I’m impressed to learn that Haidt backed up his Five Foundations theory with his own cash.  The offer expired on August 1, 2009, but it ran for two years:

IF ANYONE CAN DEMONSTRATE THE EXISTENCE OF AN ADDITIONAL FOUNDATION, OR
SHOW THAT ANY OF THE CURRENT 5 FOUNDATIONS SHOULD BE MERGED OR
ELIMINATED, JON HAIDT WILL PAY THAT PERSON $1,000.

The resolution procedure is admittedly slanted in Haidt’s favor:

Winning the prize will take two steps. First, you must make a good
case, in writing, that some other set of concerns is a plausible
candidate for foundationhood. Then, you must collect empirical evidence
to show that this set of concerns is psychometrically distinct from the
existing five foundations, or is otherwise incompatible with the
existing five… We in the consortium will be the judges, and we’ll
probably want to replicate anyone else’s findings before changing our
whole theory, but we have stated in print that we take the five
foundations are the best starting points; we do not believe they
account for all of human morality. (emphasis mine)

I’m nevertheless impressed that they’ve publicly named and described the leading challengers: equality/oppression, liberty/oppression, waste, wisdom, truth/right belief, truth/honesty, a bipolar theory, self-control, and property.

Question for discussion: Read the details on the challengers.  Which is the easiest to subsume under the Five Foundations?  The hardest?