a claim offered as evidence of its validity
Taylor Swift is a good singer because she sings well.
False dilemma An argument in which two choices are presented as the only options available; might also be called the “either-or” fallacy Either the camper saw a ghost, or he’s a liar.
A Super Man comic that has a non sequitur in the dialogue.

Source: The Silver-Age Lois Lane had Issues, Odd Issues, Terry McCombs, Flickr

In many ways, all logical fallacies are non sequiturs. The reasoning “does not follow” because some necessary part of the logical sequence has been left out.

Now, try your hand at identifying the different types of logical fallacies.

icon for an interactive exercise

Fallacies weaken arguments. Look out for them in the arguments of others and avoid them in your own arguments. Non sequitur is a good way to summarize logical fallacies. If the reasoning “does not follow,” don’t be swayed by it in someone else’s argument or include it in your own.