The illicit major fallacy occurs when a quality or feature mentioned in the premise about only some members of a group is incorrectly applied to the entire group in the conclusion.
Definition:
This fallacy arises when the major term [1] in the premises applies only to part of a group, but is then unjustifiably extended to the whole group in the conclusion. In such cases, the conclusion goes beyond the scope of the premises, rendering the syllogism invalid because it makes an unwarranted leap from part to whole. This is what is called the illicit major fallacy. For example:
”Some animals can fly. [Major premise]
All cats are animals. [Minor premise]
Therefore, all cats can fly. [Conclusion]”
Here, it should be noted that “being able to fly” is the major term, which in the premise refers only to some animals, but in the conclusion is incorrectly applied to all cats. This is a clear example of an invalid syllogism resulting from the illicit extension of the major term.
Now that we have seen how this type of reasoning becomes invalid, and will encounter further examples below, it is helpful first to understand what a valid syllogism looks like—something the illicit major fallacy fails to achieve.
In a valid syllogism, the scope of the conclusion must not exceed that of the premises. If a characteristic is mentioned only in relation to a whole or a part of a group, it cannot be applied to an entirely different group in the conclusion. For example:
”All humans are mortal. [Major premise]
All philosophers are human. [Minor premise]
Therefore, all philosophers are mortal. [Conclusion]”
Here, it should be noted that “being mortal” is the major term, which is stated for all in the first premise and remains so in the conclusion. Moreover, the subjects, “humans” and “philosophers”, are used precisely, without any unjustified extension. Thus, this is a valid syllogism.
Typical structure of this fallacy:
- Major premise: Some M are (or are not) P.
- Minor premise: All S are M.
- Conclusion: Therefore, all S are (or are not) P.
Here, the major term “P” refers only to a part of its category in the premise but is illegitimately applied to all of it in the conclusion. For example:
“Some fruits are sweet. [Major premise]
All lemons are fruits. [Minor premise]
Therefore, all lemons are sweet. [Conclusion]”
Here, it should be noted that the major term “being sweet” refers only to some fruits in the premise, but in the conclusion it is wrongly applied to all lemons. This is a case of the illicit major fallacy, which makes the syllogism invalid.
Examples from real life:
1. In politics:
a) ”Some members of Party A are authoritarian. [Major premise]
No member of Party B is in Party A. [Minor premise]
Therefore, no member of Party B is authoritarian. [Conclusion]”
Here, it should be noted that the major term, “being authoritarian”, refers only to some members of Party A in the major premise, but is wrongly applied to all members of Party B in the conclusion. This kind of reasoning can be misused to discredit one party and absolve another.
b) ”Some members of parliament are dishonest. [Major premise]
No government minister is a member of parliament. [Minor premise]
Therefore, no minister is dishonest. [Conclusion]”
Here, it should be noted that the major term, “being dishonest”, refers only to some members of parliament in the major premise, but is wrongly applied to all ministers in the conclusion, implying that all ministers are honest. This is a case of illicit major, and such reasoning can be used to mislead public opinion.
c) ”Some luxury goods are expensive. [Major premise]
No fresh bread is a luxury good. [Minor premise]
Therefore, no fresh bread is expensive. [Conclusion]”
Here, it should be noted that the major term, “being expensive”, refers only to some luxury goods in the major premise, but in the conclusion, it is unjustifiably applied to all fresh bread. This fallacy may be used to deceive the public—for example, an incompetent politician might compare bread to luxury items to suggest that bread is cheap, while in reality, their poor policies have made bread and other essentials more expensive.
2. In education:
a) ”Some children who attend music classes are creative. [Major premise]
None of the neighbour’s children attend music classes. [Minor premise]
Therefore, none of the neighbour’s children are creative. [Conclusion]”
Here, it should be noted that the major term, “being creative”, refers only to some children who attend music classes, but in the conclusion it is unjustifiably applied to all the neighbours’ children. This is a faulty leap from the particular to the general, which undermines the validity of the argument.
b) ”Some students in the mathematics stream are clever. [Major premise]
No student in the arts stream studies mathematics. [Minor premise]
Therefore, no student in the arts stream is clever. [Conclusion]”
Here, it should be noted that the major term, “being clever”, refers only to some mathematics students in the premise, but in the conclusion it is unjustifiably denied to all arts students. This kind of reasoning can lead to discrimination and stereotyping within education, whereas talent and ability are not confined to any particular field of study.
