Definition
Binary thinking is the habit of compressing a continuous spectrum — incomes, beliefs, outcomes, identities — into two discrete buckets, usually labelled in opposition: rich/poor, developed/developing, success/failure, us/them.
A binary is easy to remember, easy to argue with, and easy to vote on. It also distorts. Most real distributions are continuous, with most of the mass somewhere in the middle and a small tail at each end. Imposing two buckets makes the middle disappear and the tails carry the meaning of the whole.
Why it matters
How it works
Binary thinking is the engine of the gap instinct in Rosling's scheme. The gap instinct splits humanity into two camps with a gap between; binary thinking is the cognitive operation that does the splitting. The two are so closely linked that fixing one usually fixes the other.
The operational fix is to swap the binary for a small number of levels. Rosling's four income levels — roughly $2, $8, $32, and above per person per day — replace a single rich/poor split with a four-step ladder that captures most of the world's variation. The same trick works elsewhere: replace "smart vs. not smart" with a range of demonstrated competencies; replace "with us or against us" with a spectrum of agreement; replace "success or failure" with grades of partial achievement.
The deeper move is to notice when a binary is being used as a rhetorical tool rather than a descriptive one. Political language reaches for binaries because they mobilise; analytical language should reach for distributions because they explain. When a binary feels obligatory, the question to ask is what the middle would look like if it were allowed to exist.