My approach to what I do in my job — and it might even be the approach to my life — is that everything I do is the most important thing I do. Whether it’s a play or the next film. It is the most important thing. I know it’s not going to be the most important thing, and it might not be close to being the best, but I have to make it the most important thing. That means I will be ambitious with my job and not with my career. That’s a very big difference, because if I’m ambitious with my career, everything I do now is just stepping-stones leading to something — a goal I might never reach, and so everything will be disappointing. But if I make everything important, then eventually it will become a career. Big or small, we don’t know. But at least everything was important.
A theory of change is the opposite of a theory of action — it works backwards from the goal, in concrete steps, to figure out what you can do to achieve it. To develop a theory of change, you need to start at the end and repeatedly ask yourself, “Concretely, how does one achieve that?”
The McNamara fallacy, named for Robert McNamara, the US Secretary of Defense from 1961 to 1968, involves making a decision based solely on quantitative observations (or metrics) and ignoring all others. The reason given is often that these other observations cannot be proven.
The fallacy refers to McNamara's belief as to what led the United States to defeat in the Vietnam War—specifically, his quantification of success in the war (e.g., in terms of enemy body count), ignoring other variables.