Logical Thinking · Lesson 3 of 4

Necessary, sufficient, and common fallacies

Necessary is not sufficient. Much effort goes into satisfying necessary conditions and then stopping.

6 min read · Free — no account needed to read

A necessary condition must be present for something to happen; a sufficient condition is enough on its own to make it happen. A portfolio may be necessary to get hired and nowhere near sufficient. Treating one as the other produces a lot of wasted effort aimed at the wrong thing.

Named fallacies are simply common ways the link between premises and conclusion fails. Attacking the person rather than the claim. Assuming what you set out to prove. Appealing to what is popular or traditional as if popularity settled it. Sliding from a modest step to a catastrophic end with nothing in between.

You do not need the Latin. You need the habit of asking one question of every argument: does this conclusion actually follow from these reasons, or does it merely sound like it does?

See it happen

You have rewritten your CV, and the applications are still going nowhere.

The read that arrives on its own

The CV must still be wrong. Rewrite it again.

The same situation, with this idea

A decent CV is necessary — nothing happens without one. It is not sufficient. Am I applying to roles that match, am I applying early, is anyone inside the company aware of me?

What changed

Enormous effort goes into satisfying a necessary condition and then stopping there, because it feels like the work is being done.

The takeaway

Necessary is not sufficient. Much effort goes into satisfying necessary conditions and then stopping.

Easy to take the wrong way

Reading "not sufficient" as "does not matter". A necessary condition is still load-bearing — it is just not the whole bridge.

Try this

Pick a goal you hold. List what is necessary for it and, separately, what would actually be enough.