"So there must be some rational explanation for how big it is."

There had to be some sort of rational explanation for all this.

All the rational explanations for what he believed had just happened came to mind now.

But there could be a rational explanation for that, too.

No one could do that; there had to be a rational explanation.

There's probably a very rational explanation for all of this.

Then we will see how I and others respond to your rational explanation.

We don't need a rational explanation for it, at least not right away.

A rational explanation of an attack was much better than the unknown.

"There has to be a rational explanation for this," he said.