To understand how the pattern works, we will need to enter the realm of paradox, which is very difficult for most of us to think about. (It was also hard for Bertrand Russell and Gottlob Frege, two very brilliant professional logicians to think about, so there is no shame in this, but the faint of heart may wish to consider turning to simpler recreations.)
“Are you sure?” asks if a person is in state of certainty. This is a question that asks for a digital yes or no answer, but permits answers which are qualified in some way.
If the person says, “No, not really,” then they are uncertain (A) and are already open to other understandings.
If they respond, “Well, I'm pretty sure,” they are somewhere in the intermediate range of partial certainty (B) and will be at least somewhat open to considering other understandings.
If they simply respond “Yes,” we need more information. (As usual the nonverbal messages in voice tone, posture, hesitations, etc. will be much more useful than the words in assessing the actual degree of certainty the person is experiencing.)
“Are you sure you're sure?” applies certainty to itself recursively, in essence asking if the person is absolutely sure. Answering this question requires the person to go to a 4th level, applying certainty to itself. Again this is a question that asks for a digital yes or no answer, but permits a qualified answer.
If the person says. “Well, I'm pretty sure,” or qualifies it in any way, then the person is somewhere in the mid-range (B), and can already be talked with usefully. If the person replies with an unqualified “Yes,” they are saying that they are absolutely certain (C). (Again, the nonverbals will tell you more about the absoluteness of the certainty than the words.)
This condition of absoluteness (or near absoluteness) is required for the next step of the pattern to work. However, if the condition of absoluteness is not met, it means that the next step is unecessary, because in a condition of partial certainty (B) you can proceed to usefully explore alternative understandings.
A very important aspect of this question is that it asks the person to recursively apply their certainty to itself. This requires the person to go to a fourth logical level, and this is something which is also necessary for the next step in the pattern. A “Yes” answer is a confirmation that the person is willing and able to do this recursion or “apply to self,” as it is usually called in the “sleight of mouth” patterns. Recursion is a precondition for the next question, which also asks the person to apply certainty to itself, but in a different way.
Another way of describing this is that the first two questions can be used both to gather information about the client's degree of certainty, while at the same time beginning to assemble pieces of a puzzle which will be put all together in the third step.
“Are you sure enough to be UNSURE?” applies certainty to its negation, and is a form of logical paradox, equivalent to the statement “This sentence is false (not true),” or “I am a liar (not truth-telling).” (The word “paradox” can also used in a more general way to mean “contradictory” or “unexpected,” but the meaning here is restricted to logical paradox.)