The Definition of Validity
To understand the validity of an argument, you have to understand what validity is. The definition of validity says that neither do the premises have to be true nor does the conclusion have to be true. Basically validity means if A is true, then the conclusion has to be true. The validity is there even if the premise is totally ridiculous. Here is an example:
All cats have three heads,
The university professor is a cat,
Therefore, the university professor has three heads.
Valid is considered a technical term and an argument can be considered valid no matter how false the information presented is.
In the example, suppose it is true that all cats have three heads, and pretend, just pretend that the university professor is a cat. In this imaginary scenario, the conclusion, “the university professor has three heads” has to be true. So this argument is valid even though the premises are false and the conclusion is false.
A valid argument should never take you from the true premises to a conclusion that is false. If you present a sound argument from any given conclusion and that argument has true premises, that argument is considered valid. Arguments that are valid cannot take one from true premises to a false conclusion. This would make the argument’s conclusion true. An argument that is sound always have true conclusions. This would mean if read someone’s argument and you disagree with that argument, you have to claim the argument as unsound. Either that argument does not follow the premises or there is an issue with logic or reasoning. It could be that only one of the premises is false.