Dangers of Interpreting Silence

Writing at EconLog, David Henderson has an excellent short article on his experiences circulating a letter on the 1990 Invasion of Iraq, namely the political claim at the time that Saddam could use his power over the oil market to inflict harm on our economy.

The economics of his argument is interesting enough, but I want to draw attention to some prominent names who did not sign his letter:

Gary Becker
Paul Samuelson
Sam Peltzman

All three are highly renowned economists, and two are Nobel laureates.  Why did they refuse to sign the letter?  Did they know something Henderson did not?  Did they disagree with the analysis?

Fortunately, Henderson gives us some insight into the matter:

Gary S. Becker: I agree with the economic point you made. But I won’t sign. I’m not a signer. Also, Saddam Hussein is a threat in other ways. But I agree that the threat does not arise from his power over the price of oil.

Paul A. Samuelson: This war isn’t about the price of oil.

Henderson: Maybe it’s not but that’s the justification that’s being given by Bush and Baker. [I should have said “one of the main justifications.”]

Samuelson: It is and it isn’t. But I won’t sign.

Henderson: Do you agree with my analysis?

Samuelson: I don’t have any quarrel with your analysis.

Henderson: If I’m ever asked, can I quote you to that effect?

Samuelson: (Pause.) Sure. Your analysis was correct.

 

Sam Peltzman: The analysis is right but I won’t sign.

Henderson: Can I quote you as saying the analysis is right?

Peltzman: Why do you want to quote me?

Henderson: You’re a name. You said the same thing that Paul Samuelson, Murray Weidenbaum, and Gary Becker said. You guys are names. Can I quote you?

Peltzman: Sure. I don’t care.

All three men agreed with the economic analysis but refused to sign for other reasons.  Without this information, however, it might have been concluded by an analyst that Becker, Samuelson, and Peltzman disagreed with the fundamental analysis; a conclusion we now know would have been incorrect.

Fortunately for us, Henderson was able to keep meticulous records of these conversations.  But if we did not have that record (or could still ask Peltzman as he is still alive), we would have to rely on the evidence of what was actually said/done.  The silence of Becker, Samuelson, and Peltzman would provide no evidence of their opinion on Henderson’s letter.

This story is important given a recent debate on whether or not Jim Buchanan and Public Choice was inherently racist, or somehow a reaction to integration movements in the US.  Nancy MacLean and her supporters have recently constructed an argument that Buchanan was silent on the possibility of his ideas being used to perpetuate segregation and therefore tacitly endorsed such behavior (note this is a switch from MacLean’s position in her book where she claims such support was more manifest).  But they are making the mistake of arguing from lack of evidence.  It would be akin to saying Becker must have opposed Henderson’s argument because Becker did not sign.

Lack of evidence is not the same as evidence.  It is not evidence that I am Batman just because I and Batman have never been seen in the same room.  Likewise, it is not evidence Buchanan was a segregationist or sympathetic to them just because he was silent on the issue.