The problem is that the polygraph doesn't work on both levels. Obviously, it doesn't detect lies. But more to the point, it also doesn't extract useful informat

The problem is that the polygraph doesn't work on both levels. Obviously, it doesn't detect lies. But more to the point, it also doesn't extract useful information from most liars, and leads to fake confessions. To stay in your metaphor: - Not only do sugar pills not cure tumors, but imagine - 60% of recipients don't report decreased pain levels (no placebo effect) - 20% of recipients feel more pain