The Four Causes and Purpose in Nature

Aristotle argued that to understand anything fully, we must answer four kinds of 'why' questions, which he called causes. Take a bronze statue: its material cause is the bronze; its formal cause is the shape or design; its efficient cause is the sculptor who made it; and its final cause is its purpose, perhaps to honor a god. Aristotle believed natural things have final causes too: an eye exists for seeing, and an acorn develops for the sake of becoming an oak.

This view, called teleology, sees purpose built into nature, summed up in his saying that nature does nothing in vain. Teleology was powerful in biology, where organs clearly serve functions. However, early modern scientists such as Francis Bacon argued that searching for purposes in physics hindered progress, and Darwin later explained apparent design through natural selection. Debate continues over how purpose-language fits in science.