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.
In my opinion, what makes a designer competent is precisely their ability to credibly justify their conclusions. If you can’t do this as a designer—no matter how successful your results are—then neither I nor anybody else can tell if you aren’t just picking things at random.
What I am proposing, then, is no less than to make a designer’s entire line of reasoning a matter of permanent record. On the surface is the familiar set of prescriptions, components, examples and tutorials, like you would expect out of any such artifact. Attached to every element, though, is a little button that says You click it, and it tells you. The proximate explanation will probably not be very satisfying, so you click on the next until you get to the end, at which point you are either satisfied with the explanation, or you aren’t.