Tesler's Law¶

Status: emerging
Last updated: 2026-06-02
Sources: Lawsofux.Pdf
Tags: [ux-design, design-principles, heuristics, teslers-law, conservation-of-complexity, simplicity, interaction-design]

Summary¶

Tesler's law, the law of conservation of complexity, states that every system carries a certain amount of complexity that cannot be removed — it can only be shifted (Yablonski, 2024). Applied to UX, the question is who absorbs that irreducible complexity: the design should take it on so the user does not have to. Yablonski attributes the principle to Larry Tesler and argues that good design hides inherent complexity behind a simple interface rather than pretending it away.

Body¶

Context¶

Yablonski (2024), in the Tesler's Law chapter of Laws of UX, applies the conservation-of-complexity principle to the division of effort between system and user. The chapter states the law, gives its origin in Larry Tesler's work, and derives guidance for absorbing complexity in design. Within this knowledge base the article connects to Usability And User Experience (simplicity and user-centred design), the choice-reduction law Hicks Law, and the system-design framing of Human Systems Integration; it is one of the complexity laws in Laws Of Ux.

Key Points¶

Yablonski states the law as: for any system there is a certain amount of complexity that cannot be reduced (PDF pp. 127–138, orig. pp. 107–118). He attributes it to Larry Tesler, who worked at Xerox PARC and later Apple, and illustrates the idea with Tesler's own creation of a generic application that absorbed configuration complexity so that developers — and ultimately users — faced less of it.

The design implication is that complexity is conserved, not eliminated, so the designer must decide where it lives. Well-designed products take on the inherent complexity of a task internally and present the user with a simple surface, rather than exposing the full complexity or forcing the user to manage it (PDF pp. 127–138, orig. pp. 107–118). The chapter cautions against oversimplification that merely pushes complexity back onto the user in disguised form.

Conclusion¶

Yablonski (2024) concludes that since a task's essential complexity cannot be wished away, the designer's job is to absorb it on the user's behalf — moving difficulty from the interface to the implementation. Simplicity for the user is achieved by the system shouldering complexity, not by denying it exists.

References¶

Yablonski, J. (2024) Laws of UX: Using Psychology to Design Better Products & Services. 2nd edn. Sebastopol, CA: O'Reilly Media. yablonski2024lawsux

Open Questions¶

How should designers decide which parts of a task's irreducible complexity to absorb and which to expose to expert users who may want control?
Where does absorbing complexity tip into harmful oversimplification that merely hides difficulty rather than resolving it?