Definition:Invalid Argument
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Definition
An invalid argument is a argument in which the premises do not provide conclusive reasons for the conclusion.
Sometimes the word unsound is found instead of invalid.
An invalid argument is also known as a fallacy.
Also see
Warning
In natural language, it is commonplace to discuss the validity of statements as being valid or invalid, when what is really meant is that a statement is either true or false.
Linguistic Note
The word invalid, as used in the logical context, has the stress on the second syllable: in-val' -id.
Pronounced in' -val-id, with the stress on the first syllable, the word means a person who is being treated for an illness.
So let's be careful out there.
Sources
- E.J. Lemmon: Beginning Logic (1965): $\S 1.1$
- D.J. O'Connor and Betty Powell: Elementary Logic (1980): $\S 1.1$
