Tony Hoare’s observation, from his 1980 Turing Award lecture, contrasts two approaches to software design. The first makes a system so simple that any flaws are immediately visible. The second makes it so complicated that flaws can hide undetected. Hoare notes that the first approach is far harder to achieve, because reducing a design to its essentials demands discipline, clear thinking, and a willingness to accept constraints. Complexity, by contrast, often accumulates without resistance and can give a false impression of completeness while masking errors. The remark is widely cited in software engineering as an argument for simplicity over unnecessary elaboration. Although Hoare was describing programming, the principle is often applied more broadly to engineering, management, and design, where intricate solutions may appear thorough yet conceal weaknesses. The quotation reflects a recurring theme in Hoare’s work: that reliability depends on keeping designs comprehensible.

Full quotation

“The most important property of a program is whether it accomplishes the intentions of its user. If these intentions can be described rigorously by making assertions about the values of variables at the end (or at intermediate points) of the execution of the program, then the techniques described in this paper may be used to prove the correctness of the program, provided that the implementation of the programming language conforms to the axioms and rules which have been used in the proof.”