Invalid vs Unsound Argument

Writing Tip #1

In order for an argument to be considered invalid we must be able to give an example of a possibility in which the premises could be true and the conclusion false at the same time.

Example: Sarah owns a Bearnaise Mountain dog. Rich people own Bearnaise Mountain Dogs. Therefore Sarah must be rich.

“Rich people own Bearnaise Mountain dogs,” does not exclude the possibility that people who are not rich own Bearnaise Mountain dogs.

In an invalid and unsound argument at least one premise is false and the conclusion does not follow the premise.

Example: All humans live under the water.

Everything that is underwater is wet.

Therefore, humans are dry.

The premise that all humans live underwater is false.

It is more important to have a sound argument. You can have a valid unsound argument. You can not have an invalid sound argument. You can have an invalid and unsound argument. This is enough to make ones head spin! Since valid arguments leave room for more the argument to continue I do not find it as effective as a sound argument. In a sound argument the facts are more straightforward.