Semantic Fallacies: Defects of Matter, Form, and Predication

1. A new stage: fallacies arising from meaning

In verbal fallacies, ambiguity in an expression or its construction undermined an argument. In semantic fallacies, the expressions can be intelligible while the relation between premises, or the way a conclusion is drawn from them, remains defective.

فصل في الأغاليط التي تقع بسبب المعنى
A section on fallacies that arise from meaning.

The key question is where an inference fails: in the truth of what it presupposes, or in the logical connection that ought to produce its conclusion. This is the distinction between matter (mādda) and form (ṣūra).

2. Matter and form answer different questions

إما من جهة المادة أو من جهة الصورة
These errors arise either from matter or from form.

A defect of matter concerns the truth or reliability of a premise. A defect of form concerns entailment: even if both premises are granted, does the conclusion have to follow?

Example 1: “Every bird is a fish; every fish is an animal; therefore every bird is an animal.” The pattern can be valid while the first premise is false.
Example 2: “Every pigeon is a bird; every sparrow is a bird; therefore every pigeon is a sparrow.” Both premises can be true while the conclusion fails to follow.

3. A special material defect in the textbook

A distinctive material fallacy arises when the meanings, read in one way, yield true statements but not a well-formed syllogism. Rearranging the same expressions into syllogistic form then makes a premise false.

إذا رتب المعاني فيه على وجه يكون صادقاً لم يكن قياساً
When the meanings are arranged in a truthful way, they do not form a syllogism.

The problem is not merely that a false premise leads to an error. It is the mistaken attempt to obtain both true premises and a shared middle term by quietly changing how a qualification is understood.

4. The text’s example: the qualified term “rational”

الإنسان ناطق من حيث هو ناطق، ولا شيء من الناطق من حيث هو ناطق بحيوان
The human is rational insofar as rational, and nothing rational considered only in that respect is an animal.

The first statement predicates rationality of humans. The second abstracts “rational insofar as rational,” considering that characteristic without animality as part of its concept. Treating these two standpoints as an identical middle term is the source of the confusion.

Here nāṭiq is the classical logical differentia of the human, not merely the capacity to utter spoken words.

5. Why the alleged conclusion is unacceptable

فلا شيء من الإنسان بحيوان
Therefore, no human is an animal.

That is the purported conclusion, but it is unacceptable. The qualification on “rational” shifts the respect under which the middle term is considered. A word can look the same while failing to serve as one logically identical middle term throughout the proof.

Classical classification holds that every human is an animal. Examining rationality as an abstract differentia does not abolish this generic relation. The mistake confuses a conceptual abstraction with a judgment about the complete subject.

6. A sound syllogism keeps its middle term fixed

Contrast the fallacy with a valid first-figure syllogism:
كل إنسان ناطق
Every human is rational.
كل ناطق حيوان
Every rational being is an animal.
فكل إنسان حيوان
Therefore every human is an animal.

The middle term, rational, is used with the same logical force in both premises. The minor is affirmative, the major universal, and the first-figure requirements are satisfied.

Adding or removing a qualification is therefore not a harmless verbal change. It may change the premise and the inference itself.

7. Formal error: an unproductive arrangement

وأما التي من جهة الصورة فكلها يكون على هيئة غير منتجة
As for errors of form, all occur in an arrangement that does not produce a conclusion.

A productive syllogism must connect its minor and major terms by a properly functioning middle term. Two meaningful and true premises alone are insufficient.

When the conditions of production are violated, the stated conclusion might accidentally be true. It is nevertheless not established by those premises. That is the essential mark of a formal fallacy.

8. The text’s example: time and the celestial sphere

الزمان محيط بالحوادث، والفلك محيط بها أيضاً
Time encompasses events, and the celestial sphere also encompasses them.

The alleged conclusion is فالزمان هو الفلك
Therefore time is the celestial sphere.

“Encompassing events” is predicated of both subjects. This resembles figure two, but both premises are affirmative. Figure two requires a difference in quality between its premises. Sharing a predicate cannot establish identity between the subjects.

The celestial-sphere example belongs to classical cosmological discourse; it should not be presented as a confirmed modern physical model.

9. Sharing a predicate does not prove identity

كل قط حيوان
Every cat is an animal.
كل كلب حيوان
Every dog is an animal.

These do not entail that every cat is a dog. Cats and dogs belong to a wider genus without being the same species.

This simpler example exposes the flaw in the time-and-sphere argument. Two affirmative premises sharing a predicate do not yield identity. When the middle term is the predicate of both premises, the productive conditions of figure two must be observed.

10. Why figure two requires opposite qualities

A productive second-figure example is:
كل إنسان حيوان
Every human is an animal.
لا شيء من الحجر بحيوان
No stone is an animal.
فلا شيء من الإنسان بحجر
Therefore no human is a stone.

The middle term animal is affirmed of one subject and denied of the other. This difference in quality provides the exclusion required for a negative conclusion.

