The primary thing when you take a sword in your hands is your intention to cut the enemy, whatever the means. Whenever you parry, hit, spring, strike or touch the enemy’s cutting sword, you must cut the enemy in the same movement. It is essential to attain this. If you think only of hitting, springing, striking or touching the enemy, you will not be able actually to cut him.
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.
Slack embodied the belief, so common in Silicon Valley, that the best product would win in the end. “Building a product that allows for significant improvements in how people communicate requires a degree of thoughtfulness and craftsmanship that is not common in the development of enterprise software,” the company wrote in its open letter to Microsoft. “How far you go in helping companies truly transform to take advantage of this shift in working is even more important than the individual software features you are duplicating.”
And yet, if there’s a lesson of the past four years, it’s that thoughtfulness and craftsmanship only got the company about 10 percent as far as Microsoft did by copy-pasting Slack’s basic design. In its open letter, Slack famously told Microsoft: “You’ve got to do this with love.” In 2020, looking at Slack’s size, the idea seems laughable. What’s love got to do with it?