SOYOUWANNA AVOID THE LOGIC ERROR OF USING NON SEQUITURS?

When people speak about a logical argument, they are referring to a premise or series of premises that is or are intended to lead to a conclusion. A non sequitur is when such good intentions fail. "Non sequitur" is Latin for "it does not follow." To say that an argument is a non sequitur is simply to say that the conclusion does not follow from the premises. This term would apply to any argument that has a conclusion that doesn't follow from its premises. It is often used, however, to refer to particular types of arguments that clearly do not follow from their premises and never could.

For example, any argument that takes the following form is a non sequitur:

Step 1: If A then B If I am a goat, I am a hoofed creature. Step 2: B I am a hoofed creature. Step 3: Therefore, A Therefore, I am a goat.

It is clear that this argument does not follow. Even if the premises and conclusion were all true, the conclusion is not a necessary consequence of the premises. This sort of non sequitur is also called "affirming the consequent."

Another common non sequitur is this:

Step 1: If A then B If A then B If I am in Rome, I am in Italy. Step 2: Not A If I am in Rome, I am in Italy. Step 3: Therefore, not B Therefore, I am not in Italy.

The speaker could be in all kinds of other places in Italy, worrying way less about pickpockets and having a great time. This sort of non sequitur is called "denying the antecedent."

SoYouWanna know more? Check out our full-length article SYW avoid common logical errors?