It is What It Is. Or is it?

 Saying it is doesn't mean it is because it might not be or does not have to be.  But saying "it is what it is" means it is and always will be because it can't be something else. So, "is it what it is" but does it always have to be?  What if we say it is what it is and it's not but people want you to believe it is.  It might not be what it is but may be something else. So perhaps it's not what it is and IT is an illusion and 'what it is" is actually undefined? Do we just say "it is what it is" because we really don't know what it is?  

That' it!