By contrast, two affirmatives can describe different subjects sharing an attribute, without establishing any identity between them.

11. Recognizing begging the question

من المغالطات الصورية المصادرة على المطلوب
Among the formal fallacies is assuming the very point at issue.

Muṣādara ʿalā al-maṭlūb (begging the question) occurs when the proposition to be established, or an equivalent claim, is already smuggled into a premise. The conclusion then merely repeats what was assumed.

The inference may even resemble a valid pattern, but it supplies no independent ground for the disputed claim. A demonstrated conclusion is different from a renamed assumption.

12. Zayd, bashar, and insān in the source

زيد إنسان؛ لأنه بشر، وكل بشر إنسان
Zayd is human because he is a bashar, and every bashar is human.

In this setting, bashar and insān effectively convey the same human nature. If the question is precisely whether Zayd is human, merely assuming he is bashar, without independently establishing that premise, restates the disputed point.

The issue is not simply that two words are synonyms. The critical question is whether there is independent warrant that Zayd is bashar. Without it, the proof assumes its target.

13. When is a synonymous premise permissible?

Not every argument with near-synonymous terms is faulty. If the minor premise is established independently, and the major is true, the conclusion may properly follow.

The defect called begging the question arises when the very premise in dispute is simply granted without justification. Changing its wording does not resolve the controversy.

For example, “this word occurs in the manuscript because the manuscript contains this word” simply restates an unverified observation. This is a supplementary illustration, not a claim about the wording of the textbook.

14. Taking an accidental feature as essential

ومنها أخذ ما بالعرض مكان ما بالذات
Another error is substituting what holds accidentally for what holds essentially.

Bi-l-dhāt concerns a predicate considered as belonging to a thing in its own relevant respect. Bi-l-ʿaraḍ concerns something attributed to it through a secondary relation or circumstance.

If a term is used in an essential sense in one premise and through an accidental relation in another, it no longer functions as a uniform middle term. The respective modes of predication cannot simply be merged.

15. The passenger and the ship: whose movement?

الجالس في السفينة متحرك، وكل متحرك لا يثبت في موضع واحد
A person seated in a ship is moving, and whatever moves does not remain in one place.

The first statement attributes motion to the passenger through the ship and a relevant frame of reference. The second can take “moving” in another sense, as motion belonging to the subject in the intended respect.

Proper analysis asks relative to what reference point motion is asserted, and whether the motion is intrinsic to the person or attributed through the ship. The text’s example warns against merging these respects.

16. The middle term must recur in full

ومنها: أن لا يتكرر الأوسط بتمامه
Another defect is the failure to repeat the middle term in its entirety.

In a categorical syllogism, the middle term must connect the two premises. If one premise contains a term as part of a larger construction and the other uses that word with a different logical role, the required link is absent.

Merely seeing a word twice is insufficient. Its full logical unit and scope must remain the same. The following source example uses “hair” to exhibit this failure.

17. The hair example and its invalid conclusion

الإنسان له شعر، وكل شعر نبت
A human has hair, and every hair is something that grows.

The purported conclusion is الإنسان نبت
Therefore the human is a plant.

Having hair is not the same as being hair. The first premise concerns a part or possession of a human; the second concerns hair itself. The growth predicate belongs to hair, not automatically to the whole person.

At most one may conclude that a human possesses something that grows. A property of a part is not automatically a property of the whole.

18. Potentiality and actuality as distinct respects

ومنها: أن لا يكون الأوسط متشابهاً في المقدمتين لاختلافه بالقوة والفعل
Another error is that the middle term is not the same in the two premises because of a difference between potentiality and actuality.

In potentiality (bi-l-quwwa) means possessing a capacity whether or not it is currently exercised. In actuality (bi-l-fiʿl) means exercising it at the moment or having the realized state.

Someone may have the capacity to speak while currently being silent. Confusing the capacity with its exercise makes a single word carry two different meanings across an inference.

19. Silent and speaking: the source example

الساكت متكلم، والمتكلم ليس بساكت
A silent person is a speaker, and a speaker is not silent.

The first “speaker” may mean someone able to speak, while the second means someone currently speaking. Equating them yields the absurd conclusion that a silent person is not silent.

The remedy is to distinguish the two predicates explicitly: “A silent person may be capable of speech,” and “A person speaking at this moment is not silent at that moment.” Both may be true because they concern different respects.

20. How the placement of a restriction changes meaning

ومنها: اختلاف التركيب بسبب شك
Another fallacy comes from a doubtful or ambiguous construction.

A restriction such as “only,” “alone,” “always,” or “every” may qualify the subject, the predicate, or a whole proposition. Moving it from one position to another can change the quantification and truth conditions.

The question is what the restriction actually governs. If its scope shifts between the premises and conclusion, the needed identity of logical terms has been lost.

21. What follows from “only humans laugh”?

الإنسان وحده ضاحك، وكل ضاحك حيوان
Only the human laughs, and every laugher is an animal.

