Validity

    Saying that an argument is valid is equivalent to saying that it is logically impossible that the premises of the argument are true and the conclusion false. A less precise but intuitively clear way of putting this is to say that in a valid argument IF the premises are true, then the conclusion must be true.
Arguments of a valid FORM are valid even if they are completely absurd. For example, the following argument is valid:

All women are cats.
All cats are men.
Therefore,
All women are men.

    This argument has false premises and a false conclusion. This brings out the hypothetical character of validity. What the validity of these arguments amounts to is that it assures us the conclusion must be true IF the premises are true.
    If an argument can be valid and yet have a preposterously false conclusion, what good is validity? Why should we be concerned with validity at all? The answer is that a valid argument is truth preserving. Truth in the premises of a valid argument is preserved in the conclusion. Of course, if the premises are not true to begin with, then even a valid argument cannot ensure that the conclusion is true. But ONLY valid arguments are truth preserving. An analogy might help clarify this point. Roughly, valid arguments preserve truth like good freezers preserve food. If the food you place in a freezer is spoiled to begin with, then even a good freezer cannot preserve it. But if the food placed in a good freezer is fresh, then the freezer will preserve it. Good freezers and valid arguments preserve food and truth, respectively. But just as the former cannot preserve food when the food is spoiled, so the latter cannot preserve truth when the premises are false. Nevertheless food freezers and valid arguments are worth having because they do preserve something good when one has it, and without them one may wind up with something rotten even when beginning with something impeccable. Thus validity is to be desired and invalidity is to be eschewed.

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