The "watchmaker analogy" is a philosophical argument used to illustrate the existence of a designer or creator. It compares the complexity of a watch, which requires a watchmaker to assemble and function, to the complexity of the universe. Just as a watch's intricate parts work together for a purpose, the universe's intricate systems suggest a purposeful design. This analogy is often associated with the works of William Paley, who argued that the natural world exhibits signs of design similar to a watch. Critics of the analogy, including proponents of evolutionary biology, argue that natural processes can explain complexity without invoking a designer.