teleology: Causality in which the effect is explained by the end (Greek telos) to be realized. Teleology thus differs essentially from efficient causality, in which an effect is dependent on prior events. Aristotle’s account of teleology declared that a full explanation of anything must consider it’s the final cause—the purpose for which the thing exists or was produced. Following Aristotle, many philosophers have conceived of biological processes as involving the operation of a guiding end. Modern science has tended to appeal only to efficient causes in its investigations. See also mechanism.
Excerpted from: Stevens, Mark A., Ed. Merriam-Webster’s Collegiate Encyclopedia. Springfield, Massachusetts: Merriam-Webster, 2000.