Arguments: premises, conclusions, and validity
An argument is a set of reasons offered for a claim, and the first philosophical skill is seeing its parts clearly.
Premises and conclusion
In philosophy an argument is not a quarrel. It is a structure: one or more premises, which are the reasons, offered in support of a conclusion, which is the claim being defended. Words like 'because', 'since', and 'given that' usually flag premises, while 'so', 'therefore', and 'it follows that' usually flag the conclusion.
Valid versus sound
An argument is valid when the conclusion would have to be true if every premise were true, so its form leaves no gap. It is sound when it is valid and all of its premises actually are true. A valid argument can still have a false conclusion if a premise is false, which is why critics attack premises as well as form.
Worked example: testing with a counterexample
Consider: 'All good teachers are patient. Maya is patient. So Maya is a good teacher.' To test validity, imagine a case where the premises are true but the conclusion is false: Maya is a patient person who has never taught. Because that case is possible, the argument is invalid. Patience being required for good teaching does not make it enough.
Flashcard
A reason offered in support of a conclusion
Check your understanding
Which argument is valid?