The invalid conclusion is الإنسان وحده حيوان
Only the human is an animal.

The restriction waḥdahu is attached to the attribution of laughter to humans. The other premise says that laughers belong to the wider class of animals. This does not restrict the entire class of animals to human beings; many non-human animals exist.

One may infer that these laughers are animals, not that everything animal is human.

22. A worked scope comparison

ExpressionWhat it asserts
Only humans laughThe class of laughers is limited to humans
Every laugher is an animalLaughers belong to the broader animal class
Only humans are animalsNo non-human animals exist; not entailed

The fallacy transfers exclusivity of one property to exclusivity of a genus. A restriction must be kept within the scope it actually governs.

23. Confusing a predicate’s concept with its extension

ومنها: سوء اعتبار الحمل
Another fallacy is a mistaken way of regarding predication.

A term’s being predicable of an object is not identical with attributing a logical or mental property to the concept of that term. Since “animal” applies to humans, it does not follow that every property ascribed to the concept *animal* applies in precisely the same way to human individuals.

Watch for a term used in one premise with reference to its extension or instances and in another with reference to its conceptual or logical status. These respects cannot be merged without justification.

24. Why “animal is a genus” can be misused

كل إنسان حيوان، والحيوان عام أو جنس أو مقول على كثيرين مختلفي الحقيقة
Every human is an animal, and animal is a general term or genus predicable of many different species.

A mistaken conclusion is كل إنسان عام أو جنس
Every human is a general term or genus.

“Animal” is predicable of each human as part of their nature; being a genus is a logical classification of the universal concept relative to species. It is not a physical or essential property of every individual person.

Keeping the two levels of discourse separate removes the fallacy.

25. External individuals and second-order logical properties

Two levels must be distinguished:
1. The level of individuals and essences: a human belongs to the animal genus.
2. The logical level: the concept “animal” is called a genus because it applies essentially across different species.

“Zayd is an animal” predicates a nature of an individual. “Animal is a genus” classifies a universal concept in logic.

Both statements may be true, but “Zayd is a genus” does not follow. The predicate has shifted levels.

26. The scope of negation and the copula

ومنها: ما يقع بسبب تقدم الروابط وتأخرها عن السلوب
Another mistake arises from the relative positions of copulas and negations.

The text compares formulations such as زيد ليس هو بقائم and زيد هو ليس بقائم. Their analysis depends on whether negation denies the predication itself or enters into the expression being predicated.

The essential question is whether negation has scope over the proposition or forms part of a negated predicate. Failing to separate these can confuse negative, negative-term, and modal propositions.

27. Not necessarily versus necessarily not

بالضرورة أن لا يكون
It is necessary that it not be.
ليس بالضرورة أن يكون
It is not necessary that it be.

The first asserts necessary non-occurrence, while the second merely denies necessary occurrence. They are not equivalent. “This meeting need not occur” does not mean “this meeting must not occur.” The meeting could be possible but not necessary.

In modern notation, □¬P differs from ¬□P. The first necessitates the negation; the second denies the necessity of affirmation.

28. Repeated negations and what they actually deny

The text also calls attention to multiple negations in one expression. A negation of a negation may yield affirmation, but only when the scope and level of the two negations are identified correctly.

Negating a negation is not identical to denying necessity. “It is not true that Zayd is absent” and “Zayd’s presence is not necessary” express different claims.

Therefore, merely counting the words “not” is insufficient. We must identify what each negation governs and at which logical level it operates.

29. Comparison of the major fallacies in this level

FallacyPrimary defect
Defect of matterPremise truth or intended content
Defect of formAn inference pattern that does not entail its conclusion
Begging the questionThe conclusion is already assumed
Accidental as essentialAn indirectly attributed feature is treated as intrinsic
Changed middle termA qualification, potentiality, or actuality changes its sense
Faulty predicationA property of a concept is passed to its instances
Misplaced negationThe scope of negation or modality changes

30. A practical method for repairing an argument

A reliable diagnostic procedure is:
1. State the conclusion separately: what exactly is being claimed of what subject?
2. Check the truth and qualifications of each premise.
3. Identify the middle term; compare its sense, relation, and scope across premises.
4. Test the productive conditions of the figure and locate any negations.
5. Separate what is genuinely entailed from any additional claim that was not established.

The purpose is not merely to name a fallacy; it is to identify where the inference fails and how the defect could be repaired.

31. Consolidation and the next source boundary

The first substantial group of semantic fallacies requires separate analysis of matter and form. A premise can be true in one respect but illegitimately deployed in another, and true premises can be arranged in a form that proves nothing.

The characteristic examples are the qualified use of “rational,” the unproductive time-and-sphere inference, begging the question, accidental motion of the passenger, incomplete repetition of the middle term, potential versus actual speech, the scope of “alone,” logical predicates of universals, and misplaced negation.

The following source section continues with mental considerations, part–whole and causal errors, priority relations, and famous fallacies. These belong to the remaining discussion of errors arising from meaning.