McNamara fallacy

McNamara fallacy

The McNamara fallacy refers to Robert McNamara, the United States Secretary of Defense from 1961 to 1968, and his belief as to what led the United States to defeat in the Vietnam War. It refers to the quantifying of success in the war (e.g. in terms of enemy body count) while ignoring other variables.

The first step is to measure whatever can be easily measured. This is OK as far as it goes. The second step is to disregard that which can't be easily measured or to give it an arbitrary quantitative value. This is artificial and misleading. The third step is to presume that what can't be measured easily really isn't important. This is blindness. The fourth step is to say that what can't be easily measured really doesn't exist. This is suicide.
—Charles Handy, The Empty Raincoat, page 219.


Ted has a lot of money. Lots of money makes a person happy. Ted says that he is depressed. What Ted says doesn't necessarily indicate how he feels. Depression cannot be proven. Therefore, Ted is happy.