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Modus Tollens

Disciplines > Argument > Syllogisms > Modus Tollens

Description | Example | Discussion | See also

Description

If X is true then Y is true.

Y is false.

Therefore X is false.

Example

If there is smoke, there is fire. There is not fire, so there is no smoke.

If I am happy, then I smile. I am not smiling, therefore I am not happy.

Discussion

Modus Tollens is not as straightforward as its companion, Modus Ponens. Although common in argument, a Modus Tollens is not necessarily true, as the major premise (If X is true then Y is true) says nothing about falsehood. If, however, X and Y are bivalent (both can be either true or false) and X can only be true if Y is true, then the Modus Tollens stands.

Modus Tollens is the root of falsification, as proposed by Karl Popper and since used as the cornerstone of scientific proof.

This is also known as Denying the Consequent, as Y, the consequent is being denied as being true.

See also

Conditional Reasoning, Denying the Antecedent, Affirming the Consequent, Modus Ponens

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Site Menu

| Home | Top | Quick Links | Settings |

Main sections: | Disciplines | Techniques | Principles | Explanations | Theories |

Other sections: | Blog! | Quotes | Guest articles | Analysis | Books | Help |

More pages: | Contact | Caveat | About | Students | Webmasters | Awards | Guestbook | Feedback | Sitemap | Changes |

Settings: | Computer layout | Mobile layout | Small font | Medium font | Large font | Translate |

Please help and share:

Quick links

Disciplines

* Argument
* Brand management
* Change Management
* Coaching
* Communication
* Counseling
* Game Design
* Human Resources
* Job-finding
* Leadership
* Marketing
* Politics
* Propaganda
* Rhetoric
* Negotiation
* Psychoanalysis
* Sales
* Sociology
* Storytelling
* Teaching
* Warfare
* Workplace design

Techniques

* Assertiveness
* Body language
* Change techniques
* Closing techniques
* Conversation
* Confidence tricks
* Conversion
* Creative techniques
* General techniques
* Happiness
* Hypnotism
* Interrogation
* Language
* Listening
* Negotiation tactics
* Objection handling
* Propaganda
* Problem-solving
* Public speaking
* Questioning
* Using repetition
* Resisting persuasion
* Self-development
* Sequential requests
* Storytelling
* Stress Management
* Tipping
* Using humor
* Willpower

Principles

Explanations

* Behaviors
* Beliefs
* Brain stuff
* Conditioning
* Coping Mechanisms
* Critical Theory
* Culture
* Decisions
* Emotions
* Evolution
* Gender
* Games
* Groups
* Habit
* Identity
* Learning
* Meaning
* Memory
* Motivation
* Models
* Needs
* Personality
* Power
* Preferences
* Research
* Relationships
* SIFT Model
* Social Research
* Stress
* Trust
* Values

Theories

* Alphabetic list
* Theory types

And

– About
– Guest Articles
– Blog!
– Books
– Changes
– Contact
– Guestbook
– Quotes
– Students
– Webmasters

| Home | Top | Menu | Quick Links |

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