A Different Kind of Spin

I don’t know Scott McClellan’s educational background. But I’m willing to bet he’s not a lawyer. (Or, at least, not a very good one.) I make this sweeping generalization based on a statement he made in yesterday’s White House press festivities:

MR. McCLELLAN: - these documents make it very clear that the President of the United States fulfilled his duties --

Q Well, that's subject to interpretation.

MR. McCLELLAN: No. When you serve, you are paid for that service. And these documents outline the days on which he was paid. That means he served. And these documents also show that he met his requirements. And it's just really a shame that people are continuing to bring this issue up.

Having spent the better part of the past holiday season studying for the Law School Admission Test (LSAT) I'm now programmed to recognize a failed contrapositive when I see it.

A contrapositive is an inference one can validly derive by properly reversing and negating the subject and the predicate of an argument. Problem is, often people trip themselves up with the reversal and the negation part. Here's an example of a statement with an invalid inference showing a common error:

If I study I will get a good grade.
I got a good grade THEREFORE I studied.

On it's face the claim seems valid. But when you examine the argument, it's fairly easy to see why it's invalid. Perhaps, instead of studying, I meet Dubya at the bar for drinks and a few lines of coke before I cheated on the test to get my good grade. Getting a good grade does not prove I studied.

This invalid argument takes the form of:

IF A THEN B --therefore--> IF B THEN A

The contrapositive can be formed only by negating and reversing the subject and predicate in a very specfic way. Here's a statement and its valid contrapositive:

If I study I will get a good grade.
I did not get a good grade THEREFORE I did not study.

This argument takes the form of:

IF A THEN B --therefore--> IF not B THEN not A

Getting the good grade does not imply my having studied. Given these facts getting a good grade does not allow me to draw any further conclusions. Only if I did not get a good grade can I make a valid inference.

Which brings us back to Mr. McClellan: "When you serve, you are paid for that service. And these documents outline the days on which he was paid. That means he served."

Let's plug it in to the handy diagram:

GW serves --> GW paid
GW paid --> GW served

It's easy to see the model McClellan is following here. It's the invalid:

A --> B :: B --> A

Rather than the valid contrapositive in the form

A --> B :: not B --> not A

The valid contrapositive tells us:

not GW paid --> not GW served

So what we're really able to derive from Bush's paystubs is...that Bush was paid.

McClellan's error is called circular reasoning. And since McClellan is paid to spin I guess (to use his reasoning) he must be getting paid too.