valid reason

But is that a valid reason why he should be in the show?

There's not one valid reason why I should try to keep our marriage going by myself.

I can't see any valid reason for not giving, say 30 minutes notice.

One reason, good and valid, she never even thought of.

Am I doing this for any kind of really valid reason?

Someone who had a valid reason to visit him frequently.

Probably because I couldn't give her any, not valid reasons.

There are many valid reasons to have more than one screen name.

This wasn't a valid reason but it was a good one.

Well you got a valid reason for having a fast machine.