Examples of non sequitur fallacies, also known as formal fallacies, aren’t easy to find in daily life because they typically occur in formal disciplines such as logic, mathematics, and physics. The following example illustrates the nature of a non sequitur fallacy:
Premise: All cats are mammals.
Premise: A dog is a mammal.
Conclusion: Therefore, a dog is a cat.
More specifically, this example falls into the subcategory of the fallacy of the undistributed middle, in which the middle term in the premises doesn’t cover all possible cases, leading to a faulty conclusion.