If Thorn or the Kal should fall or become pressed, Jon would know.
Jon would never know if the Kal or Thorn died. There's no reason for him to know, anyway. 
mnli hypothesis: Jon would never know if the Kal or Thorn died. There's no reason for him to know, anyway.  premise: If Thorn or the Kal should fall or become pressed, Jon would know.