Definition:Valid Argument

Definition
A valid argument is a logical argument in which the premises provide conclusive reasons for the conclusion.

When a proof is valid, we may say one of the following:
 * The conclusion follows from the premises;
 * The premises entail the conclusion;
 * The conclusion is true on the strength of the premises;
 * The conclusion is drawn from the premises;
 * The conclusion is deduced from the premises;
 * The conclusion is derived from the premises.

Sometimes the term sound is found instead of valid.

Proof
If all the premises of a valid argument are true, then the conclusion must also therefore be true.

It is not possible for the premises of a valid argument to be true, but for the conclusion to be false.

A valid argument whose premises are all accepted as true is known as a proof.

Also see

 * Invalid argument
 * Sound argument

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.