What is the point of a big speech outlining your intentions when everybody already knows that when push comes to shove you are just going to do what’s in your interest?  Usually such a speech is all about the reasons for your stated intentions.  If you can change people’s minds about the facts then you can change their minds about your intentions.

But the public facts are already that, public.  There’s no changing minds about those.  At best you can change minds about how you perceive the public facts or about facts that only you know.  But here we are in the realm of private, unverifiable information and any speech about that is pure cheap talk.  You will invent facts to support whatever intentions you would like people to believe.

Except for two wrinkles.

  1. Making up a coherent set of facts that support your case and survive scrutiny is not easy.  On the other hand, the truth is always a coherent set of facts.
  2. You can only say things that you can think of.  That’s a small subset of the set of all things that could possibly be true and the truth is always in that subset.

Together these imply that cheap talk always reveals information.  It reveals that the story you are telling is one of the few coherent stories you could think of.  And if that story is complicated enough it becomes more and more likely that this is the only story that complicated that a) is coherent and b) you could think of.  Since the truth always satisfies a) and b), this makes it ever more likely that what you are saying is the truth.

This is why when we want to change minds we make elaborate speeches full of detail.  It convinces the listener that we are telling the truth.  And this is why when we want to be inscrutable the listener will pepper us with questions in order to require so much detail that only the truth will work.