“I know he made you a promise, but circumstances have changed.”
— Linda Vasquez, House of Cards, “Chapter 1” (2013)
As of December 31st, 2025, eCommerce giant Shopify employs 7600 individuals and serves millions of merchants across 175 different countries (Shopify Inc., 2026). How is it possible for so many people to work together toward a common goal? In a world that often feels so automatic, it is easy to take questions like this for granted. But for evolutionary biologists, such large-scale feats of human cooperation are nothing short of baffling. Many debates have been had around this topic, and scientists are still unable to agree on a definitive answer, but according to one theory, the key could lie in reciprocity (Trivers, 1971).
At every level, Shopify and other businesses like it are built on contractual obligations. Employees are onboarded with employment contracts that fix their pay, duties, and conditions of departure; merchants and customers accept terms of service that govern what each side owes the other; lawyers, landlords, and consultants are engaged through contracts specifying the work to be done and the price to be paid for their services. In every case, these contracts enforce a system of reciprocity which benefits all parties involved. In the words of The Royal Swedish Academy of Sciences (2016), that is what “[m]odern economies are held together by”.
But can all contracts be expressed in words and written down on paper, or are there also implicit contracts we sign into subconsciously, and perhaps even unknowingly? Psychologist Denise Rousseau explores this idea through a theory of “psychological contracts”.
Psychological contracts are the unwritten, unspoken agreements that govern how we interact with others. They are things we feel we owe, and the things we feel are owed in return (Rousseau, 1989). In a workplace, a formal contract can set a number of hours an employee is expected to work, and the salary that an employee is paid; but only a psychological contract can govern whether that employee uses those hours to the best of her ability, or whether her boss ever seriously considers her for a merit-based promotion. Psychological contracts are, at their core, subjective and experiential. No court room can judge whether or not one has been broken. And yet, breaching one can have very real consequences for the systems of reciprocity that hold organisations together. Breaches erode trust, and without trust people stop collaborating, stop taking initiative and stop sharing what they know. Stress rises, loyalty drops and outcomes suffer (Griep, 2025).
Psychological contracts are not always easy to navigate. By their very nature, their terms are never made explicit, and they are shaped by cultural upbringing, previous experience, and the cues and signals each side believes it has sent and received (Griep, 2025).
Suppose a contractor tries to strengthen a relationship with a loyal client by offering a temporary discount. The client may initially appreciate the gesture, but what happens if previous contractors have offered that client discounts that were understood to be permanent? Even though the current contractor never promised this, the client may expect it all the same. And now, when the contractor asks the client to return to paying the full rate, the client may feel that an implicit understanding has been broken. Neither party is necessarily being unreasonable or acting in bad faith. The contractor understood the discount as temporary; the client understood it as part of an ongoing relationship. Each entered into the agreement with a slightly different version of the psychological contract, and that mismatch in expectations created a breach.
So how can we ensure that we are not breaching the psychological contracts others are expecting us to follow, and that other parties truly understand the psychological contracts that we expect of them?
References
Griep, Y. (2025). Breaking promises, breaking trust: How psychological contract breach relates to trust trajectories and performance. European Management Journal. Advance online publication. https://doi.org/10.1016/j.emj.2025.10.007
Rousseau, D. M. (1989). Psychological and implied contracts in organizations. Employee Responsibilities and Rights Journal, 2(2), 121–139. https://doi.org/10.1007/BF01384942
The Royal Swedish Academy of Sciences. (2016, October 10). The prize in economic sciences 2016 [Press release]. NobelPrize.org. https://www.nobelprize.org/prizes/economic-sciences/2016/press-release/
Shopify Inc. (2026). Form 10-K: Annual report for the fiscal year ended December 31, 2025. U.S. Securities and Exchange Commission. https://www.sec.gov/Archives/edgar/data/1594805/000159480526000007/shop-20251231.htm
Trivers, R. L. (1971). The evolution of reciprocal altruism. The Quarterly Review of Biology, 46(1), 35–57. https://doi.org/10.1086/406755
Willimon, B. (Writer), & Fincher, D. (Director). (2013, February 1). Chapter 1 (Season 1, Episode 1) [TV series episode]. In D. Fincher, B. Willimon, J. Donen, E. Roth, K. Spacey, D. Brunetti, A. Davies, M. Dobbs, & J. Melfi (Executive Producers), House of cards. Donen/Fincher/Roth; Trigger Street Productions; Media Rights Capital.