A heavy snowfall can transform an easy walk into a serious proposition in just a matter of hours.

Certainly I do not; it is a most serious proposition.

You are putting this forward as a serious proposition?

Now, this is the serious proposition which I have to make to you.

Democracy promotion is a more serious proposition, but to make it a doctrine would be neither desirable nor practical.

But I think that's not too serious a proposition, assuming we can establish the sequence of events as you've outlined them to me.

I have a friend there who has made me serious propositions.

This is a big serious proposition with me, I can tell you.

I do not regard the Baxter alternative as a serious proposition.

In the real world, this would be seen as a work of fiction, not a serious proposition.