There is a subset of set P, the set of people, which is always a subset of set F, the set of fooled people.
There are times when the set P and set F are equivalent.
EDIT:It's Friday evening, so this is still today's strip. I updated the chart. It didn't seem right to me last night, and I tweaked it. I just didn't tweak it correctly. Oopsie. Lincoln must've been better at this than I am.