Paradox, Self-Reference, Circularity, and Recurrence

Self-Reference Aptitude Test
This is Not the Title of This Essay
Recursive acronyms - e.g. GNU (GNU's Not Unix)

Precede any request with a self-referring yes-no question, e.g.

  If I ask you out, will your answer be the same as your answer to this question?

If the human brain were so simple that we could understand it, we would be so simple we couldn't.
  -- Emerson Pugh

How many mistakes are there in the following sentence?

  Their are three mistakes in this sintence.

Law student Tisias agreed to pay his teacher Korax when he won his first case.  
By some means (choosing another career, losing, or settling cases out-of-court), Tisias avoided
a win and hence did not pay Korax.  Eventually Korax sued Tisias for the tuition.

Tisias defended himself by reasoning as follows: 
  "If I win this case, then I need not pay by judgment of the court.  
   But if he wins, then I need not pay since the terms of the contract have not been fulfilled."

Korax responded with: 
  "If I win, then Tisias must pay me by judgment of the court.  
   But if he wins, then he must pay me because the terms of the contract will have been fulfilled."