What’s going on when the reasons we give to support or refute a statement have no relation to it at all? What is the fundamental error of reasoning underpinning almost all logical fallacies, and when does this represent special cases?
Here we discuss the general fallacy of the Non Sequitur, Latin for does not follow.
This can generally refer to any sort of logical fallacy, any argument where a logical connection between premises is implied that just isn’t there.
This fallacy is often found with other forms of invalid reasoning in the very same statement. Here’s a couple of handy examples of the most common form:
Our cult shall be feared by all, for Azathoth is freakin’ scary when annoyed.
Human-caused global warming is impossible, because it’s cyclical, the ozone hole over the antarctic is closing, cow farts, and Mars is warming too, not just the earth.
But there are more specific named forms of this fallacy as well:
The Fallacy of the Undistributed Middle:
In which a conclusion is incorrectly drawn from two given or assumed premises, and takes the form of:
All Xs are Cs.
A is a C.
So, A is an X.
An obviously ridiculous example would be:
All birds generate their own body heat.
My cats generate their own body heat.
My cats are birds.
…Denying the Antecedent:
Which takes the form of:
If C is true, then D is true.
C is false.
So, D is also false.
A good example would be:
If I am in ancient Athens, I’m in Greece.
I’m not in ancient Athens.
So, I’m not in Greece.
This is absurd, as there are many locations and times in Greece other than Athens or the Ancient period. There is also…
…Affirming the Consequent:
which takes the form:
If C is true then D is true.
D is true.
So C is true.
If my Senior Technician intends to transfer me to another project, she’ll have a talk with the Program Director.
My Senior Technician is going to talk with the Program Director.
She wants to get me transferred to another project.
This last is clearly an example of invalid reasoning because the Senior Tech could be seeing the Program Director for entirely different reasons than those given.
One problem people sometimes have with this fallacy is that it can be subtle, and they are often too proud to speak out when they cannot see how an argument follows, or are too polite to point out its lack of relevance to the speaker.
It’s important to more specifically pick out what is being said even as a less general sort of fallacy, including the non sequitur’s aforementioned variants.
So be careful that what facts you bring to an argument are actually relevant to the point you’re trying to make. Otherwise, it may just fail the application of the “so what” test!
Tf. Tk. Tts.
(Fully Updated, Retitled, Broken Links Removed on 2017.06.06)