Brittany M.

asked • 09/12/21# Is the following argument valid or invalid?

On vacation I'll either go to the beach or I'll swim in the pool.

I went to the beach.

Therefore, I didn't swim in the pool.

## 2 Answers By Expert Tutors

This argument is **invalid.**

In logic, the 'or' connective (also called 'disjunction') is *inclusive*. This means that if 'X or Y' is true, then it's possible that *both* X and Y are true.

In your example, you suppose that B or P is true, then suppose that B is true. Since 'or' is inclusive, this is perfectly compatible with P being true, too -- so we cannot validly conclude ~P, as your example does.

On vacation I'll either go to the beach or I'll swim in the pool.

I went to the beach.

Therefore, I didn't swim in the pool.

Change your sentence to variables, like the other tutor said.

p v q

p

~q

If *P*, then *Q*.

*P*.

Therefore, *Q*.

instead, we have not Q

in logic, if you have an OR, as long as one is true, it's ok.

Check with the other answer for more details as well, but this is a Modus Ponens, MP style logical question.

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Robert B.

11/17/21