This fallacy occurs when the conclusion of an argument lacks any logical connection to its premises. Consequently, even if the premises are true, the conclusion does not necessarily follow from them.
Definition:
The Non Sequitur (Formal) Fallacy[1] is a formal error in logic whereby the conclusion of an argument is not, structurally, a consequence of its premises. Unlike specific fallacies such as “Affirming the Consequent” or the “Undistributed Middle,” this fallacy refers to any argument that appears syllogistic but whose conclusion lacks a logical connection to its premises. Put simply, the arguer seeks to prove something that the premises cannot establish. For example:
“This film has won an Oscar. Therefore, watching it will certainly make you happy.”
Here, it should be noted that a film winning an award at a festival bears no logical connection to the degree of happiness or satisfaction it may bring to an individual viewer.
The typical structure of this fallacy:
- A is true.
- B is true.
- Therefore, X is true.
(While X follows logically from neither A nor B.)
Examples from real life:
1. In science:
“All the planets in the solar system revolve around the sun. The Earth is also a planet. Therefore, life is possible only on Earth.”
Here, it should be noted that the premises are true, but the conclusion has no logical connection to them.
2. In politics:
“This politician is very honest. Therefore, he must be the next president.”
Here, it should be noted that honesty is a virtue, but it does not provide a logical basis for presidential competence.
3. In economics and business:
“This company made a large profit last year. Therefore, its CEO is an ethical person.”
Here, it should be noted that financial profit has no direct connection to ethical conduct.
4. In everyday life:
“I love Italian food. So I must travel to Spain for my holiday.”
Here, it should be noted that a liking for food has no logical connection to the choice of a travel destination.
5. In advertising:
“Drink this beverage and you will become popular among your friends.”
Here, it should be noted that consuming a drink provides no logical reason for social popularity.
Why is this fallacy dangerous?
- It creates the illusion of logic: a chain of seemingly coherent statements is presented, but in reality, no connection exists between them.
- It serves as a tool of deception in politics and advertising: by ignoring the logical gap, people are led to accept desired conclusions.
- It conditions the mind: we become accustomed to accepting false connections, and our capacity for critical thinking is weakened.
How can we recognise and respond to it?
If the conclusion has no real connection to the premises, ask:
– “Is the proposed conclusion truly a logical consequence of these premises?”
– “Could the premises be true while the conclusion is irrelevant or false?”
– “Is the conclusion stated merely on the basis of association or emotions?”
A suitable response might be: “Your premises may be true, but the conclusion lacks any logical connection to them. Your argument is flawed by the Non Sequitur Fallacy and requires independent justification.”
Conclusion:
The Non Sequitur (Formal) Fallacy is one of the most fundamental yet prevalent logical errors. It underscores that the mere truth of the premises is insufficient for an argument’s validity; what matters is the logical connection between premises and conclusion. Recognising this fallacy enables us to identify arguments that are deceptive yet invalid, and to accept only those conclusions that truly follow from the premises.
[1] The term “Formal” is used to distinguish this fallacy from its informal applications. Non Sequitur, in its broader sense, refers to any irrelevant conclusion, even in humorous remarks or everyday conversation. Here, however, it denotes a formal error in the structure of reasoning, where the conclusion does not logically follow from the premises.