Validity and soundness are two of the most important concepts in the study of arguments, and they are often confused with one another. Read these three tutorials, starting with A03 and clicking through to A05, on the distinction between valid and sound arguments, their relationship to the truth of the statements that make them up, and the structural patterns that help us to recognize them.

Complete the exercises and check your answers.

### Soundness

It should be obvious by now that validity is about the logical
connection between the premises and the conclusion. When we are told
that an argument is valid, this is not enough to tell us anything about
the actual truth or falsity of the premises or the conclusion. All we
know is that there is a logical connection between them, that the
premises entail the conclusion.

So even if we are given a valid argument, we still need to be careful
before accepting the conclusion, since a valid argument might contain a
false conclusion. What we need to check further is of course whether the
premises are true. If an argument is valid, and all the premises are
true, then it is called a *sound* argument. Of course, it follows
from such a definition that a sound argument must also have a true
conclusion. In a valid argument, if the premises are true, then the
conclusion cannot be false, since by definition it is impossible for a
valid argument to have true premises and a false conclusion in the same
situation. So given that a sound argument is valid and has true
premises, its conclusion must also be true. So if you have determined
that an argument is indeed sound, you can certainly accept the
conclusion.

An argument that is not sound is an *unsound* argument. If an argument is unsound, it might be that it is invalid, or maybe it has at least one false premise, or both.

##### **Exercise #1.**

Is it possible to have arguments of the following kinds? It is particularly important to note
the highlighted cases. Click on each box for the answer.

#####
Exercise #2

Are the following statements true or false?