sound argument ,

"The only thing I can say is, we thought we had a sound legal argument and are somewhat disappointed with the outcome," he said.

Then curiously enough, George's slow mind brought forth an even sounder argument.

There are sound arguments for full civilian control.

"But you can make an equally sound argument for getting it all behind you as this new administration comes in."

The party relied on sound political arguments in persuading the opposition lawmakers to vote with the government, he said.

There are sound practical arguments for the policy.

That was a perfectly sound argument, and he didn't even listen to it.

This seems to me a very sound argument; though I do wonder to how many cases of literary mistake it actually applies.

There are sound arguments why banks should not charge anything at all for electronic cross-border payments.

There are sound arguments for stopping using them immediately.