Fair Witness
One of the concepts from Heinlein's SISL that I always loved is the Fair Witness. I found this cute little teaching story expressing the concept on a Heinlein Forum:
Three Heinlein characters took a trip to Scotland and drove through the countryside. They passed a farm where they saw a herd of cows with dark brown hides.
"Wow," said Ben, "All the cows in Scotland have brown hides."
"You mean," said Mike, "All the cows in this herd have brown hides."
"All the cows in this herd that we can see, " cautioned Anne, "have brown hides on the side facing us."
Three Heinlein characters took a trip to Scotland and drove through the countryside. They passed a farm where they saw a herd of cows with dark brown hides.
"Wow," said Ben, "All the cows in Scotland have brown hides."
"You mean," said Mike, "All the cows in this herd have brown hides."
"All the cows in this herd that we can see, " cautioned Anne, "have brown hides on the side facing us."