Others have to come up with some alternative theory if they don't believe that.

Within the movement, there are alternative theories about what may have happened.

But what the emotions really are, I don't have an alternative theory.

I do not know if any of these alternative "theories" are true.

Then there's an alternative theory that could be a combination of what we're both saying.

However, it developed an alternative theory of value and distribution.

In response to Said's argument, several alternative theories were proposed.

Have you any alternative theory which will meet the facts?

The article also offered two alternative theories on the origin of town's name.

He offered no alternative theories, essentially moving the investigation back to Day 1.