Liberal commentators bemoan the demise of the old John McCain they thought they knew and loved.  Joe Klein wonders what happened to the guy who originally sponsored the Dream Act to allow children of illegal immigrants to become citizens. Think Progress points out that he is now supporting the tax cuts to the rich he vilified in 2000-2004.  What has happened to John McCain? Have his preferences changed?

There is one obvious theory that seems to make his positions consistent: McCain had to run to the right to beat off a primary challenger in Arizona.  But, as Joe Klein points out, “he recently won reelection and doesn’t have to pretend to be a troglodyte anymore.”  So this theory is flawed.

There is another obvious theory.  In this one, you have to identify an outcome a person supports or opposes not just by the policy itself but also by the the other person who supports it.  So you have outcomes like “tax policy opposed by Obama,” “tax policy supported by Bush,” “tax policy supported by Obama,” “tax policy opposed by Bush” etc.  Then, it is quite consistent for McCain to support a 35% tax on the rich when Bush opposes it but to oppose a 35% tax on the rich when Obama proposes it. Essentially, if McCain loses to someone in a Presidential election or primary he opposes their policies whatever they are.

A sophisticated model along these lines is offered by Gul and Pesendorfer.  It allows one person’s preferences to depend on the “type” of the other person, e.g. is the opponent selfish or generous? In principle, this model allows us to determine whether a person is spiteful using choice data.  McCain certainly has some behavior that is consistent with spitefulness.  Is he ever generous?  We would need to know his choices when facing someone he beat in a contest or someone he has never played.  Or is he just plain mean?  Joe Klein leans towards spite based on the available data:

“He’s a bitter man now, who can barely tolerate the fact that he lost to Barack Obama. But he lost for an obvious reason: his campaign proved him to be puerile and feckless, a politician who panicked when the heat was on during the financial collapse, a trigger-happy gambler who chose an incompetent for his vice president. He has made quite a show ever since of demonstrating his petulance and lack of grace.

What a guy.”

If choice with interdependent preferences can be utilized in empirical/experimental analyses, we can investigate the soul of homo economicus using the revealed preference paradigm.