modus tollens: meaning, definition, pronunciation and examples
RareFormal, Academic, Technical
Quick answer
What does “modus tollens” mean?
A rule of logical inference meaning 'the mode of denying' – it denies the consequent of a conditional statement to deny the antecedent.
Audio
Pronunciation
Definition
Meaning and Definition
A rule of logical inference meaning 'the mode of denying' – it denies the consequent of a conditional statement to deny the antecedent.
In propositional logic, it is a valid argument form: If P, then Q. Not Q. Therefore, not P. It is also known as denying the consequent.
Dialectal Variation
British vs American Usage
Differences
No significant differences in meaning or usage between UK and US English. Both use the same Latin term.
Connotations
Purely logical, academic, and technical connotations in both varieties.
Frequency
Extremely rare outside specific academic fields (logic, philosophy, mathematics) in both regions.
Grammar
How to Use “modus tollens” in a Sentence
[Subject] + applies/uses + modus tollens + [to deduce/conclude] + [result].Vocabulary
Collocations
Usage
Meaning in Context
Business
Virtually never used.
Academic
Used in logic, philosophy, mathematics, computer science, and critical thinking courses to denote a specific rule of inference.
Everyday
Not used in everyday conversation.
Technical
Used precisely in technical discussions of formal logic, argument structure, and automated reasoning systems.
Vocabulary
Synonyms of “modus tollens”
Neutral
Weak
Vocabulary
Antonyms of “modus tollens”
Watch out
Common Mistakes When Using “modus tollens”
- Misspelling as 'modus tokens' or 'modus tolens'.
- Confusing it with 'modus ponens' (affirming the antecedent).
- Using it to describe everyday, non-formal reasoning patterns.
FAQ
Frequently Asked Questions
No. It is a specialised term from formal logic and is almost exclusively used in academic, philosophical, or technical contexts.
Modus ponens affirms the antecedent to affirm the consequent (If P then Q; P; therefore Q). Modus tollens denies the consequent to deny the antecedent (If P then Q; not Q; therefore not P).
If it is raining, the street is wet. The street is not wet. Therefore, it is not raining.
In classical propositional logic, yes, it is a valid deductive argument form. Its validity relies on the truth of the conditional premise 'If P then Q'.
Modus tollens is usually formal, academic, technical in register.
Modus tollens: in British English it is pronounced /ˈməʊdəs ˈtɒlɛnz/, and in American English it is pronounced /ˈmoʊdəs ˈtɑːlənz/. Tap the audio buttons above to hear it.
Learning
Memory Aids
Mnemonic
Modus TOLLens TOLLs (rings) the bell for the consequent Q, saying 'Q is false', which knocks down the antecedent P.
Conceptual Metaphor
LOGICAL DEDUCTION IS A PATH (You take the path of denying the consequent to reach the denial of the antecedent).
Practice
Quiz
What is the common English name for 'modus tollens'?