This thread is beginning to take a turn into retarded philosphy. Soon we'll be reading about how we're all butterflies dreaming we're whelks or something.
Of course we don't KNOW for certain, that's why this debate rages daily. Some people will approach things logically and others will approach it intuitively/emotionally.
When you're getting to the point of defining reality, you're bickering just to be obnoxious.