First, a disclaimer. I'm not a psychologist, psychiatrist, or know anything about the mind, other than some critical thinking. The following stuff is UNTRIED, UNTESTED "common sense" sort of approach I would take if I were to approach someone in a similar predicament.
My approach is... asking questions, Socratic questions. But this is NOT a quick fix. Undoing the knot will take a lot of time, and a lot of questions. This is my personal idea, based on Socratic Questions (as explained in Skeptoid #384). I hope this is of use to people, and I welcome any feedback. Any way...
You will probably need an empty work area, preferably with a big table where you can spread stuff out, a computer to do research on various topics, and a big stack of index cards. Figure at least 100, if not 200 cards, and a few pens, different color (you use one color for questions, he uses another for answers). You will definitely need one big red marker in addition to other colored pens.
And finally, you will need several hours, with refreshments and snack breaks in between, but NO CELLPHONES. The idea is to get the victim AWAY from his/her upline's influence for a while.
And you will need a quick lesson in critical thinking, and understand what is a "null hypothesis". I suggest you research a bit of critical thinking on your own before you attempt this "intervention". Null hypothesis is best described as unknown / indeterminate state. If the premise is "WooPlus cures cancer", the null hypothesis would be "we don't know whether WooPlus cures cancer or not". the ANTI-premise is "WooPlus does NOT cure cancer". Facts and Logic (evidence) are suppose to move you from null hypothesis toward the premise. When there's not enough evidence you're left with the null hypothesis, not the anti-premise. Yet many people mistake the critical thinking process into thinking that it's either the premise, or the anti-premise, with no null hypothesis.
In the future, I may publish some of the better questions to ask, though this is highly dependent on the individual subject.
NOTE: If you cannot finish this in one sitting, you may want to pick a smaller premise, like "WooPlus product is effective for _____" first. Or perhaps ask for help analyzing his answers, even online. Just don't let him consult upline (yet). If questioned, reply that you want to get to the facts, which are easily Googled, instead of relying on someone else's memory.
There are three general phases:
- Engage and clarify premise with supporting evidence and logic
- Identify ambiguities, assumptions, and logical fallacies
- Re-examine premise with multiple perspectives