Definition
Liking is Cialdini's third weapon of influence: we preferentially comply with requests from people we like. The principle is unsurprising; the contribution is in disaggregating liking into five separable inputs the brain uses to compute it. Each input can be triggered independently, so the operator only needs to score on two or three to flip the verdict from neutral to positive.
The five inputs: physical attractiveness (halo effect — attractive people are presumed more competent and trustworthy), similarity (matching dress, background, opinions, even names), compliments (raise liking even when known to be false), contact and cooperation (repeated cooperative exposure builds positive familiarity), and association (Pavlovian linkage with pleasant stimuli — being paired with good news, attractive models, or favorable outcomes).
Why it matters
How it works
When you must decide quickly whether to trust a stranger, "do I like them?" is a useful proxy summary of dozens of micro-evaluations your brain has run. The problem is the same as for every shortcut in Influence: an operator who knows the inputs can stage them. The Tupperware home-party — Cialdini's "perfect compliance setting" — wraps reciprocation, liking, and unity into a single evening; the customer buys not from the company but from a friend, and sales resistance never gets a chance to engage.
The defense is structural rather than emotional. You cannot un-like someone in real time. But you can ask: did I like them faster, warmer, or more strongly than the situation justifies? Unusually fast warmth is the diagnostic. Once you've noticed, visualize the same offer from a stranger you don't like — if your answer changes, the liking is doing more work than the offer is.