3. In consumer economics:
a) ”Some salads are fatty. [Major premise]
No fast food is a salad. [Minor premise]
Therefore, no fast food is fatty. [Conclusion]”
Here, it should be noted that the major term, “being fatty”, refers only to some salads in the premise, but in the conclusion it is unjustifiably denied to all fast foods. This kind of reasoning may be exploited in advertising to falsely suggest that fast foods are harmless.
b) “Some branded clothes are of high quality. [Major premise]
No second-hand clothes are branded. [Minor premise]
Therefore, no second-hand clothes are of high quality. [Conclusion]”
Here, it should be noted that the major term, “high quality”, refers only to some branded clothes in the major premise, but in the conclusion it is unjustifiably applied to all second-hand clothes. This is the illicit major fallacy, which is often used in fashion advertising to devalue the purchase of second-hand clothing.
c) “Some expensive creams are effective. [Major premise]
No pharmacy creams are expensive. [Minor premise]
Therefore, no pharmacy creams are effective. [Conclusion]”
Here, it should be noted that the major term, “effective”, refers only to some expensive creams in the major premise, but in the conclusion this quality is unjustifiably denied to all pharmacy creams. This is a typical advertising tactic used by cosmetic companies to persuade people to buy more expensive products.
d) “Some types of sugar are beneficial for the body. [Major premise]
Soft drinks and processed foods contain sugar. [Minor premise]
Therefore, soft drinks and processed foods are beneficial for the body. [Conclusion]”
Here, it should be noted that the major term, “being beneficial for the body”, refers only to certain types of sugar in the major premise, but in the conclusion it is wrongly extended to all sugary processed products. This is a clear example of the illicit major fallacy, rendering the reasoning invalid. Greedy food industries exploit this fallacy by using the body’s natural need for sugar as a marketing tool, suggesting that any sugary processed product is “necessary”, even though added sugars are a major cause of obesity, diabetes, and heart disease.
4. In everyday life:
a) “Some scientific books are interesting.” [Major Premise]
“No romantic novel is a scientific book.” [Minor Premise]
“Therefore, no romantic novel is interesting.” [Conclusion]
Here, it should be noted that the major term, “being interesting”, refers only to some scientific books in the major premise, but in the conclusion it is wrongly extended to all romantic novels. This is the fallacy of the illicit major, which may be used to discredit an entire literary genre and dismiss its value.
b) “Some taxi drivers are polite.” [Major Premise]
“No motorcyclist is a taxi driver.” [Minor Premise]
“Therefore, no motorcyclist is polite.” [Conclusion]
Here, it should be noted that the major term, “being polite”, refers only to some taxi drivers in the major premise, but in the conclusion it is wrongly extended to all motorcyclists. This is the fallacy of the illicit major, which can lead to the formation of negative stereotypes and misguided assumptions in everyday conversations.
c) “Some fresh fruits are sweet.” [Major Premise]
“No frozen fruit is fresh.” [Minor Premise]
“Therefore, no frozen fruit is sweet.” [Conclusion]
Here, it should be noted that the major term, “being sweet”, refers only to some fresh fruits in the major premise, but in the conclusion it is wrongly extended to all frozen fruits. This is the fallacy of the illicit major, which renders the argument invalid and may lead to the formation of false beliefs in everyday life.
Why is this fallacy dangerous?
- Unjustified generalisation: A quality that applies only to some of a group in the premises is wrongly extended to the whole group in the conclusion.
- Logical appearance: The argument has a seemingly logical form, which gives it the appearance of validity and can therefore mislead the audience.
- A tool for political and advertising manipulation: This fallacy can be used in politics and advertising to justify discrimination or even human rights violations, as it presents a false conclusion in a form that appears logically sound.
How can we recognise it and respond?
Look at the conclusion and ask:
– Has the conclusion extended beyond the scope of the premises?
– Has the major term been used in the same general sense in the premises, or only applied to a part of the group?
A suitable response might be: “In this argument, you have attributed a feature to the whole group, whereas in the premises it was only applied to a part of it.”
Conclusion:
This fallacy reminds us that a logical conclusion must be based strictly on what is stated in the premises. If the premises refer only to part of a group, applying the conclusion to the whole group is both incorrect and misleading.
Recognising this logical error helps protect us from linguistic and advertising deception, and ensures that concepts like “law”, “democracy”, or “human rights” are used in their true and proper sense, not in a distorted or manipulative way [2].
[1] The major term refers to a quality, characteristic, or concept that appears in the major premise as the conclusion-bearing element and is repeated in the conclusion. For example:
“Some sugars are beneficial for the body. [Major premise]
Soft drinks and processed foods contain sugar. [Minor premise]
Therefore, soft drinks and processed foods are beneficial for the body. [Conclusion]”
Here, it should be noted that the major term, “being beneficial”, refers only to some sugars in the premise, but in the conclusion it is wrongly applied to all processed products.
[2] Studying the illicit major fallacy reveals that many reasoning errors stem from improper generalisation and the unwarranted extension of attributes, qualities, or concepts. True philosophy, unlike academic philosophy, insists that no partial characteristic should be generalised to an entire group. This precision helps prevent political and promotional misuse—just as the accurate definition of concepts like “law” and their clear distinction from “non-law” lays the groundwork for protecting human rights and resisting linguistic or political manipulation.