modus tollens
/ˌməʊdəs ˈtɒlɛnz
/noun
1The rule of logic which states that if a conditional statement (‘if p then q’) is accepted, and the consequent does not hold (not-q) then the negation of the antecedent (not-p) can be inferred.Some philosophers have defended the view that animals are not sentient and attempted to use a component conditional for modus tollens....
- First, although modus ponens has a probabilistic analog, modus tollens does not - the fact that a hypothesis says that an observation is very improbable does not entail that the hypothesis is improbable.
- From a conditional statement, one can construct two types of valid inference: modus ponens and modus tollens.
1.1An argument using the rule of modus tollens.One use of modus tollens is the reductio ad absurdum argument, i.e. showing that a premise is false by demonstrating that it implies an absurd conclusion....
- This argument has the modus tollens form, and hence is valid - if its premisses are true, then its conclusion must be true as well.
- Once this is shown, the consequences invite a modus tollens; the mere vulnerability of proposed reductions is hardly enough to support the view with such exotic consequences.
Origin
Latin, literally 'mood that denies'.