Final answer:
A contradictory premise is when the premises of an argument inherently contain assertions that cannot both be true; for instance, saying "All birds can fly" while also stating "Penguins cannot fly" creates a contradiction, as penguins are related to birds.
Step-by-step explanation:
An example of a contradictory premise is a set of premises that inherently contains opposite assertions that cannot both be true simultaneously. For instance, if someone argues with the following premises:
- All birds can fly.
- Penguins are birds.
- Penguins cannot fly.
This set of premises is contradictory because it simultaneously asserts that all birds can fly and that penguins (which are a type of bird) cannot fly. Such contradictions make any argument invalid because they fail to provide a logically coherent rationale to support a conclusion.
Contradictory premises violate the rules of deductive reasoning because they lead to a conclusion that cannot be guaranteed to be true. The counterexample in this case could simply point to the existence of penguins as a contradiction to the universal claim that all birds can fly, rendering the premise false.
The problems with this type of argument can also be rooted in a fallacy of relevance or circular reasoning, where the premises are inadequate to support the conclusion.