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example
A '''valid argument''', in [[formal logic]], one in which the conclusion is correctly derived from the premises.
A '''valid argument''', in [[formal logic]], one in which the conclusion is correctly derived from the premises. That is, a valid argument is one in which, if the premises are true, the conclusion must also be true. A valid argument whose premises are true is called a '''sound argument''', and its conclusion must be true.
{{quotebox|A deductive argument is said to be valid when the inference from premises to conclusion is perfect. [http://www.google.com/url?sa=t&ct=res&cd=4&url=http%3A%2F%2Fwww.philosophypages.com%2Flg%2Fe01.htm&ei=bmLhR-jcEpyEygSC_KHZCQ&usg=AFQjCNGAdQx_uQsww5UmvYyOy8eUkMkrGA&sig2=t_MZ8Dqpj6mfQWYpq_aYjA]}}
A valid argument whose premises are not all true is called a '''valid but unsound argument''', and its conclusion is not necessarily true. The following is an example of a valid but unsound argument, in which one of the premises is untrue, so that the conclusion cannot be relied upon (and is wrong):
*Grass is green.
*All green things taste like limes. (untrue premise)
*Therefore, grass tastes like limes.
{{quotebox|A deductive argument is said to be valid when the inference from premises to conclusion is perfect. [http://www.philosophypages.com/lg/e01.htm Arguments and Inference: truth and validity] }}
[[Category:Logic]]