When both initial premises say only “no”, no valid conclusion can be drawn, yet a conclusion is still attempted.
Definition:
The exclusive premises fallacy occurs when, in a syllogistic argument, both premises are expressed negatively. That is, both state only what something is not, without showing what it is. Here, it should be noted that if neither premise establishes an affirmative (positive) connection between the concepts, the argument cannot yield a valid conclusion. For example:
”No doctor is a teacher. [Major premise]
No teacher is an engineer. [Minor premise]
Therefore, no doctor is an engineer. [Conclusion]”
Here, it should be noted that both premises are purely negative and establish no affirmative link between “doctor” and “being an engineer”. Therefore, the conclusion is not logically valid, even though it may appear orderly.
Typical structure of this fallacy:
- Major premise: No M is P.
- Minor premise: No S is M.
- Invalid conclusion: Therefore, no S is P.
“M”, as the middle term, makes no positive connection with either “S” or “P”. Therefore, it cannot link them.
Examples from real life:
1. Politics and human rights:
a) ”No freedom-lover is oppressive. [Major premise]
No dictator is a freedom-lover. [Minor premise]
Therefore, no dictator is oppressive. [Conclusion]”
Here, it should be noted that both premises are expressed negatively, and neither establishes an affirmative link between “dictators” and “being oppressive”. Drawing a conclusion from such premises is logically invalid. This type of fallacy can be used in politics to exonerate dictators or distort human rights concepts, creating a seemingly logical cover that prevents reality from being examined and paves the way for a reversal of the truth.
b) ”No army that is a peacekeeping force kills civilians. [Major premise]
No member of our military alliance is a hostile army. [Minor premise]
Therefore, no member of our alliance kills civilians. [Conclusion]”
Here, it should be noted that this argument is formed from two negative premises and cannot support such a conclusion. No direct connection is established between being a member of the alliance and “not killing civilians”. This fallacy is very common in media coverage of wars, where the crimes of allies or one’s own forces are overlooked because they are not labelled “hostile” and are given the title of “peacekeepers”.
c) ”No human rights defender supports censorship. [Major premise]
No dictator is a human rights defender. [Minor premise]
Therefore, no dictator supports censorship. [Conclusion]”
Here, it should be noted that both premises are negative, and therefore no valid conclusion can be drawn from them. No positive connection is established between “dictator” and “censorship”. This type of reasoning can be used in deceptive political or media discourse, where attempts are made to present authoritarian regimes in a humanised light. In reality, however, the opposite is true: many repressive regimes both violate human rights and are the main agents of censorship.
2. Consumer economics:
a) ”No natural supplement is artificial. [Major premise]
No product of company Z is a natural supplement. [Minor premise]
Therefore, no product of company Z is artificial. [Conclusion]”
Here, it should be noted that both premises are negative and establish no affirmative link between “the products of company Z” and “being artificial”. The conclusion that “no product of company Z is artificial” is invalid because it is built only on two negations and creates no valid relationship between the premises. Such reasoning can be used in consumer advertising, where a company highlights misleading labels such as “natural” or “free from artificial additives” to make all of its products appear healthy or non-artificial, while the reality may be quite different.
b) ”No luxury item is cheap. [Major premise]
No product in this shop is a luxury item. [Minor premise]
Therefore, no product in this shop is cheap. [Conclusion]”
Here, it should be noted that both premises are negative and establish no affirmative link between “the products of this shop” and “being cheap”. The conclusion that “no product in this shop is cheap” is invalid because it is based only on two negations. Such reasoning can be used in commercial rivalry or negative advertising, where competitors exploit the seemingly logical form of the argument to create a false image of a shop’s prices or product quality and mislead customers.
3. Everyday life:
a) ”No maths class is a PE class. [Major premise]
No art class is a maths class. [Minor premise]
Therefore, no art class is a PE class. [Conclusion]”
Here, it should be noted that both premises are negative and establish no positive link between “art class” and “PE class”. Therefore, the conclusion is invalid, even though the sentence may appear logical at first glance.
b) ”No vegetarian eats meat. [Major premise]
None of my colleagues is a vegetarian. [Minor premise]
Therefore, none of my colleagues eats meat. [Conclusion]”
Here, it should be noted that both premises are stated negatively and establish no positive link between “my colleagues” and “eating meat”. Thus, the conclusion is invalid. This type of reasoning is very common in everyday conversations, where a false conclusion is drawn from two negatives. Its seemingly logical form may deceive the listener, while in fact it has no argumentative basis. In reality, my colleagues may or may not eat meat; these premises do nothing to clarify the matter.
Why is this fallacy dangerous?
- It has a logical appearance, but in practice it establishes no valid connection.
- In politics, media, and advertising it can be used to distort reality and mislead the public.
- From a psychological point of view, the combination of two negatives may give an impression of certainty, but from a logical perspective it has no sound basis.
How can we recognise it and respond?
“In a syllogism, the ‘middle term’ is the concept that appears in both premises and acts like a bridge linking the major term and the minor term. If this bridge is not established, the syllogism will be invalid. If both premises are negative (‘no … is’ / ‘none … are’), sound the alarm and ask:
– Does the middle term (M) appear affirmatively in one of the premises to connect with either side?”
A suitable response might be: “In this argument, both premises are negative and no positive link is established between them. From such premises, no valid conclusion can be drawn.”
Conclusion:
It should be noted here that a syllogism is valid only when the middle term can link the two sides of the argument. When both premises are purely negative, this connection is absent. The exclusive premises fallacy shows us that what may seem “sound” on the surface can, in fact, lack any valid foundation. Recognising this error makes us more resistant to many linguistic tricks and logical deceptions in society.