Necessity vs. Sufficiency

What’s needed is not enough.

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What’s needed is not enough.

When we try to extract the factors that create a particular condition, we quickly get stuck with commonalities between different observations.

For example, when we analyse why people are successful in business, we might look at what all successful business people have in common.

But even if there is something that all have indeed in common (e.g. working really hard), this doesn't tell us much about whether that thing will make us successful. It only tells us that without hard work, we can't become successful. There will be lots of people who work very hard, but aren't successful.

Hard work is necessary for success, but it's not sufficient. In other words, you can't be successful without hard work, but hard work is not a guarantee for success.

Likewise, whenever we try to find out how something comes about, there's almost always something that's necessary, but not sufficient by itself. Usually, sufficiency is the result of a combination of factors, each single one potentially necessary.

In general, a necessary condition is one which must be present in order for an event to occur — but it alone doesn't provide sufficient cause for the occurence. A sufficient condition, however, is one which will definitely cause the event.


➞ For a great and understandable introduction, check out this Khan Academy article.

➞ If you want to understand even more, read this Wikipedia article.


For a structured list of fascinating booksblogspodcasts, and Youtube channels related to logic and reasoning, visit

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