A non sequitur error is a statement or conclusion which does not follow logically from what preceded it. Non-sequiturs can be responses that have nothing to do with the conversation or incorrect conclusions “based” on what preceded them. Non-logical fallacy is also known as irrelevant reason, derailment and invalid inference.
Cause
A non sequitur is any argument that does not follow from the preceding statements. The expression “non sequitur” means “it does not follow” in Latin. Although the term was originally used in the context of philosophy to refer to bad logic, today it is used more broadly for any type of statement that seems to come out of nowhere.
A non-sequitur is a formal logical error because the error lies in the structure of the argument. More specifically, there is a logical gap between the premise or evidence provided and the conclusion drawn from it. Even if everything is verified and true, the logic between each element is not present.
A non sequitur argument is characterized by reasoning or evidence that is completely unrelated to the claim being made. Non-sequences have the following characteristics:
- These are declarations which do not provide any information in relation to the question or to the previous declaration.
- These are not just random statements. Rather, they are responses to something that preceded them. If you walked up to a stranger and said “polar bears can reach speeds of up to 6 mph in water,” that would be random (or even a little scary). But if a friend asked you how you were and you responded with something about polar bears, that would be nonsense.
- They are often absurd or surreal and can be used to add a touch of humor.
- Non-sequiturs often contain words like "therefore" and "therefore," but the context of the statement may also suggest that it is a conclusion.
Examples
Non-sequential errors are obvious when they are absurd, but they can sometimes go unnoticed because the logical jump can be harder to spot.
“Investing in cryptocurrencies is a risk, but everything in life has a risk. Every time you drive a car, you take a risk. If you are willing to drive a car, you should be willing to invest in cryptocurrencies.
“I heard about a snake attack in the newspapers. My friend has a pet snake. My life must be in danger.
“When the weather is nice, I see my neighbor walking his dog. He should only walk the dog when the sun is out.
How to avoid non sequitur errors?
Repeat your thesis and hypotheses at the beginning of the paragraph. In order to check the logical sequence of your speech, you can replace each element with a letter and to write the resulting equation.
EN 
FR