Necessity and Sufficiency
Many people confuse necessary conditions (prerequisites) with sufficient conditions (the full set that guarantees success), overlooking that the gap often involves luck or factors beyond control.
THE IDEA
We often make the mistake of assuming that having some necessary conditions in place means that we have all of the sufficient conditions in place for our desired event or effect to occur. The gap between the two is the difference between becoming a published author and becoming J.K. Rowling. Certainly you have to know how to write well to become either, but it isn’t sufficient to become a Rowling. This is somewhat obvious to most. What’s not obvious is that the gap between what is necessary to succeed and what is sufficient is often luck, chance, or some other factor beyond your direct control.
Assume you wanted to build a company that makes it into the Fortune 500. Capital is necessary, but not sufficient. Hard work is necessary, but not sufficient. Intelligence is necessary, but not sufficient. Success on that scale takes more than those inputs, including favorable circumstances outside your control. That’s a big reason that there’s no recipe.
Winning a military battle is a great example of necessity and sufficiency. It is necessary to prepare for the battle by evaluating the strength and tactics of your enemy, and by developing your own plan. You need to address logistics such as supplies, and have a comprehensive strategy that allows flexibility to respond to the unexpected. These things, however, are not enough to win the battle. Without them you definitely won’t be successful, but on their own they are not sufficient for success.
This concept is demonstrated in sport as well. To be successful at a professional level in any sport depends on some necessary conditions. You must be physically capable of meeting the demands of that sport, and have the time and means to train. Meeting these conditions, however, is not sufficient to guarantee a successful outcome. Many hard-working, talented athletes are unable to break into the professional ranks.
A necessary condition must hold for an outcome to occur. A sufficient condition, or combination of conditions, guarantees that outcome. Listing prerequisites does not establish that they are jointly sufficient. A success story can mislead when it treats a few observed ingredients as a complete recipe.
When to use it
Evaluating a startup business plan by distinguishing between essential prerequisites (a great idea, a strong team, capital) and the unpredictable elements that actually determine market success.
Advising students on career paths by distinguishing formal prerequisites from helpful qualifications and from factors such as timing and available jobs.
Assessing a military strategy by identifying all necessary elements (intel, supplies, planning) and reminding planners that unforeseen events can still derail even the best-prepared operation.
FROM THEORY TO EVERYDAY LIFE
In practice
Publishing Success
Knowing how to write well is necessary to become a published author, but it's not sufficient to become J.K. Rowling. The gap includes luck, market timing, and other factors.
Fortune 500 Company
Capital, hard work, and intelligence are necessary to build a billion-dollar business, but they are not sufficient—luck and uncontrollable factors play a large role.
Military Victory
Thorough preparation, intelligence on the enemy, logistics, and a flexible plan are all necessary for winning a battle, but they do not guarantee victory.
Professional Sports
Physical aptitude and rigorous training are necessary to become a professional athlete, but many who have them never reach the top tier because luck, opportunity, and other factors are also required.
A MOMENT TO REFLECT
Put it to work.
Think of a goal you achieved. Which factors were truly necessary, and which were simply helpful? Which ones were sufficient together?
Where in your life might you be mistaking a necessary condition for a guarantee of success?
How can you account for luck and factors outside your control when planning for an important outcome?
CONTINUE THE CONVERSATION
Source texts
- The Great Mental Models Volume 1 General Thinking Concepts