Such a conjecture is pure supposition.

Your whole theory is based on pure supposition.

That was pure supposition, nothing else.

That's pure supposition.

It's a neat theory but - let's face it, my friend - it's pure supposition.

Look, Conn, we don't know what this Project Merlin was; all this lore about Merlin that's grown up since the War is pure supposition.

Anything else is pure supposition.

The case against Najah is pure supposition.

"Captain, that is pure supposition," Selar said.

It's pure supposition but it's the only supposition which fills the framework of fact.