Welcome to the #FallacyFridays! Every Friday, we put the spotlight on a logical fallacy, a flawed way of reasoning. Today’s logical fallacy is called denying the antecedent. Continue below to learn all about it. 🤓

Now before we get into the denying the antecedent fallacy, let’s do a quick throwback. If you were here last week, you learned about the affirming the consequent fallacy. 

And if you compare the names of last week’s fallacy with this week’s, you might notice somewhat of a relationship between them.

“Affirming” (from the “affirming the consequent” fallacy) and “denying” (from the “denying the antecedent” fallacy) are opposites. Likewise, so are “consequent” and “antecedent.”

Last week’s fallacy (the “affirming the consequent” fallacy) followed the syllogism (or pattern):

If A, then B.

It’s B. Therefore, A.

Today’s fallacy (the “denying the antecedent” fallacy) follows the syllogism:

If A, then B.

It’s not A. Therefore, it’s not B. 

Now let’s look at some examples of the denying the antecedent fallacy for a little bit of clarity. 😁

Example #1 of the Denying the Antecedent fallacy:

Let’s say that you found yourself deep in your feelings. And, for some odd reason, you conclude the following: “If my love interest looks me in the eye when I talk to them, then they like me. They didn’t look me in the eyes. Therefore, they don’t like me. 😭”

Now this is the part where I’d come up to you like, “Dude, do you know there is such a thing as being shy or reserved? Just because they didn’t look you in the eye doesn’t mean they don’t like you!” 

And hopefully, you’d catch the flaw in your logic.

Example #2 of the fallacy:

“If the train arrives on Track A, then it is northbound. The train did not arrive on Track A. Therefore, it’s not northbound.”

But it’s possible for a train to be northbound on other tracks, right? Right.

You might be noticing why the denying the antecedent fallacy is a flawed way of reasoning: it assumes that the opposite of the first scenario is necessarily true. But that isn’t always the case.

In the first example, it’s possible that your love interest has another reasons for not looking you in the eye that do not have anything to do with a lack of romantic feelings towards you.

It’s also possible for a train to be northbound on a track other than Track A.

Pro-Tip: Check your bias by seeing if there are other possibilities beyond the opposite of the first statement, “If A, then B.”

Quiz time!

I’m going to give you four answer choices. Which answer choice contains the denying the antecedent fallacy?

A. If you walk home at night, you’ll likely get attacked. You didn’t get attacked, so you likely did not walk home at night.

B. If you stayed home, you wouldn’t have been so bored. Next time, come with us to see Ariana perform. You love her music. 

C. If you try the Redfire brand of hot sauce, you’ll love it. You loved the one you ate last night, so it must have been the Redfire brand.

D. I just sent you an email. If you responded, that means you’ve seen it. You didn’t respond, so that means you haven’t seen it.

Wanna see if your answer choice was correct? Want the explanation behind the correct answer choice? Get FREE access to the Fallacy Fridays Answer Key and be notified of all future Fallacy Fridays posts, quizzes, and answer explanations!