The science of persuasion

Cialdini is a well-known professor who writes popular books about marketing and persuasion. His theory of influence has six principles, which are discussed in this 2001 article.

Cialdini, R. (2001) ‘Harnessing the science of persuasion’, Harvard Business Review, vol. 79, no. 9, pp. 72-79 [Online]. Available at


  1. The principle of liking
  2. The principle of reciprocity
  3. The principle of social proof
  4. The principle of consistency
  5. The principle of authority
  6. The principle of scarcity
  7. Putting it all together


Liking: People like those who like them.

To increase liking, use similarity and praise. Find similarities with informal conversations. Be sure to establish bonds early, not just when you need someone’s support. Praise increases liking even when it is not warranted, and so it can even help difficult relationships.

Reciprocity: People repay in kind.

An obvious example is gifts (such as the gifts sales representatives give to customers, or even gifts a manager may give to their staff). Less obvious is modelling the behavior you want to receive from others, such as trust, cooperation, or helpfulness.

Social proof: People follow the lead of similar others.

If people see testimonials or other evidence of support from people like them or from people in circumstances similar to their own, they will take this as a cue for how they should behave.

Consistency: People align with their commitments.

If people publicly go on the record with a commitment, they are likely to follow through with it. They will feel obligated to do so, especially if the commitment was made actively (that is, said out loud or written down), publicly, and voluntarily.

Authority: People defer to experts.

Establish your expertise by sharing an anecdote or story about an experience that is central to the area of expertise.

Scarcity:  People want more of what they can have less of.

If something is less available — such as goods, information, time, or data — it is more desirable or valuable. This is why “loss language” works (framing an offer in terms of what you will lose if you don’t act, instead of in terms of what you will gain).

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