STAKEHOLDERS & COMMS · LESSON 05.02intermediate

Influence without authority.

The PM's defining skill — getting things done when you can't fire anyone.

↳ tl;dr

You don't manage the engineers building your project, the designers shaping it, or the legal team reviewing it. You still need them to deliver on time. Cialdini's six principles — reciprocity, commitment, social proof, authority, liking, scarcity — are the durable toolkit (he later added unity).

Cialdini's six (plus one)

  • Reciprocity — people return favors. Help others before you need help yourself.
  • Commitment / Consistency — people honor public commitments. Get a small public yes; the bigger ask follows.
  • Social proof — people follow what similar others are doing. "Three of your peer teams have signed off" works.
  • Authority — people defer to credible expertise. Citing the right source matters.
  • Liking — people say yes to those they like. Spend time on relationships before you need them.
  • Scarcity — people want what's limited. "The window for this decision closes Friday" (when true).
  • Unity (added 2016) — shared identity. "We engineers" is more powerful than "you engineers."

the manipulation problem

Cialdini explicitly warns against using these principles dishonestly — fake scarcity, manufactured social proof, or phony authority. Used dishonestly they work once, then the relationship is over. Used honestly they're how trust builds over years.

The PM's daily moves

  • Reciprocity — when an eng team unblocks you, surface it publicly to their manager. Banking goodwill.
  • Commitment — "Can we agree the goal is X?" Once they agree, the next ask is consistent with that agreement.
  • Social proof — "Teams A and B already adopted this approach; here's what they learned."
  • Liking — care about the people. Remember names, ask follow-up questions, show up to their demos.

// sources

Sources cited

  1. [01]
    Influence: The Psychology of Persuasion

    Cialdini, R. · HarperBusiness · 1984 · retrieved 2026-05

    Six principles: reciprocity, commitment, social proof, authority, liking, scarcity (later: unity).

// sources

Further reading

  1. [01]
    Influence: The Psychology of Persuasion

    Cialdini, R. · HarperBusiness · 1984 · retrieved 2026-05

    Six principles: reciprocity, commitment, social proof, authority, liking, scarcity (later: unity).