What is Tesler's law in UX design?
Tesler's law, also known as the law of conservation of complexity, was formulated by computer scientist Larry Tesler and states that every application has an inherent amount of complexity that cannot be reduced beyond a certain point. It can only be moved: either the system absorbs the complexity on behalf of the user, or the complexity is pushed onto the user to deal with. The designer's job is to decide where the complexity should live.
Why does Tesler's law matter for UX design?
Tesler's law clarifies that simplification has limits. You cannot make filing taxes as simple as ordering coffee because the task itself is genuinely complex. What you can do is absorb as much of that complexity as possible into the system, handling edge cases automatically, pre-filling information the system already knows, and providing intelligent defaults, so that users only encounter the irreducible complexity that genuinely requires their judgment.
What are examples of Tesler's law in interface design?
A calendar application that automatically detects time zones and converts meeting times for participants in different locations is absorbing complexity that would otherwise fall on the user. An e-commerce checkout that pre-fills the delivery address from the user's account is absorbing the complexity of address entry. An email client that suggests unsubscribing from newsletters based on reading patterns is absorbing the complexity of inbox management. Each of these reduces the cognitive load on users by handling complexity that the system is better positioned to manage.
What is the tension between simplicity and Tesler's law?
Overly aggressive simplification can violate Tesler's law in the other direction by hiding complexity users actually need access to. Removing advanced options to create a cleaner interface forces power users to work around the product or abandon it. The goal is not maximum simplicity but appropriate simplicity: absorbing complexity the system can handle better than users while preserving access to the complexity that requires human judgment and control.